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Question 1
Correct
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A 70-year-old man visits his primary care physician with complaints of hearing difficulties. He states that he has been increasingly struggling to hear his wife's conversations for the past six months. He is concerned that this problem will worsen and eventually lead to complete hearing loss, making it difficult for him to communicate with his children over the phone. His wife is also distressed by the situation, as he frequently asks her to turn up the volume on the television. The man has no history of exposure to loud noises and has well-controlled hypertension. He is a retired police officer and currently resides with his wife. What is the primary pathology underlying this man's most likely diagnosis?
Your Answer: Degeneration of the cells at the cochlear base
Explanation:The patient has a gradual-onset hearing loss, which is most likely due to presbycusis, an aging-related sensorineural hearing loss. This condition has multiple causes, including environmental factors like noise pollution and biological factors like genetics and oxidative stress. Damage to the organ of Corti stereocilia from exposure to sudden loud noises can also cause hearing loss, which is typically sudden and associated with a history of exposure to loud noises. Other conditions that can cause hearing loss include cholesteatoma, which is due to the accumulation of keratin debris in the middle ear, and otosclerosis, which is characterized by the overgrowth of bone in the middle ear.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 2
Incorrect
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A woman in her 30s is stabbed in the chest to the right of the manubriosternal angle. Which structure is least likely to be injured in this scenario?
Your Answer: Right phrenic nerve
Correct Answer: Right recurrent laryngeal nerve
Explanation:The right vagus nerve gives rise to the right recurrent laryngeal nerve at a more proximal location, which then curves around the subclavian artery in a posterior direction. Therefore, out of the given structures, it is the least susceptible to injury.
The mediastinum is the area located between the two pulmonary cavities and is covered by the mediastinal pleura. It extends from the thoracic inlet at the top to the diaphragm at the bottom. The mediastinum is divided into four regions: the superior mediastinum, middle mediastinum, posterior mediastinum, and anterior mediastinum.
The superior mediastinum is the area between the manubriosternal angle and T4/5. It contains important structures such as the superior vena cava, brachiocephalic veins, arch of aorta, thoracic duct, trachea, oesophagus, thymus, vagus nerve, left recurrent laryngeal nerve, and phrenic nerve. The anterior mediastinum contains thymic remnants, lymph nodes, and fat. The middle mediastinum contains the pericardium, heart, aortic root, arch of azygos vein, and main bronchi. The posterior mediastinum contains the oesophagus, thoracic aorta, azygos vein, thoracic duct, vagus nerve, sympathetic nerve trunks, and splanchnic nerves.
In summary, the mediastinum is a crucial area in the thorax that contains many important structures and is divided into four regions. Each region contains different structures that are essential for the proper functioning of the body.
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This question is part of the following fields:
- Respiratory System
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Question 3
Incorrect
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A 55-year-old man visits his GP complaining of shortness of breath, haemoptysis, and unintentional weight loss over the past 3 months. The GP refers him to the respiratory clinic for suspected lung cancer, and further investigations reveal a stage 2 squamous cell carcinoma of the lung. What is the most frequently associated paraneoplastic phenomenon with this type of cancer?
Your Answer: Syndrome of inappropriate ADH secretion (SIADH)
Correct Answer: Parathyroid hormone-related protein (PTHrP)
Explanation:The correct answer is PTHrP, which is a paraneoplastic syndrome often associated with squamous cell lung cancer. PTHrP is a protein that functions similarly to parathyroid hormone and can cause hypercalcaemia when secreted by cancer cells.
Acanthosis nigricans is another paraneoplastic phenomenon that is commonly associated with gastric adenocarcinoma. This condition causes hyperpigmentation of skin folds, such as the armpits.
The syndrome of inappropriate ADH secretion is often linked to small cell lung cancer. This condition involves the hypersecretion of ADH, which leads to dilutional hyponatraemia and its associated symptoms.
Carcinoid syndrome is a paraneoplastic syndrome that is typically associated with neuroendocrine tumours that have metastasised to the liver. This condition causes hypersecretion of serotonin and other substances, resulting in facial flushing, palpitations, and gastrointestinal upset.
Lung cancer can present with paraneoplastic features, which are symptoms caused by the cancer but not directly related to the tumor itself. Small cell lung cancer can cause the secretion of ADH and, less commonly, ACTH, which can lead to hypertension, hyperglycemia, hypokalemia, alkalosis, and muscle weakness. Lambert-Eaton syndrome is also associated with small cell lung cancer. Squamous cell lung cancer can cause the secretion of parathyroid hormone-related protein, leading to hypercalcemia, as well as clubbing and hypertrophic pulmonary osteoarthropathy. Adenocarcinoma can cause gynecomastia and hypertrophic pulmonary osteoarthropathy. Hypertrophic pulmonary osteoarthropathy is a painful condition involving the proliferation of periosteum in the long bones. Although traditionally associated with squamous cell carcinoma, some studies suggest that adenocarcinoma is the most common cause.
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This question is part of the following fields:
- Respiratory System
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Question 4
Incorrect
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A 25-year-old man is receiving an endotracheal intubation. At which vertebral level does the trachea originate?
Your Answer: C4
Correct Answer: C6
Explanation:The trachea starts at the sixth cervical vertebrae and ends at the fifth thoracic vertebrae (or sixth in individuals with a tall stature during deep inhalation).
Anatomy of the Trachea
The trachea, also known as the windpipe, is a tube-like structure that extends from the C6 vertebrae to the upper border of the T5 vertebrae where it bifurcates into the left and right bronchi. It is supplied by the inferior thyroid arteries and the thyroid venous plexus, and innervated by branches of the vagus, sympathetic, and recurrent nerves.
In the neck, the trachea is anterior to the isthmus of the thyroid gland, inferior thyroid veins, and anastomosing branches between the anterior jugular veins. It is also surrounded by the sternothyroid, sternohyoid, and cervical fascia. Posteriorly, it is related to the esophagus, while laterally, it is in close proximity to the common carotid arteries, right and left lobes of the thyroid gland, inferior thyroid arteries, and recurrent laryngeal nerves.
In the thorax, the trachea is anterior to the manubrium, the remains of the thymus, the aortic arch, left common carotid arteries, and the deep cardiac plexus. Laterally, it is related to the pleura and right vagus on the right side, and the left recurrent nerve, aortic arch, and left common carotid and subclavian arteries on the left side.
Overall, understanding the anatomy of the trachea is important for various medical procedures and interventions, such as intubation and tracheostomy.
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This question is part of the following fields:
- Respiratory System
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Question 5
Incorrect
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A 60-year-old diabetic patient presents to the clinic with a chief complaint of hearing loss. After conducting a Webber’s and Rinne’s test, the following results were obtained:
- Webber’s test: lateralizes to the left ear
- Rinne’s test (left ear): bone conduction > air conduction
- Rinne’s test (right ear): air conduction > bone conduction
Based on these findings, what is the probable cause of the patient's hearing loss?Your Answer: Acoustic neuroma
Correct Answer: Otitis media with effusion
Explanation:The Weber test lateralises to the side with bone conduction > air conduction, indicating conductive hearing loss on that side. The options given include acoustic neuroma (sensorineural hearing loss), otitis media with effusion (conductive hearing loss), temporal lobe epilepsy (no conductive hearing loss), and Meniere’s disease (vertigo, tinnitus, and fluctuating hearing loss). The correct answer is otitis media with effusion.
Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness
Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.
Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.
The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.
Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 6
Correct
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Which one of the following muscles is supplied by the external laryngeal nerve?
Your Answer: Cricothyroid
Explanation:Anatomy of the Larynx
The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.
The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.
The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.
The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.
Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.
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This question is part of the following fields:
- Respiratory System
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Question 7
Correct
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A 68-year-old woman has been diagnosed with laryngeal cancer and has quit smoking. Surgery is planned to remove the cancer through a laryngectomy. What vertebral level/levels will the organ be located during the procedure?
Your Answer: C3 to C6
Explanation:The larynx is situated in the front of the neck at the level of the C3-C6 vertebrae. This is the correct location for accessing the larynx during a laryngectomy. The larynx is not located at the C1-C2 level, as these are the atlas bones. It is also not located at the C2-C3 level, which is where the hyoid bone can be found. The C7 level is where the isthmus of the thyroid gland is located, not the larynx.
Anatomy of the Larynx
The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.
The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.
The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.
The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.
Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.
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This question is part of the following fields:
- Respiratory System
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Question 8
Correct
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Which one of the following is associated with increased lung compliance in elderly individuals?
Your Answer: Emphysema
Explanation:Understanding Lung Compliance in Respiratory Physiology
Lung compliance refers to the extent of change in lung volume in response to a change in airway pressure. An increase in lung compliance can be caused by factors such as aging and emphysema, which is characterized by the loss of alveolar walls and associated elastic tissue. On the other hand, a decrease in lung compliance can be attributed to conditions such as pulmonary edema, pulmonary fibrosis, pneumonectomy, and kyphosis. These conditions can affect the elasticity of the lungs and make it more difficult for them to expand and contract properly. Understanding lung compliance is important in respiratory physiology as it can help diagnose and manage various respiratory conditions. Proper management of lung compliance can improve lung function and overall respiratory health.
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This question is part of the following fields:
- Respiratory System
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Question 9
Incorrect
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A 52-year-old woman visited her family physician with complaints of pain in her wrist and small joints of the hand. She mentioned that her joints felt stiff in the morning but improved throughout the day. The doctor prescribed glucocorticoids and methotrexate, which helped alleviate her symptoms. After a year, she returned to her doctor with a dry cough and shortness of breath that had been bothering her for a month. She denied any recent weight loss or coughing up blood. She is a non-smoker and drinks alcohol moderately. The woman has no significant medical or surgical history and has been a homemaker while her husband works in a shipyard. Her father died of a heart attack at the age of 77. What is the most likely finding on her chest X-ray?
Your Answer: Normal chest X-ray
Correct Answer: Intrapulmonary nodules
Explanation:1. Caplan syndrome is a condition characterized by intrapulmonary nodules found peripherally and bilaterally in individuals with both pneumoconiosis and rheumatoid arthritis. The immune system changes associated with rheumatoid arthritis are thought to affect the body’s response to coal dust particles, leading to the development of nodules.
2. A normal chest X-ray does not rule out the possibility of underlying respiratory disease. If there is a high clinical suspicion, further investigation should be pursued to confirm or rule out potential diagnoses, such as asthma.
3. Chronic obstructive respiratory disease, which includes chronic bronchitis and emphysema, is characterized by hyperinflated lungs and a flattened diaphragm on chest X-ray. This is due to the loss of elastic recoil in the lungs and airway obstruction caused by inflammation of the bronchi.
4. Silicosis is a restrictive lung disease that develops in individuals exposed to silica, such as sandblasters and those working in silica mines. Eggshell calcification of hilar lymph nodes is a characteristic finding on chest X-ray.
5. Squamous cell carcinoma of the lungs, a non-small cell type of lung cancer, is associated with a central bronchial opacity around the hilar region on chest X-ray. This type of cancer is more common in smokers and may be accompanied by hypercalcemia as a paraneoplastic syndrome.Respiratory Manifestations of Rheumatoid Arthritis
Patients with rheumatoid arthritis may experience a range of respiratory problems. These can include pulmonary fibrosis, pleural effusion, pulmonary nodules, bronchiolitis obliterans, and pleurisy. Additionally, drug therapy for rheumatoid arthritis, such as methotrexate, can lead to complications like pneumonitis. In some cases, patients may develop Caplan’s syndrome, which involves the formation of massive fibrotic nodules due to occupational coal dust exposure. Finally, immunosuppression caused by rheumatoid arthritis treatment can increase the risk of infection, including atypical infections. Overall, it is important for healthcare providers to be aware of these potential respiratory complications in patients with rheumatoid arthritis.
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This question is part of the following fields:
- Respiratory System
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Question 10
Incorrect
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A father brings his 9-year-old daughter to your general practice, as he is worried about her hearing. He notices that he has to repeat himself when talking to her, and thinks she is often 'in her own little world'. During the examination, the Rinne test is positive on the left and negative on the right. What conclusions can be drawn from this?
Your Answer: Conductive hearing loss on the left.
Correct Answer: Can not tell if both sides are affected.
Explanation:The Rinne and Weber tests are used to diagnose hearing loss. The Rinne test involves comparing air and bone conduction, with a positive result indicating a healthy or sensorineural loss and a negative result indicating a conductive loss. The Weber test involves placing a tuning fork on the forehead and determining if the sound is symmetrical or louder on one side, with a conductive loss resulting in louder sound on the affected side and a sensorineural loss resulting in louder sound on the non-affected side. When used together, these tests can provide more information about the type and affected side of hearing loss.
Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness
Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.
Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.
The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.
Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 11
Incorrect
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An 83-year-old man is on the stroke ward after suffering a total anterior circulation stroke of the left hemisphere. He is receiving assistance from the physiotherapists to mobilize, but the speech and language team has determined that he has an unsafe swallow. On the 6th day of his hospital stay, he begins to feel unwell.
Upon examination, his temperature is 38.4ºC, heart rate of 112/min, respiratory rate of 18, and his blood pressure is 100/76 mmHg. Aspiration pneumonia is suspected. Which area of the body is most likely affected?Your Answer: Left lower lobe
Correct Answer: Right middle lobe
Explanation:Aspiration pneumonia is a common occurrence in stroke patients during the recovery phase, with a higher likelihood of affecting the right lung due to the steeper course of the right bronchus. This type of pneumonia is often caused by unsafe swallowing and can lead to prolonged hospital stays and increased mortality rates. The right middle and lower lobes are the most susceptible to aspirated gastric contents, while the right upper lobe is less likely due to gravity. It’s important to consider aspiration pneumonia as a differential diagnosis when assessing stroke patients, especially those with severe pathology.
Aspiration pneumonia is a type of pneumonia that occurs when foreign substances, such as food or saliva, enter the bronchial tree. This can lead to inflammation and a chemical pneumonitis, as well as the introduction of bacterial pathogens. The condition is often caused by an impaired swallowing mechanism, which can be a result of neurological disease or injury, intoxication, or medical procedures such as intubation. Risk factors for aspiration pneumonia include poor dental hygiene, swallowing difficulties, prolonged hospitalization or surgery, impaired consciousness, and impaired mucociliary clearance. The right middle and lower lung lobes are typically the most affected areas. The bacteria involved in aspiration pneumonia can be aerobic or anaerobic, with examples including Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, Klebsiella, Bacteroides, Prevotella, Fusobacterium, and Peptostreptococcus.
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This question is part of the following fields:
- Respiratory System
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Question 12
Incorrect
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An 80-year-old man is brought to the emergency department in respiratory arrest. According to his partner, he has a history of congestive heart failure and has recently been battling an infection. After being placed on mechanical ventilation, you observe that the patient has decreased lung compliance.
What could be the cause of this observation?Your Answer: Loss of lung connective tissue with age
Correct Answer: Pulmonary oedema
Explanation:Reduced lung compliance is a common consequence of pulmonary edema, which occurs when fluid accumulates in the alveoli and exerts mechanical stress on the air-filled alveoli. This can happen in patients with acute decompensation of congestive cardiac failure, often triggered by an infection. On the other hand, emphysema can increase compliance due to long-term damage that reduces the elastic recoil of the lungs. Additionally, lung surfactant produced by type II pneumocytes can increase lung compliance. Finally, aging can also lead to increased compliance as the loss of lung connective tissue can reduce elastic recoil.
Understanding Lung Compliance in Respiratory Physiology
Lung compliance refers to the extent of change in lung volume in response to a change in airway pressure. An increase in lung compliance can be caused by factors such as aging and emphysema, which is characterized by the loss of alveolar walls and associated elastic tissue. On the other hand, a decrease in lung compliance can be attributed to conditions such as pulmonary edema, pulmonary fibrosis, pneumonectomy, and kyphosis. These conditions can affect the elasticity of the lungs and make it more difficult for them to expand and contract properly. Understanding lung compliance is important in respiratory physiology as it can help diagnose and manage various respiratory conditions. Proper management of lung compliance can improve lung function and overall respiratory health.
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This question is part of the following fields:
- Respiratory System
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Question 13
Correct
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A 60-year-old male patient complains of chronic productive cough and difficulty breathing. He has been smoking 10 cigarettes per day for the past 30 years. What is the number of pack years equivalent to his smoking history?
Your Answer: 15
Explanation:Pack Year Calculation
Pack year calculation is a tool used to estimate the risk of tobacco exposure. It is calculated by multiplying the number of packs of cigarettes smoked per day by the number of years of smoking. One pack of cigarettes contains 20 cigarettes. For instance, if a person smoked half a pack of cigarettes per day for 30 years, their pack year history would be 15 (1/2 x 30 = 15).
The pack year calculation is a standardized method of measuring tobacco exposure. It helps healthcare professionals to estimate the risk of developing smoking-related diseases such as lung cancer, chronic obstructive pulmonary disease (COPD), and heart disease. The higher the pack year history, the greater the risk of developing these diseases. Therefore, it is important for individuals who smoke or have a history of smoking to discuss their pack year history with their healthcare provider to determine appropriate screening and prevention measures.
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This question is part of the following fields:
- Respiratory System
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Question 14
Incorrect
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Which one of the following is not found in the anterior mediastinum?
Your Answer: Main bronchi
Correct Answer: Thoracic duct
Explanation:The posterior and superior mediastinum contain the thoracic duct.
The mediastinum is the area located between the two pulmonary cavities and is covered by the mediastinal pleura. It extends from the thoracic inlet at the top to the diaphragm at the bottom. The mediastinum is divided into four regions: the superior mediastinum, middle mediastinum, posterior mediastinum, and anterior mediastinum.
The superior mediastinum is the area between the manubriosternal angle and T4/5. It contains important structures such as the superior vena cava, brachiocephalic veins, arch of aorta, thoracic duct, trachea, oesophagus, thymus, vagus nerve, left recurrent laryngeal nerve, and phrenic nerve. The anterior mediastinum contains thymic remnants, lymph nodes, and fat. The middle mediastinum contains the pericardium, heart, aortic root, arch of azygos vein, and main bronchi. The posterior mediastinum contains the oesophagus, thoracic aorta, azygos vein, thoracic duct, vagus nerve, sympathetic nerve trunks, and splanchnic nerves.
In summary, the mediastinum is a crucial area in the thorax that contains many important structures and is divided into four regions. Each region contains different structures that are essential for the proper functioning of the body.
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This question is part of the following fields:
- Respiratory System
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Question 15
Incorrect
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Which of the following laryngeal tumors is unlikely to spread to the cervical lymph nodes?
Your Answer: Supraglottic
Correct Answer: Glottic
Explanation:The area of the vocal cords lacks lymphatic drainage, making it a lymphatic boundary. The upper portion above the vocal cords drains to the deep cervical nodes through vessels that penetrate the thyrohyoid membrane. The lower portion below the vocal cords drains to the pre-laryngeal, pre-tracheal, and inferior deep cervical nodes. The aryepiglottic and vestibular folds have a significant lymphatic drainage and are prone to early metastasis.
Anatomy of the Larynx
The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.
The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.
The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.
The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.
Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.
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This question is part of the following fields:
- Respiratory System
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Question 16
Correct
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A 78-year-old man comes to the emergency department complaining of increasing difficulty in breathing over the past two days. He has a medical history of squamous cell lung cancer.
Upon examination, the trachea is observed to have shifted towards the left side, with dull percussion and absence of breath sounds throughout the left chest.
What is the probable diagnosis?Your Answer: Left lung collapse
Explanation:When a lung collapses, it can cause the trachea to shift towards the affected side, and there may be dullness on percussion and reduced breath sounds throughout the lung field. This is because the decrease in pressure on the affected side causes the mediastinum and trachea to move towards it.
A massive pleural effusion, on the other hand, would cause widespread dullness and absent breath sounds, but it would push the trachea away from the affected side due to increased pressure.
Pneumonia typically only affects one lung zone, so there would not be widespread dullness or absent breath sounds throughout the hemithorax. It also does not usually affect the position of the mediastinum or trachea.
Pneumothorax would be hyperresonant on percussion, not dull, and it may push the trachea away from the affected side in severe cases, but this is more common in tension pneumothoraces that occur after trauma.
A lobectomy may cause the trachea to shift towards the same side as the surgery due to decreased pressure, but it would not cause dullness or absent breath sounds throughout the lung fields.
Understanding White Lung Lesions on Chest X-Rays
When examining a chest x-ray, white shadowing in the lungs can indicate a variety of conditions. These may include consolidation, pleural effusion, collapse, pneumonectomy, specific lesions such as tumors, or fluid accumulation such as pulmonary edema. In cases where there is a complete white-out of one side of the chest, it is important to assess the position of the trachea. If the trachea is pulled towards the side of the white-out, it may indicate pneumonectomy, lung collapse, or pulmonary hypoplasia. If the trachea is pushed away from the white-out, it may indicate pleural effusion, a large thoracic mass, or a diaphragmatic hernia. Other signs of a positive mass effect may include leftward bowing of the azygo-oesophageal recess and splaying of the ribs on the affected side. Understanding the potential causes of white lung lesions on chest x-rays can aid in accurate diagnosis and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 17
Incorrect
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Which of the following organisms is not a common cause of respiratory tract infections in elderly patients, with cystic fibrosis?
Your Answer: Aspergillus
Correct Answer: Strongyloides stercoralis
Explanation:Understanding Cystic Fibrosis
Cystic fibrosis is a genetic disorder that causes thickened secretions in the lungs and pancreas. It is an autosomal recessive condition that occurs due to a defect in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which regulates a chloride channel. In the UK, 80% of CF cases are caused by delta F508 on chromosome 7, and the carrier rate is approximately 1 in 25.
CF patients are at risk of colonization by certain organisms, including Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia (previously known as Pseudomonas cepacia), and Aspergillus. These organisms can cause infections and exacerbate symptoms in CF patients. It is important for healthcare providers to monitor and manage these infections to prevent further complications.
Overall, understanding cystic fibrosis and its associated risks can help healthcare providers provide better care for patients with this condition.
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This question is part of the following fields:
- Respiratory System
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Question 18
Incorrect
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A 7-year-old boy is brought to the clinic by his father, who is worried about his son's hearing. The father has noticed that his son frequently asks him to repeat himself and tends to turn up the volume on the TV. During Weber's test, the patient indicates that the sound is louder on the right side. What conclusion can be drawn from this finding?
Your Answer: Sensorineural hearing loss of left ear.
Correct Answer: Can not tell which side is affected.
Explanation:The Weber test alone cannot determine which side of the patient’s hearing is affected. The test involves placing a tuning fork on the forehead and asking the patient to report if the sound is symmetrical or louder on one side. If the sound is louder on the left side, it could indicate a conductive hearing loss on the left or a sensorineural hearing loss on the right. To obtain more information, the Weber test should be performed in conjunction with the Rinne test, which involves comparing air conduction and bone conduction.
Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness
Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.
Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.
The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.
Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 19
Incorrect
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A 6-month-old infant is brought to the paediatrician due to increased work of breathing. The infant was born at term and via spontaneous vaginal delivery 6 months ago.
During the examination, the paediatrician observes moderate subcostal and intercostal recession and notes that the infant appears tachypnoeic. The infant's temperature is 38.9ºC, and a chest x-ray is ordered, which reveals some consolidation in the right lower zone. Broad-spectrum antibiotics are initiated.
Upon reviewing the infant's oxygen dissociation curve, the paediatrician notes a leftward shift relative to the standard adult curve. What is the cause of this appearance in the infant's oxygen dissociation curve?Your Answer: Hyperthermia
Correct Answer: Foetal haemoglobin (HbF)
Explanation:The factor that shifts the oxygen dissociation curve to the left is foetal haemoglobin (HbF). This is because HbF has a higher affinity for oxygen than adult haemoglobin, haemoglobin A, which allows maternal haemoglobin to preferentially offload oxygen to the foetus across the placenta.
Understanding the Oxygen Dissociation Curve
The oxygen dissociation curve is a graphical representation of the relationship between the percentage of saturated haemoglobin and the partial pressure of oxygen in the blood. It is not influenced by the concentration of haemoglobin. The curve can shift to the left or right, indicating changes in oxygen delivery to tissues. When the curve shifts to the left, there is increased saturation of haemoglobin with oxygen, resulting in decreased oxygen delivery to tissues. Conversely, when the curve shifts to the right, there is reduced saturation of haemoglobin with oxygen, leading to enhanced oxygen delivery to tissues.
The L rule is a helpful mnemonic to remember the factors that cause a shift to the left, resulting in lower oxygen delivery. These factors include low levels of hydrogen ions (alkali), low partial pressure of carbon dioxide, low levels of 2,3-diphosphoglycerate, and low temperature. On the other hand, the mnemonic ‘CADET, face Right!’ can be used to remember the factors that cause a shift to the right, leading to raised oxygen delivery. These factors include carbon dioxide, acid, 2,3-diphosphoglycerate, exercise, and temperature.
Understanding the oxygen dissociation curve is crucial in assessing the oxygen-carrying capacity of the blood and the delivery of oxygen to tissues. By knowing the factors that can shift the curve to the left or right, healthcare professionals can make informed decisions in managing patients with respiratory and cardiovascular diseases.
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This question is part of the following fields:
- Respiratory System
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Question 20
Incorrect
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A 50-year-old man suffers a closed head injury and experiences a decline in consciousness upon arrival at the hospital. To monitor his intracranial pressure, an ICP monitor is inserted. What is the normal range for intracranial pressure?
Your Answer: 25 - 30 mm Hg
Correct Answer: 7 - 15mm Hg
Explanation:The typical range for intracranial pressure is 7 to 15 mm Hg, with the brain able to tolerate increases up to 24 mm Hg before displaying noticeable clinical symptoms.
Understanding the Monro-Kelly Doctrine and Autoregulation in the CNS
The Monro-Kelly doctrine governs the pressure within the cranium by considering the skull as a closed box. The loss of cerebrospinal fluid (CSF) can accommodate increases in mass until a critical point is reached, usually at 100-120ml of CSF lost. Beyond this point, intracranial pressure (ICP) rises sharply, and pressure will eventually equate with mean arterial pressure (MAP), leading to neuronal death and herniation.
The central nervous system (CNS) has the ability to autoregulate its own blood supply through vasoconstriction and dilation of cerebral blood vessels. However, extreme blood pressure levels can exceed this capacity, increasing the risk of stroke. Additionally, metabolic factors such as hypercapnia can cause vasodilation, which is crucial in ventilating head-injured patients.
It is important to note that the brain can only metabolize glucose, and a decrease in glucose levels can lead to impaired consciousness. Understanding the Monro-Kelly doctrine and autoregulation in the CNS is crucial in managing intracranial pressure and preventing neurological damage.
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This question is part of the following fields:
- Respiratory System
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Question 21
Incorrect
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A 27-year-old male admitted to the ICU after a car accident has a pneumothorax. Using a bedside spirometer, his inspiratory and expiratory volumes were measured. What is the typical tidal volume for a male of his age?
Your Answer: 400ml
Correct Answer: 500ml
Explanation:The amount of air that is normally breathed in and out without any extra effort is called tidal volume, which is 500ml in males and 350ml in females.
Understanding Lung Volumes in Respiratory Physiology
In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.
Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.
Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.
Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.
Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.
Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.
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This question is part of the following fields:
- Respiratory System
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Question 22
Correct
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A 26-year-old man has been referred to ENT by his doctor as he has swallowed a small chicken bone that feels stuck in his throat. During laryngoscopy, a chicken bone is observed lodged in the piriform recess. Which of the following nerves is most likely to be affected by the chicken bone?
Your Answer: Internal laryngeal nerve
Explanation:When foreign objects get stuck in the piriform recess, particularly sharp items like bones from fish or chicken, they can harm the internal laryngeal nerve that lies beneath the mucous membrane in that area. Retrieving these objects also poses a risk of damaging the internal laryngeal nerve. However, the other nerves are not likely to be impacted.
Anatomy of the Larynx
The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.
The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.
The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.
The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.
Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.
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This question is part of the following fields:
- Respiratory System
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Question 23
Incorrect
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A 40-year-old woman visits her GP after being treated at the Emergency Department for a foreign body lodged in her throat for 2 days. Although the object has been removed, she is experiencing difficulty swallowing. Upon further questioning, she mentions altered sensation while swallowing, describing it as a sensation of 'not feeling like food is being swallowed' during meals.
Which nerve or nerves are likely to have been affected?Your Answer: External laryngeal nerve
Correct Answer: Internal laryngeal nerve
Explanation:The internal laryngeal nerve is responsible for providing sensory information to the supraglottis and branches off from the superior laryngeal nerve. It is important to note that the cervical plexus, external laryngeal nerve, recurrent laryngeal nerve, and superior laryngeal nerve do not perform the same function as the internal laryngeal nerve.
Anatomy of the Larynx
The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.
The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.
The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.
The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.
Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.
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This question is part of the following fields:
- Respiratory System
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Question 24
Correct
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A 25-year-old male patient complains of sore throat, malaise, and fatigue for the past 5 days. During the examination, a significant peritonsillar abscess is observed. What is the probable causative organism responsible for this infection?
Your Answer: Streptococcus pyogenes
Explanation:Streptococcal organisms are the most frequent cause of bacterial tonsillitis, which can lead to quinsy.
Understanding Acute Tonsillitis
Acute tonsillitis is a condition that is characterized by pharyngitis, fever, malaise, and lymphadenopathy. It is caused by bacterial infections in over half of all cases, with Streptococcus pyogenes being the most common organism. The tonsils become swollen and may have yellow or white pustules. It is important to note that infectious mononucleosis may mimic the symptoms of acute tonsillitis.
Treatment for bacterial tonsillitis involves the use of penicillin-type antibiotics. Failure to treat bacterial tonsillitis may result in the formation of a local abscess known as quinsy.
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This question is part of the following fields:
- Respiratory System
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Question 25
Correct
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A 44-year-old heavy smoker presents with a productive cough and progressively worsening shortness of breath on exertion. The patient's spirometry results are forwarded to you in clinic for review.
Tidal volume (TV) = 400 mL.
Vital capacity (VC) = 3,300 mL.
Inspiratory capacity (IC) = 2,600 mL.
FEV1/FVC = 60%
Body plethysmography is undertaken, demonstrating a residual volume (RV) of 1,200 mL.
What is this patient's total lung capacity (TLC)?Your Answer: 4,500 mL
Explanation:To calculate the total lung capacity, one can add the vital capacity and residual volume. For example, if the vital capacity is 3300 mL and the residual volume is 1200 mL, the total lung capacity would be 4500 mL. It is important to note that tidal volume, inspiratory capacity, and the FEV1/FVC ratio are other measurements related to lung function. Residual volume refers to the amount of air left in the lungs after a maximal exhalation, while total lung capacity refers to the volume of air in the lungs after a maximal inhalation.
Understanding Lung Volumes in Respiratory Physiology
In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.
Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.
Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.
Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.
Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.
Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.
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This question is part of the following fields:
- Respiratory System
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Question 26
Incorrect
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During a consultant-led ward round in the early morning, a patient recovering from endovascular thrombectomy for acute mesenteric ischemia is examined. The reports indicate an embolus in the superior mesenteric artery.
What is the correct description of the plane at which the superior mesenteric artery branches off the abdominal aorta and its corresponding vertebral body?Your Answer: Subcostal plane - L3
Correct Answer: Transpyloric plane - L1
Explanation:The superior mesenteric artery originates from the abdominal aorta at the transpyloric plane, which is an imaginary axial plane located at the level of the L1 vertebral body and midway between the jugular notch and superior border of the pubic symphysis. Another transverse plane commonly used in anatomy is the subcostal plane, which passes through the 10th costal margin and the vertebral body L3. Additionally, the trans-tubercular plane, which is a horizontal plane passing through the iliac tubercles and in line with the 5th lumbar vertebrae, is often used to delineate abdominal regions in surface anatomy.
The Transpyloric Plane and its Anatomical Landmarks
The transpyloric plane is an imaginary horizontal line that passes through the body of the first lumbar vertebrae (L1) and the pylorus of the stomach. It is an important anatomical landmark used in clinical practice to locate various organs and structures in the abdomen.
Some of the structures that lie on the transpyloric plane include the left and right kidney hilum (with the left one being at the same level as L1), the fundus of the gallbladder, the neck of the pancreas, the duodenojejunal flexure, the superior mesenteric artery, and the portal vein. The left and right colic flexure, the root of the transverse mesocolon, and the second part of the duodenum also lie on this plane.
In addition, the upper part of the conus medullaris (the tapered end of the spinal cord) and the spleen are also located on the transpyloric plane. Knowing the location of these structures is important for various medical procedures, such as abdominal surgeries and diagnostic imaging.
Overall, the transpyloric plane serves as a useful reference point for clinicians to locate important anatomical structures in the abdomen.
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This question is part of the following fields:
- Respiratory System
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Question 27
Correct
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A 65-year-old man with a 45-pack-year history arrives at the hospital complaining of increased difficulty breathing and cachexia. Upon examination, a chest X-ray reveals an elevated left hemidiaphragm, enlarged hilar lymph nodes, and a significant opacification. Which structure is most likely to have been affected?
Your Answer: Left phrenic nerve
Explanation:It is unlikely that direct injury would result in the elevation of the left hemidiaphragm, especially since there is no history of trauma or surgery. However, damage to the long thoracic nerve could cause winging of the scapula due to weakened serratus anterior muscle. On the other hand, injury to the thoracodorsal nerve, which innervates the latissimus dorsi muscle, can lead to weakened shoulder adduction and is a common complication of axillary surgery.
The Phrenic Nerve: Origin, Path, and Supplies
The phrenic nerve is a crucial nerve that originates from the cervical spinal nerves C3, C4, and C5. It supplies the diaphragm and provides sensation to the central diaphragm and pericardium. The nerve passes with the internal jugular vein across scalenus anterior and deep to the prevertebral fascia of the deep cervical fascia.
The right phrenic nerve runs anterior to the first part of the subclavian artery in the superior mediastinum and laterally to the superior vena cava. In the middle mediastinum, it is located to the right of the pericardium and passes over the right atrium to exit the diaphragm at T8. On the other hand, the left phrenic nerve passes lateral to the left subclavian artery, aortic arch, and left ventricle. It passes anterior to the root of the lung and pierces the diaphragm alone.
Understanding the origin, path, and supplies of the phrenic nerve is essential in diagnosing and treating conditions that affect the diaphragm and pericardium.
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This question is part of the following fields:
- Respiratory System
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Question 28
Correct
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A 35-year-old man visits his GP with complaints of persistent cough and difficulty breathing for over four months. Despite not being a smoker, he is puzzled as to why his symptoms have not improved. Upon further investigation, he is diagnosed with chronic obstructive pulmonary disease (COPD). The GP suspects a genetic factor contributing to the early onset of the disease and orders blood tests. The results reveal a deficiency in a protein responsible for shielding lung cells from neutrophil elastase. What is the name of the deficient protein?
Your Answer: Alpha-1 antitrypsin
Explanation:COPD is typically found in older smokers, but non-smokers with A-1 antitrypsin deficiency may also develop the condition. This genetic condition is tested for with genetic and blood tests, as the protein it affects would normally protect lung cells from damage caused by neutrophil elastase. C1 inhibitor is not related to early onset COPD, but rather plays a role in hereditary angioedema. Plasminogen activator inhibitor-1 deficiency increases the risk of fibrinolysis, while surfactant protein D deficiency is associated with a higher likelihood of bacterial lung infections due to decreased ability of alveolar macrophages to bind to pathogens. Emphysema is primarily caused by uninhibited action of neutrophil elastase due to a1- antitrypsin deficiency, rather than elastin destruction.
Alpha-1 antitrypsin (A1AT) deficiency is a genetic condition that occurs when the liver does not produce enough of a protein called protease inhibitor (Pi). This protein is responsible for protecting cells from enzymes like neutrophil elastase. A1AT deficiency is inherited in an autosomal recessive or co-dominant manner and is located on chromosome 14. The alleles are classified by their electrophoretic mobility, with M being normal, S being slow, and Z being very slow. The normal genotype is PiMM, while heterozygous individuals have PiMZ. Homozygous PiSS individuals have 50% normal A1AT levels, while homozygous PiZZ individuals have only 10% normal A1AT levels.
A1AT deficiency is most commonly associated with panacinar emphysema, which is a type of chronic obstructive pulmonary disease (COPD). This is especially true for patients with the PiZZ genotype. Emphysema is more likely to occur in non-smokers with A1AT deficiency, but they may still pass on the gene to their children. In addition to lung problems, A1AT deficiency can also cause liver issues such as cirrhosis and hepatocellular carcinoma in adults, and cholestasis in children.
Diagnosis of A1AT deficiency involves measuring A1AT concentrations and performing spirometry to assess lung function. Management of the condition includes avoiding smoking and receiving supportive care such as bronchodilators and physiotherapy. Intravenous alpha1-antitrypsin protein concentrates may also be used. In severe cases, lung volume reduction surgery or lung transplantation may be necessary.
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This question is part of the following fields:
- Respiratory System
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Question 29
Incorrect
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An 80-year-old woman presents to the emergency department with a 2-day history of severe abdominal pain, accompanied by nausea and vomiting. Upon examination, she has a distended abdomen that is tender to the touch, and bowel sounds are infrequent. Her medical history includes a hysterectomy and cholecystectomy. A CT scan is ordered, which reveals a bowel obstruction at the L1 level. What is the most likely affected area?
Your Answer: Caecum
Correct Answer: Duodenum
Explanation:The 2nd segment of the duodenum is situated at the transpyloric plane, which corresponds to the level of L1 and is a significant anatomical reference point.
The Transpyloric Plane and its Anatomical Landmarks
The transpyloric plane is an imaginary horizontal line that passes through the body of the first lumbar vertebrae (L1) and the pylorus of the stomach. It is an important anatomical landmark used in clinical practice to locate various organs and structures in the abdomen.
Some of the structures that lie on the transpyloric plane include the left and right kidney hilum (with the left one being at the same level as L1), the fundus of the gallbladder, the neck of the pancreas, the duodenojejunal flexure, the superior mesenteric artery, and the portal vein. The left and right colic flexure, the root of the transverse mesocolon, and the second part of the duodenum also lie on this plane.
In addition, the upper part of the conus medullaris (the tapered end of the spinal cord) and the spleen are also located on the transpyloric plane. Knowing the location of these structures is important for various medical procedures, such as abdominal surgeries and diagnostic imaging.
Overall, the transpyloric plane serves as a useful reference point for clinicians to locate important anatomical structures in the abdomen.
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This question is part of the following fields:
- Respiratory System
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Question 30
Correct
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A premature baby is born and the anaesthetists are struggling to ventilate the lungs because of insufficient surfactant. How does Laplace's law explain the force pushing inwards on the walls of the alveolus caused by surface tension between two static fluids, such as air and water in the alveolus?
Your Answer: Inversely proportional to the radius of the alveolus
Explanation:The Relationship between Alveolar Size and Surface Tension in Respiratory Physiology
In respiratory physiology, the alveolus is often represented as a perfect sphere to apply Laplace’s law. According to this law, there is an inverse relationship between the size of the alveolus and the surface tension. This means that smaller alveoli experience greater force than larger alveoli for a given surface tension, and they will collapse first. This phenomenon explains why, when two balloons are attached together by their ends, the smaller balloon will empty into the bigger balloon.
In the lungs, this same principle applies to lung units, causing atelectasis and collapse when surfactant is not present. Surfactant is a substance that reduces surface tension, making it easier to expand the alveoli and preventing smaller alveoli from collapsing. Therefore, surfactant plays a crucial role in maintaining the proper functioning of the lungs and preventing respiratory distress. the relationship between alveolar size and surface tension is essential in respiratory physiology and can help in the development of treatments for lung diseases.
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This question is part of the following fields:
- Respiratory System
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Question 31
Incorrect
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A 55-year-old man is admitted to the ICU after emergency surgery for an abdominal aortic aneurysm. He presents with abdominal pain and diarrhea and is in a critical condition. Despite the absence of peritonism, which of the following arterial blood gas patterns is most likely to be observed?
Your Answer: pH 7.35, pO2 8.0, pCO2 5.2, Base excess 2, Lactate 1
Correct Answer: pH 7.20, pO2 9.0, pCO2 3.5, Base excess -10, Lactate 8
Explanation:It is probable that this individual is experiencing metabolic acidosis as a result of a mesenteric infarction.
Disorders of Acid-Base Balance
The acid-base nomogram is a useful tool for categorizing the various disorders of acid-base balance. Metabolic acidosis is the most common surgical acid-base disorder, characterized by a reduction in plasma bicarbonate levels. This can be caused by a gain of strong acid or loss of base, and is classified according to the anion gap. A normal anion gap indicates hyperchloraemic metabolic acidosis, which can be caused by gastrointestinal bicarbonate loss, renal tubular acidosis, drugs, or Addison’s disease. A raised anion gap indicates lactate, ketones, urate, or acid poisoning. Metabolic alkalosis, on the other hand, is usually caused by a rise in plasma bicarbonate levels due to a loss of hydrogen ions or a gain of bicarbonate. It is mainly caused by problems of the kidney or gastrointestinal tract. Respiratory acidosis is characterized by a rise in carbon dioxide levels due to alveolar hypoventilation, while respiratory alkalosis is caused by hyperventilation resulting in excess loss of carbon dioxide. These disorders have various causes, such as COPD, sedative drugs, anxiety, hypoxia, and pregnancy.
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This question is part of the following fields:
- Respiratory System
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Question 32
Correct
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A 59-year-old man comes to see his GP complaining of vertigo that has been going on for three days. He also reports experiencing left-sided ear pain and a change in his sense of taste, as well as constant ringing in his left ear. He took paracetamol on his own, but the vertigo persisted, so he decided to seek medical attention.
During the examination, the doctor observes that the man has a drooping left face with involvement of the forehead. Upon otoscopic examination, vesicles are seen in the external auditory canal of the left ear. A neurological examination is performed, which is normal except for the left facial paralysis.
What is the appropriate treatment for this man's condition?Your Answer: Oral acyclovir and corticosteroids
Explanation:Ramsay Hunt syndrome is treated with a combination of oral acyclovir and corticosteroids. This condition is caused by the varicella zoster virus, as evidenced by the presence of vesicles on the left ear and involvement of the seventh and eighth cranial nerves. Symptoms include facial paralysis and hearing impairments. Treatment typically involves a seven to ten day course of oral acyclovir and a five day course of corticosteroids, such as prednisolone.
It is important to note that oseltamivir (tamiflu) is an antiviral used for influenzae, while chloroquine is typically used for malaria. Amoxicillin is an antibiotic and is not effective in treating viral infections. While corticosteroids can provide relief from inflammation, they are not the primary treatment for Ramsay Hunt syndrome when used alone.
Understanding Ramsay Hunt Syndrome
Ramsay Hunt syndrome, also known as herpes zoster oticus, is a condition that occurs when the varicella zoster virus reactivates in the geniculate ganglion of the seventh cranial nerve. The first symptom of this syndrome is often auricular pain, followed by facial nerve palsy and a vesicular rash around the ear. Other symptoms may include vertigo and tinnitus.
To manage Ramsay Hunt syndrome, doctors typically prescribe oral acyclovir and corticosteroids. These medications can help reduce the severity of symptoms and prevent complications.
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This question is part of the following fields:
- Respiratory System
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Question 33
Correct
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A 12-year-old girl is referred to a respiratory specialist due to persistent episodes of shortness of breath. She also suffers from severe hay fever and eczema. After undergoing a peak expiratory flow test, signs of outflow obstruction of her lungs are detected. The doctor prescribes beclomethasone and salbutamol for her and advises her mother to keep her away from dust, as asthma is often linked to hypersensitivity to dust. Which type of hypersensitivity is associated with asthma?
Your Answer: Type 1 hypersensitivity
Explanation:Asthma is linked to type 1 hypersensitivity, which is caused by the binding of IgE to Mast cells, resulting in an inflammatory reaction. Other types of hypersensitivity include type 2, which involves the binding of IgG or IgM to cell surface antigens, type 3, which is immune complex-mediated, and type 4, which is T-cell mediated.
Asthma is a common respiratory disorder that affects both children and adults. It is characterized by chronic inflammation of the airways, resulting in reversible bronchospasm and airway obstruction. While asthma can develop at any age, it typically presents in childhood and may improve or resolve with age. However, it can also persist into adulthood and cause significant morbidity, with around 1,000 deaths per year in the UK.
Several risk factors can increase the likelihood of developing asthma, including a personal or family history of atopy, antenatal factors such as maternal smoking or viral infections, low birth weight, not being breastfed, exposure to allergens and air pollution, and the hygiene hypothesis. Patients with asthma may also suffer from other atopic conditions such as eczema and hay fever, and some may be sensitive to aspirin. Occupational asthma is also a concern for those exposed to allergens in the workplace.
Symptoms of asthma include coughing, dyspnea, wheezing, and chest tightness, with coughing often worse at night. Signs may include expiratory wheezing on auscultation and reduced peak expiratory flow rate. Diagnosis is typically made through spirometry, which measures the volume and speed of air during exhalation and inhalation.
Management of asthma typically involves the use of inhalers to deliver drug therapy directly to the airways. Short-acting beta-agonists such as salbutamol are the first-line treatment for relieving symptoms, while inhaled corticosteroids like beclometasone dipropionate and fluticasone propionate are used for daily maintenance therapy. Long-acting beta-agonists like salmeterol and leukotriene receptor antagonists like montelukast may also be used in combination with other medications. Maintenance and reliever therapy (MART) is a newer approach that combines ICS and a fast-acting LABA in a single inhaler for both daily maintenance and symptom relief. Recent guidelines recommend offering a leukotriene receptor antagonist instead of a LABA for patients on SABA + ICS whose asthma is not well controlled, and considering MART for those with poorly controlled asthma.
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This question is part of the following fields:
- Respiratory System
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Question 34
Incorrect
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You are clerking a 45-year-old patient on the neurosurgery ward who is scheduled to undergo a pituitary tumour removal surgery. During your conversation, the patient inquires about the procedure. As you are aware, the neurosurgeon gains access to the pituitary gland through the patient's nasal cavity, specifically through one of the paranasal sinuses. Can you identify which of the paranasal sinuses is situated on the roof of the posterior nasal cavity, below the pituitary gland?
Your Answer: Ethmoid air cells
Correct Answer: Sphenoid sinus
Explanation:Paranasal Air Sinuses and Carotid Sinus
The paranasal air sinuses are air-filled spaces found in the bones of the skull. They are named after the bone in which they are located and all communicate with the nasal cavity. The four paired paranasal air sinuses are the frontal sinuses, maxillary sinuses, ethmoid air cells, and sphenoid sinuses. The frontal sinuses are located above each eye on the forehead, while the maxillary sinuses are the largest and found in the maxillary bone below the orbit. The ethmoidal air cells are a collection of smaller air cells located lateral to the anterior superior nasal cavity, while the sphenoid sinuses are found in the posterior portion of the roof of the nasal cavity.
On the other hand, the carotid sinus is not a paranasal air sinus. It is a dilatation of the internal carotid artery, located just beyond the bifurcation of the common carotid artery. It contains baroreceptors that enable it to detect changes in arterial pressure.
Overall, understanding the location and function of these sinuses and the carotid sinus is important in various medical procedures and conditions.
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This question is part of the following fields:
- Respiratory System
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Question 35
Incorrect
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As the pregnancy progresses, at what stage does the foetus typically begin producing surfactant?
A mother has been informed that she will have to deliver her baby prematurely due to complications in the pregnancy. To decrease the chances of neonatal distress syndrome, doctors have administered steroids to stimulate surfactant production in the foetus. They clarify that the foetus is already generating its own surfactant, and these steroids will enhance the process.Your Answer: Week 30
Correct Answer: Week 22
Explanation:Lung development in humans begins at week 4 with the formation of the respiratory diverticulum. By week 10, the lungs start to grow as tertiary bronchial buds form. Terminal bronchioles begin to form around week 18. The saccular stage of lung development, which marks the earliest viability for a human fetus, occurs at around 22-24 weeks when type 2 alveolar cells start producing surfactant. By week 30, the primary alveoli form as the mesenchyme surrounding the lungs becomes highly vascular.
The Importance of Pulmonary Surfactant in Breathing
Pulmonary surfactant is a substance composed of phospholipids, carbohydrates, and proteins that is released by type 2 pneumocytes. Its main component, dipalmitoyl phosphatidylcholine (DPPC), plays a crucial role in reducing alveolar surface tension. This substance is first detectable around 28 weeks and increases in concentration as the alveoli decrease in size. This helps prevent the alveoli from collapsing and reduces the muscular force needed to expand the lungs, ultimately decreasing the work of breathing. Additionally, pulmonary surfactant lowers the elastic recoil at low lung volumes, preventing the alveoli from collapsing at the end of each expiration. Overall, pulmonary surfactant is essential in maintaining proper lung function and preventing respiratory distress.
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This question is part of the following fields:
- Respiratory System
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Question 36
Correct
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A 49-year-old woman of African descent visits her primary care physician with concerns about a lump in her neck that has been present for a week. She reports no significant increase in size and denies any pain or difficulty swallowing. The patient has no notable medical history, except for a visit to the eye doctor last year for a red-eye that required treatment with topical steroid drops. During the examination, the doctor observes some red, tender nodules on the patient's shin, which the patient says come and go and do not cause much discomfort. A chest x-ray reveals bilateral hilar lymphadenopathy with no other significant findings. What is typically linked to this patient's condition?
Your Answer: Elevated angiotensin-converting enzyme levels
Explanation:Sarcoidosis is likely in this patient based on their symptoms and examination findings, including a neck lump, tender nodules on the shin, and a history of red-eye. Bilateral lymphadenopathy on chest X-ray further supports the diagnosis, as does the presence of elevated angiotensin-converting enzyme levels, which are commonly seen in sarcoidosis. Hypercalcemia, fatigue, and uveitis are also associated with sarcoidosis, while exposure to silica is not supported by this patient’s presentation.
Investigating Sarcoidosis
Sarcoidosis is a disease that does not have a single diagnostic test, and therefore, diagnosis is mainly based on clinical observations. Although ACE levels may be used to monitor disease activity, they are not reliable in diagnosing sarcoidosis due to their low sensitivity and specificity. Routine blood tests may show hypercalcemia and a raised ESR.
A chest x-ray is a common investigation for sarcoidosis and may reveal different stages of the disease. Stage 0 is normal, stage 1 shows bilateral hilar lymphadenopathy (BHL), stage 2 shows BHL and interstitial infiltrates, stage 3 shows diffuse interstitial infiltrates only, and stage 4 shows diffuse fibrosis. Other investigations, such as spirometry, may show a restrictive defect, while a tissue biopsy may reveal non-caseating granulomas. However, the Kveim test, which involves injecting part of the spleen from a patient with known sarcoidosis under the skin, is no longer performed due to concerns about cross-infection.
In addition, a gallium-67 scan is not routinely used to investigate sarcoidosis. CT scans may also be used to investigate sarcoidosis, and they may show diffuse areas of nodularity predominantly in a peribronchial distribution with patchy areas of consolidation, particularly in the upper lobes. Ground glass opacities may also be present, but there are no gross reticular changes to suggest fibrosis.
Overall, investigating sarcoidosis involves a combination of clinical observations, blood tests, chest x-rays, and other investigations such as spirometry and tissue biopsy. CT scans may also be used to provide more detailed information about the disease.
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This question is part of the following fields:
- Respiratory System
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Question 37
Correct
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A 32-year-old male presents to the GP clinic complaining of vertigo. He mentions having a mild upper respiratory tract infection one week prior. Which structure is most likely responsible for the accompanying nausea?
Your Answer: Vestibular system of the inner ear
Explanation:Based on the symptoms presented, it is probable that the patient is experiencing viral labyrinthitis, which is a common condition that occurs after an upper respiratory tract infection. This condition causes inflammation in the vestibular system of the inner ear, leading to confusion or failure of proprioceptive signals to the brain, resulting in vertigo.
During retching, the antrum of the stomach contracts while the cardia and fundus relax. Although vagal stimulation can arise from the stomach, it does not cause the spinning sensation associated with vertigo.
The area postrema is located in the medulla and contains the chemoreceptor trigger zone, which is involved in receiving and transmitting signals related to the vomiting reflex. However, the specific signal for vertigo arises from the vestibular system. The pons also plays a role in communicating sensory inputs related to vomiting.
Vertigo is a condition characterized by a false sensation of movement in the body or environment. There are various causes of vertigo, each with its own unique characteristics. Viral labyrinthitis, for example, is typically associated with a recent viral infection, sudden onset, nausea and vomiting, and possible hearing loss. Vestibular neuronitis, on the other hand, is characterized by recurrent vertigo attacks lasting hours or days, but with no hearing loss. Benign paroxysmal positional vertigo is triggered by changes in head position and lasts for only a few seconds. Meniere’s disease, meanwhile, is associated with hearing loss, tinnitus, and a feeling of fullness or pressure in the ears. Elderly patients with vertigo may be experiencing vertebrobasilar ischaemia, which is accompanied by dizziness upon neck extension. Acoustic neuroma, which is associated with hearing loss, vertigo, and tinnitus, is also a possible cause of vertigo. Other causes include posterior circulation stroke, trauma, multiple sclerosis, and ototoxicity from medications like gentamicin.
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This question is part of the following fields:
- Respiratory System
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Question 38
Incorrect
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A 35-year-old female smoker presents with acute severe asthma.
The patient's SaO2 levels are at 91% even with 15 L of oxygen, and her pO2 is at 8.2 kPa (10.5-13). There is widespread expiratory wheezing throughout her chest.
The medical team administers IV hydrocortisone, 100% oxygen, and 5 mg of nebulised salbutamol and 500 micrograms of nebulised ipratropium, but there is little response. Nebulisers are repeated 'back-to-back,' but the patient remains tachypnoeic with wheezing, although there is good air entry.
What should be the next step in the patient's management?Your Answer: Oral prednisolone
Correct Answer: IV Magnesium
Explanation:Acute Treatment of Asthma
When dealing with acute asthma, the initial approach should be SOS, which stands for Salbutamol, Oxygen, and Steroids (IV). It is also important to organize a CXR to rule out pneumothorax. If the patient is experiencing bronchoconstriction, further efforts to treat it should be considered. If the patient is tiring or has a silent chest, ITU review may be necessary. Magnesium is recommended at a dose of 2 g over 30 minutes to promote bronchodilation, as low magnesium levels in bronchial smooth muscle can favor bronchoconstriction. IV theophylline may also be considered, but magnesium is typically preferred. While IV antibiotics may be necessary, promoting bronchodilation should be the initial focus. IV potassium may also be required as beta agonists can push down potassium levels. Oral prednisolone can wait, as IV hydrocortisone is already part of the SOS approach. Non-invasive ventilation is not recommended for the acute management of asthma.
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This question is part of the following fields:
- Respiratory System
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Question 39
Correct
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A 65-year-old male with a diagnosis of lung cancer presents with fatigue and lightheadedness. Upon examination, the following results are obtained:
Plasma sodium concentration 115 mmol/L (137-144)
Potassium 3.5 mmol/L (3.5-4.9)
Urea 3.2 mmol/L (2.5-7.5)
Creatinine 67 µmol/L (60-110)
What is the probable reason for his symptoms based on these findings?Your Answer: Syndrome of inappropriate ADH secretion
Explanation:Syndrome of Inappropriate ADH Secretion
Syndrome of inappropriate ADH secretion (SIADH) is a condition characterized by low levels of sodium in the blood. This is caused by the overproduction of antidiuretic hormone (ADH) by the posterior pituitary gland. Tumors such as bronchial carcinoma can cause the ectopic elaboration of ADH, leading to dilutional hyponatremia. The diagnosis of SIADH is one of exclusion, but it can be supported by a high urine sodium concentration with high urine osmolality.
Hypoadrenalism is less likely to cause hyponatremia, as it is usually associated with hyperkalemia and mild hyperuricemia. On the other hand, diabetes insipidus is a condition where the kidneys are unable to reabsorb water, leading to excessive thirst and urination.
It is important to diagnose and treat SIADH promptly to prevent complications such as seizures, coma, and even death. Treatment options include fluid restriction, medications to block the effects of ADH, and addressing the underlying cause of the condition.
In conclusion, SIADH is a condition that can cause low levels of sodium in the blood due to the overproduction of ADH. It is important to differentiate it from other conditions that can cause hyponatremia and to treat it promptly to prevent complications.
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This question is part of the following fields:
- Respiratory System
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Question 40
Correct
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A 58-year-old man comes to the GP complaining of wheezing, coughing, and shortness of breath. He has a smoking history of 35 pack-years but has reduced his smoking recently.
The GP orders spirometry, which confirms a diagnosis of chronic obstructive pulmonary disease. The results also show an elevated functional residual capacity.
What is the method used to calculate this metric?Your Answer: Expiratory reserve volume + residual volume
Explanation:Understanding Lung Volumes in Respiratory Physiology
In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.
Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.
Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.
Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.
Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.
Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.
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This question is part of the following fields:
- Respiratory System
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Question 41
Incorrect
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A 65-year-old man with uncontrolled diabetes complains of severe otalgia and headaches. During examination, granulation tissue is observed in the external auditory meatus. What is the probable causative agent of the infection?
Your Answer: Staphylococcus aureus
Correct Answer: Pseudomonas aeruginosa
Explanation:The primary cause of malignant otitis externa is typically Pseudomonas aeruginosa. Symptoms of this condition include intense pain, headaches, and the presence of granulation tissue in the external auditory meatus. Individuals with diabetes mellitus are at a higher risk for developing this condition.
Malignant Otitis Externa: A Rare but Serious Infection
Malignant otitis externa is a type of ear infection that is uncommon but can be serious. It is typically found in individuals who are immunocompromised, with 90% of cases occurring in diabetics. The infection starts in the soft tissues of the external auditory meatus and can progress to involve the soft tissues and bony ear canal, eventually leading to temporal bone osteomyelitis.
Key features in the patient’s history include diabetes or immunosuppression, severe and persistent ear pain, temporal headaches, and purulent otorrhea. In some cases, patients may also experience dysphagia, hoarseness, and facial nerve dysfunction.
Diagnosis is typically done through a CT scan, and non-resolving otitis externa with worsening pain should be referred urgently to an ENT specialist. Treatment involves intravenous antibiotics that cover pseudomonal infections.
In summary, malignant otitis externa is a rare but serious infection that requires prompt diagnosis and treatment. Patients with diabetes or immunosuppression should be particularly vigilant for symptoms and seek medical attention if they experience persistent ear pain or other related symptoms.
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This question is part of the following fields:
- Respiratory System
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Question 42
Incorrect
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A 29-year-old man visits his primary care physician with complaints of a malodorous discharge from his right ear for the past 3 weeks. The patient also reports experiencing ear pain for the past 2 weeks and occasional mild dizziness. Upon examination, the skin around the ear and pinna appear normal, but the ear canal is filled with debris. After removing the debris, a small perforation and waxy debris are observed on the tympanic membrane.
The Rinne test indicates that bone conduction is better than air conduction on the right, and the Weber test shows sound lateralization to the right. The patient has no significant medical history and has never presented with an ear problem before.
What is the most likely condition based on this patient's clinical presentation?Your Answer: Otitis media
Correct Answer: Cholesteatoma
Explanation:Cholesteatoma is a growth of non-cancerous squamous epithelium that can be observed as an ‘attic crust’ during otoscopy. This patient is displaying symptoms consistent with cholesteatoma, including ear discharge, earache, conductive hearing loss, and dizziness, which suggests that the inner ear has also been affected. It is important to distinguish cholesteatoma from otitis externa, as failure to diagnose cholesteatoma can lead to serious complications. Cholesteatoma can erode the ossicles bones, damage the inner ear and vestibulocochlear nerve, and even result in brain infections if it erodes through the skull bone.
Otitis externa is an inflammation of the outer ear canal that causes ear pain, which worsens with movement of the outer ear. It is often caused by the use of earplugs or swimming in unclean water. Otitis media is an inflammation of the middle ear that can lead to fluid accumulation and perforation of the tympanic membrane. It is common in children and often follows a viral upper respiratory tract infection. Myringitis is a condition associated with otitis media that causes small vesicles or cysts to form on the surface of the eardrum, resulting in severe pain and hearing impairment. It is caused by viral or bacterial infections and is treated with pain relief and antibiotics.
Understanding Cholesteatoma
Cholesteatoma is a benign growth of squamous epithelium that can cause damage to the skull base. It is most commonly found in individuals between the ages of 10 and 20 years old. Those born with a cleft palate are at a higher risk of developing cholesteatoma, with a 100-fold increase in risk.
The main symptoms of cholesteatoma include a persistent discharge with a foul odor and hearing loss. Other symptoms may occur depending on the extent of the growth, such as vertigo, facial nerve palsy, and cerebellopontine angle syndrome.
During otoscopy, a characteristic attic crust may be seen in the uppermost part of the eardrum.
Management of cholesteatoma involves referral to an ear, nose, and throat specialist for surgical removal. Early detection and treatment are important to prevent further damage to the skull base and surrounding structures.
In summary, cholesteatoma is a non-cancerous growth that can cause significant damage if left untreated. It is important to be aware of the symptoms and seek medical attention promptly if they occur.
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This question is part of the following fields:
- Respiratory System
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Question 43
Correct
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A 29-year-old cyclist is brought to the emergency department by air ambulance following a car collision. She was intubated at the scene and currently has a Glasgow Coma Score of 8. Where is the control and regulation of the respiratory centers located?
Your Answer: Brainstem
Explanation:The brainstem houses the respiratory centres, which are responsible for regulating various aspects of breathing. These centres are located in the upper pons, lower pons and medulla oblongata.
The thalamus plays a role in sensory, motor and cognitive functions, and its axons connect with the cerebral cortex. The cerebellum coordinates voluntary movements and helps maintain balance and posture. The parietal lobe processes sensory information, including discrimination and body orientation. The primary visual cortex is located in the occipital lobe.
The Control of Ventilation in the Human Body
The control of ventilation in the human body is a complex process that involves various components working together to regulate the respiratory rate and depth of respiration. The respiratory centres, chemoreceptors, lung receptors, and muscles all play a role in this process. The automatic, involuntary control of respiration occurs from the medulla, which is responsible for controlling the respiratory rate and depth of respiration.
The respiratory centres consist of the medullary respiratory centre, apneustic centre, and pneumotaxic centre. The medullary respiratory centre has two groups of neurons, the ventral group, which controls forced voluntary expiration, and the dorsal group, which controls inspiration. The apneustic centre, located in the lower pons, stimulates inspiration and activates and prolongs inhalation. The pneumotaxic centre, located in the upper pons, inhibits inspiration at a certain point and fine-tunes the respiratory rate.
Ventilatory variables, such as the levels of pCO2, are the most important factors in ventilation control, while levels of O2 are less important. Peripheral chemoreceptors, located in the bifurcation of carotid arteries and arch of the aorta, respond to changes in reduced pO2, increased H+, and increased pCO2 in arterial blood. Central chemoreceptors, located in the medulla, respond to increased H+ in brain interstitial fluid to increase ventilation. It is important to note that the central receptors are not influenced by O2 levels.
Lung receptors also play a role in the control of ventilation. Stretch receptors respond to lung stretching, causing a reduced respiratory rate, while irritant receptors respond to smoke, causing bronchospasm. J (juxtacapillary) receptors are also involved in the control of ventilation. Overall, the control of ventilation is a complex process that involves various components working together to regulate the respiratory rate and depth of respiration.
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This question is part of the following fields:
- Respiratory System
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Question 44
Incorrect
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A 72-year-old man is admitted to the hospital with symptoms of the flu, confusion, and vomiting. His finger prick glucose levels are within normal range. The physician suspects that the patient's living conditions, which include poor housing and lack of support at home, may have contributed to his symptoms.
What physiological response is expected in this patient?Your Answer: A decreased affinity of haemoglobin for oxygen
Correct Answer: An increased affinity of haemoglobin for oxygen
Explanation:Methaemoglobin causes a leftward shift of the oxygen dissociation curve, indicating an increased affinity of haemoglobin for oxygen. This results in reduced offloading of oxygen into the tissues, leading to decreased oxygen delivery. It is important to understand the oxygen-dissociation curve and the effects of carbon monoxide poisoning, which causes increased oxygen binding to methaemoglobin. A rightward shift of the curve indicates increased oxygen delivery to the tissues, which is not the case in methaemoglobinemia.
Understanding the Oxygen Dissociation Curve
The oxygen dissociation curve is a graphical representation of the relationship between the percentage of saturated haemoglobin and the partial pressure of oxygen in the blood. It is not influenced by the concentration of haemoglobin. The curve can shift to the left or right, indicating changes in oxygen delivery to tissues. When the curve shifts to the left, there is increased saturation of haemoglobin with oxygen, resulting in decreased oxygen delivery to tissues. Conversely, when the curve shifts to the right, there is reduced saturation of haemoglobin with oxygen, leading to enhanced oxygen delivery to tissues.
The L rule is a helpful mnemonic to remember the factors that cause a shift to the left, resulting in lower oxygen delivery. These factors include low levels of hydrogen ions (alkali), low partial pressure of carbon dioxide, low levels of 2,3-diphosphoglycerate, and low temperature. On the other hand, the mnemonic ‘CADET, face Right!’ can be used to remember the factors that cause a shift to the right, leading to raised oxygen delivery. These factors include carbon dioxide, acid, 2,3-diphosphoglycerate, exercise, and temperature.
Understanding the oxygen dissociation curve is crucial in assessing the oxygen-carrying capacity of the blood and the delivery of oxygen to tissues. By knowing the factors that can shift the curve to the left or right, healthcare professionals can make informed decisions in managing patients with respiratory and cardiovascular diseases.
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This question is part of the following fields:
- Respiratory System
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Question 45
Correct
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Which of the following paraneoplastic manifestations is the LEAST frequent in individuals diagnosed with squamous cell lung carcinoma?
Your Answer: Lambert-Eaton syndrome
Explanation:Small cell lung cancer is strongly associated with Lambert-Eaton syndrome, while squamous cell lung cancer is more commonly associated with paraneoplastic features such as PTHrp, clubbing, and HPOA.
Lung cancer can present with paraneoplastic features, which are symptoms caused by the cancer but not directly related to the tumor itself. Small cell lung cancer can cause the secretion of ADH and, less commonly, ACTH, which can lead to hypertension, hyperglycemia, hypokalemia, alkalosis, and muscle weakness. Lambert-Eaton syndrome is also associated with small cell lung cancer. Squamous cell lung cancer can cause the secretion of parathyroid hormone-related protein, leading to hypercalcemia, as well as clubbing and hypertrophic pulmonary osteoarthropathy. Adenocarcinoma can cause gynecomastia and hypertrophic pulmonary osteoarthropathy. Hypertrophic pulmonary osteoarthropathy is a painful condition involving the proliferation of periosteum in the long bones. Although traditionally associated with squamous cell carcinoma, some studies suggest that adenocarcinoma is the most common cause.
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This question is part of the following fields:
- Respiratory System
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Question 46
Correct
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A 59-year-old man comes to you with a dry cough that has been going on for three months and recent episodes of haemoptysis. He stopped smoking five years ago and has had two bouts of pneumonia in his left lower lobe in the last year. On examination, he is apyrexial and there are no notable findings.
What would be your first step in investigating this patient?Your Answer: Chest x ray
Explanation:Diagnosis of Bronchial Carcinoma
The patient’s medical history indicates the possibility of bronchial carcinoma. The most appropriate initial investigation to confirm this diagnosis is a chest x-ray. Other tests such as blood cultures may not be useful for an apyrexial patient. However, additional investigations may be considered after the chest x-ray. It is important to prioritize the chest x-ray as the first line investigation to detect any abnormalities in the lungs. Proper diagnosis is crucial for timely treatment and management of bronchial carcinoma.
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This question is part of the following fields:
- Respiratory System
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Question 47
Incorrect
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Which one of the following nerves conveys sensory information from the nasal mucosa?
Your Answer: None of the above
Correct Answer: Laryngeal branches of the vagus
Explanation:The larynx receives sensory information from the laryngeal branches of the vagus.
Anatomy of the Larynx
The larynx is located in the front of the neck, between the third and sixth cervical vertebrae. It is made up of several cartilaginous segments, including the paired arytenoid, corniculate, and cuneiform cartilages, as well as the single thyroid, cricoid, and epiglottic cartilages. The cricoid cartilage forms a complete ring. The laryngeal cavity extends from the laryngeal inlet to the inferior border of the cricoid cartilage and is divided into three parts: the laryngeal vestibule, the laryngeal ventricle, and the infraglottic cavity.
The vocal folds, also known as the true vocal cords, control sound production. They consist of the vocal ligament and the vocalis muscle, which is the most medial part of the thyroarytenoid muscle. The glottis is composed of the vocal folds, processes, and rima glottidis, which is the narrowest potential site within the larynx.
The larynx is also home to several muscles, including the posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid, transverse and oblique arytenoids, vocalis, and cricothyroid muscles. These muscles are responsible for various actions, such as abducting or adducting the vocal folds and relaxing or tensing the vocal ligament.
The larynx receives its arterial supply from the laryngeal arteries, which are branches of the superior and inferior thyroid arteries. Venous drainage is via the superior and inferior laryngeal veins. Lymphatic drainage varies depending on the location within the larynx, with the vocal cords having no lymphatic drainage and the supraglottic and subglottic parts draining into different lymph nodes.
Overall, understanding the anatomy of the larynx is important for proper diagnosis and treatment of various conditions affecting this structure.
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This question is part of the following fields:
- Respiratory System
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Question 48
Correct
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A 35-year-old pregnant woman undergoes an ABG test. What is the anticipated outcome for a healthy pregnant woman?
Your Answer: Compensated respiratory alkalosis
Explanation:During pregnancy, a woman’s increased tidal volume leads to a decrease in carbon dioxide levels, resulting in alkalosis. This is because carbon dioxide generates acid, and reduced levels of it lead to a decrease in acid. The kidneys eventually adapt to this change by reducing the amount of alkaline bicarbonate in the body. Therefore, pregnancy causes a compensated respiratory alkalosis.
If a woman’s bicarbonate levels remain normal, she would have simple respiratory alkalosis.
On the other hand, if a woman produces excess acid, she would have metabolic acidosis, which is the opposite of what occurs during pregnancy.
Arterial Blood Gas Interpretation: A 5-Step Approach
Arterial blood gas interpretation is a crucial aspect of patient care, particularly in critical care settings. The Resuscitation Council (UK) recommends a 5-step approach to interpreting arterial blood gas results. The first step is to assess the patient’s overall condition. The second step is to determine if the patient is hypoxaemic, with a PaO2 on air of less than 10 kPa. The third step is to assess if the patient is acidaemic (pH <7.35) or alkalaemic (pH >7.45).
The fourth step is to evaluate the respiratory component of the arterial blood gas results. A PaCO2 level greater than 6.0 kPa suggests respiratory acidosis, while a PaCO2 level less than 4.7 kPa suggests respiratory alkalosis. The fifth step is to assess the metabolic component of the arterial blood gas results. A bicarbonate level less than 22 mmol/l or a base excess less than -2mmol/l suggests metabolic acidosis, while a bicarbonate level greater than 26 mmol/l or a base excess greater than +2mmol/l suggests metabolic alkalosis.
To remember the relationship between pH, PaCO2, and bicarbonate, the acronym ROME can be used. Respiratory acidosis or alkalosis is opposite to the pH level, while metabolic acidosis or alkalosis is equal to the pH level. This 5-step approach and the ROME acronym can aid healthcare professionals in interpreting arterial blood gas results accurately and efficiently.
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This question is part of the following fields:
- Respiratory System
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Question 49
Correct
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Brenda is a 36-year-old woman who presents with tachypnoea. This occurred whilst she was seated. Her only medical history is asthma for which she takes salbutamol. On examination, her respiratory rate is 28 breaths/minute, heart rate 100bpm, Her chest is resonant on percussion and lung sounds are normal. Her chest X-ray is normal. You obtain her arterial blood gas sample results which show the following:
pH 7.55
PaCO2 4.2 kPa
PaO2 10 kPa
HCO3 24 mmol/l
What could have caused the acid-base imbalance in Brenda's case?Your Answer: Panic attack
Explanation:Although panic attacks can cause tachypnea and a decrease in partial pressure of carbon dioxide, the acid-base disturbance that would result from this situation is not included as one of the answer choices.
Respiratory Alkalosis: Causes and Examples
Respiratory alkalosis is a condition that occurs when the blood pH level rises above the normal range due to excessive breathing. This can be caused by various factors, including anxiety, pulmonary embolism, CNS disorders, altitude, and pregnancy. Salicylate poisoning can also lead to respiratory alkalosis, but it may also cause metabolic acidosis in the later stages. In this case, the respiratory centre is stimulated early, leading to respiratory alkalosis, while the direct acid effects of salicylates combined with acute renal failure may cause acidosis later on. It is important to identify the underlying cause of respiratory alkalosis to determine the appropriate treatment. Proper management can help prevent complications and improve the patient’s overall health.
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This question is part of the following fields:
- Respiratory System
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Question 50
Incorrect
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A middle-aged woman with myasthenia gravis experiences a myasthenic crisis leading to respiratory failure. Which nerve root is most commonly affected in this scenario?
Your Answer: T1
Correct Answer: C4
Explanation:The phrenic nerve receives input from C3, C4, and C5, which is essential for keeping the diaphragm functioning properly. In cases of medical emergencies, mechanical ventilation is often the first-line management. C2 primarily innervates muscles in the neck, while C7 and T1 are part of the brachial plexus and contribute to the formation of nerves in the upper limb.
The Phrenic Nerve: Origin, Path, and Supplies
The phrenic nerve is a crucial nerve that originates from the cervical spinal nerves C3, C4, and C5. It supplies the diaphragm and provides sensation to the central diaphragm and pericardium. The nerve passes with the internal jugular vein across scalenus anterior and deep to the prevertebral fascia of the deep cervical fascia.
The right phrenic nerve runs anterior to the first part of the subclavian artery in the superior mediastinum and laterally to the superior vena cava. In the middle mediastinum, it is located to the right of the pericardium and passes over the right atrium to exit the diaphragm at T8. On the other hand, the left phrenic nerve passes lateral to the left subclavian artery, aortic arch, and left ventricle. It passes anterior to the root of the lung and pierces the diaphragm alone.
Understanding the origin, path, and supplies of the phrenic nerve is essential in diagnosing and treating conditions that affect the diaphragm and pericardium.
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This question is part of the following fields:
- Respiratory System
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Question 51
Incorrect
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A 65-year-old man presents with respiratory symptoms and is referred to his primary care physician for pulmonary function testing. The estimated vital capacity is 3.5 liters. What does the measurement of vital capacity involve?
Your Answer: Tidal volume + Functional residual capacity
Correct Answer: Inspiratory reserve volume + Tidal volume + Expiratory reserve volume
Explanation:Understanding Lung Volumes in Respiratory Physiology
In respiratory physiology, lung volumes can be measured to determine the amount of air that moves in and out of the lungs during breathing. The diagram above shows the different lung volumes that can be measured.
Tidal volume (TV) refers to the amount of air that is inspired or expired with each breath at rest. In males, the TV is 500ml while in females, it is 350ml.
Inspiratory reserve volume (IRV) is the maximum volume of air that can be inspired at the end of a normal tidal inspiration. The inspiratory capacity is the sum of TV and IRV. On the other hand, expiratory reserve volume (ERV) is the maximum volume of air that can be expired at the end of a normal tidal expiration.
Residual volume (RV) is the volume of air that remains in the lungs after maximal expiration. It increases with age and can be calculated by subtracting ERV from FRC. Speaking of FRC, it is the volume in the lungs at the end-expiratory position and is equal to the sum of ERV and RV.
Vital capacity (VC) is the maximum volume of air that can be expired after a maximal inspiration. It decreases with age and can be calculated by adding inspiratory capacity and ERV. Lastly, total lung capacity (TLC) is the sum of vital capacity and residual volume.
Physiological dead space (VD) is calculated by multiplying tidal volume by the difference between arterial carbon dioxide pressure (PaCO2) and end-tidal carbon dioxide pressure (PeCO2) and then dividing the result by PaCO2.
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This question is part of the following fields:
- Respiratory System
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Question 52
Incorrect
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An 80-year-old man has been referred to the respiratory clinic due to a persistent dry cough and hoarse voice for the last 5 months. He reports feeling like he has lost some weight as his clothes feel loose. Although he has no significant past medical history, he has a 30-pack-year smoking history. During the examination, left-sided miosis and ptosis are noted. What is the probable location of the lung lesion?
Your Answer: Lung periphery
Correct Answer: Lung apex
Explanation:The patient’s persistent cough, significant smoking history, and weight loss are red flag symptoms of lung cancer. Additionally, the hoarseness of voice suggests that the recurrent laryngeal nerve is being suppressed, likely due to a Pancoast tumor located in the apex of the lung. The presence of Horner’s syndrome further supports this diagnosis. Mesothelioma, which is more common in patients with a history of asbestos exposure, typically presents with shortness of breath, chest wall pain, and finger clubbing. A hamartoma, a benign tumor made up of tissue such as cartilage, connective tissue, and fat, is unlikely given the patient’s red flags for malignant disease. Small cell carcinomas, typically found in the center of the lungs, may present with a perihilar mass and paraneoplastic syndromes due to ectopic hormone secretion. Lung cancers within the bronchi can obstruct airways and cause respiratory symptoms such as cough and shortness of breath, but not hoarseness.
Lung Cancer Symptoms and Complications
Lung cancer is a serious condition that can cause a range of symptoms and complications. Some of the most common symptoms include a persistent cough, haemoptysis (coughing up blood), dyspnoea (shortness of breath), chest pain, weight loss and anorexia, and hoarseness. In some cases, patients may also experience supraclavicular lymphadenopathy or persistent cervical lymphadenopathy, as well as clubbing and a fixed, monophonic wheeze.
In addition to these symptoms, lung cancer can also cause a range of paraneoplastic features. These may include the secretion of ADH, ACTH, or parathyroid hormone-related protein (PTH-rp), which can cause hypercalcaemia, hypertension, hyperglycaemia, hypokalaemia, alkalosis, muscle weakness, and other complications. Other paraneoplastic features may include Lambert-Eaton syndrome, hypertrophic pulmonary osteoarthropathy (HPOA), hyperthyroidism due to ectopic TSH, and gynaecomastia.
Complications of lung cancer may include hoarseness, stridor, and superior vena cava syndrome. Patients may also experience a thrombocytosis, which can be detected through blood tests. Overall, it is important to be aware of the symptoms and complications of lung cancer in order to seek prompt medical attention and receive appropriate treatment.
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This question is part of the following fields:
- Respiratory System
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Question 53
Incorrect
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A 35-year-old female presents with recurrent episodes of severe vertigo that have been disabling. She experiences these episodes multiple times a day, with each one lasting for about 10-20 minutes. Along with the vertigo, she also experiences ringing in both ears, nausea, and vomiting. She has noticed a change in her hearing in both ears, with difficulty hearing at times and normal hearing at other times. Additionally, she reports increased pressure in her ears. During the examination, you notice a painless rash behind her ear that has been present for many years.
What is the most likely diagnosis?Your Answer: Benign paroxysmal positional vertigo
Correct Answer: Meniere’s disease
Explanation:Suspect Meniere’s disease in a patient presenting with vertigo, tinnitus, and fluctuating sensorineural hearing loss. Acoustic neuroma would present with additional symptoms such as facial numbness and loss of corneal reflex. Herpes Zoster Oticus (Ramsey Hunt syndrome) would present with facial palsy and a painless rash. Vestibular neuronitis would have longer episodes of vertigo, nausea, and vomiting, but no hearing loss. Benign paroxysmal positional vertigo would have brief episodes of vertigo after sudden head movements.
Meniere’s disease is a condition that affects the inner ear and its cause is unknown. It is more commonly seen in middle-aged adults but can occur at any age and affects both men and women equally. The condition is characterized by the excessive pressure and progressive dilation of the endolymphatic system. The main symptoms of Meniere’s disease are recurrent episodes of vertigo, tinnitus, and sensorineural hearing loss. Vertigo is usually the most prominent symptom, but patients may also experience a sensation of aural fullness or pressure, nystagmus, and a positive Romberg test. These episodes can last from minutes to hours and are typically unilateral, but bilateral symptoms may develop over time.
The natural history of Meniere’s disease is that symptoms usually resolve in the majority of patients after 5-10 years. However, most patients will be left with some degree of hearing loss, and psychological distress is common. ENT assessment is required to confirm the diagnosis, and patients should inform the DVLA as the current advice is to cease driving until satisfactory control of symptoms is achieved. Acute attacks can be managed with buccal or intramuscular prochlorperazine, and admission to the hospital may be required. Prevention strategies include the use of betahistine and vestibular rehabilitation exercises, which may be beneficial.
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This question is part of the following fields:
- Respiratory System
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Question 54
Incorrect
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A 26-year-old woman comes to your clinic complaining of feeling dizzy for the past two days. She describes a sensation of the room spinning and has been experiencing nausea. The dizziness is relieved when she lies down and has no apparent triggers. She denies any hearing loss or aural fullness and is otherwise healthy. Upon examination, she has no fever and otoscopy reveals no abnormalities. You suspect she may have viral labyrinthitis and prescribe prochlorperazine to alleviate her vertigo symptoms. What class of antiemetic does prochlorperazine belong to?
Your Answer: Antimuscarinic
Correct Answer: Dopamine receptor antagonist
Explanation:Prochlorperazine belongs to a class of drugs known as dopamine receptor antagonists, which work by inhibiting stimulation of the chemoreceptor trigger zone (CTZ) through D2 receptors. Other drugs in this class include domperidone, metoclopramide, and olanzapine.
Antihistamine antiemetics, such as cyclizine and promethazine, are H1 histamine receptor antagonists.
5-HT3 receptor antagonists, such as ondansetron and granisetron, are effective both centrally and peripherally. They work by blocking serotonin receptors in the central nervous system and gastrointestinal tract.
Antimuscarinic antiemetics are anticholinergic drugs, with hyoscine (scopolamine) being a common example.
Vertigo is a condition characterized by a false sensation of movement in the body or environment. There are various causes of vertigo, each with its own unique characteristics. Viral labyrinthitis, for example, is typically associated with a recent viral infection, sudden onset, nausea and vomiting, and possible hearing loss. Vestibular neuronitis, on the other hand, is characterized by recurrent vertigo attacks lasting hours or days, but with no hearing loss. Benign paroxysmal positional vertigo is triggered by changes in head position and lasts for only a few seconds. Meniere’s disease, meanwhile, is associated with hearing loss, tinnitus, and a feeling of fullness or pressure in the ears. Elderly patients with vertigo may be experiencing vertebrobasilar ischaemia, which is accompanied by dizziness upon neck extension. Acoustic neuroma, which is associated with hearing loss, vertigo, and tinnitus, is also a possible cause of vertigo. Other causes include posterior circulation stroke, trauma, multiple sclerosis, and ototoxicity from medications like gentamicin.
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This question is part of the following fields:
- Respiratory System
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Question 55
Correct
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A 65-year-old patient presents at the lung cancer clinic for their initial assessment. Their general practitioner referred them due to a persistent cough lasting 5 months and a weight loss of one stone in a month. The patient has quit smoking recently but used to smoke 20-30 cigarettes daily for 30 years. No asbestos exposure is reported.
A circular lesion was detected in the right upper lobe during a recent chest x-ray. A subsequent computed tomography (CT) scan indicated that this lung lesion is indicative of a primary lesion.
What is the most probable sub-type of lung cancer in this case?Your Answer: Adenocarcinoma
Explanation:Adenocarcinoma has become the most prevalent form of lung cancer, as per the given scenario. This type of cancer accounts for approximately one-third of all cases and can occur in both smokers and non-smokers. Therefore, the most probable answer to the question is adenocarcinoma. Mesothelioma, on the other hand, is a rare and incurable cancer that is almost exclusively linked to asbestos exposure and affects the pleura. It would not present as an upper lobe mass, but rather as a loss of lung volume or pleural opacity. Alveolar cell carcinoma, which is less common than adenocarcinoma, would likely cause significant sputum production.
Lung cancer can be classified into two main types: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). SCLC is less common, accounting for only 15% of cases, but has a worse prognosis. NSCLC, on the other hand, is more prevalent and can be further broken down into different subtypes. Adenocarcinoma is now the most common type of lung cancer, likely due to the increased use of low-tar cigarettes. It is often seen in non-smokers and accounts for 62% of cases in ‘never’ smokers. Squamous cell carcinoma is another subtype, and cavitating lesions are more common in this type of lung cancer. Large cell carcinoma, alveolar cell carcinoma, bronchial adenoma, and carcinoid are other subtypes of NSCLC. Differentiating between these subtypes is crucial as different drugs are available to treat each subtype.
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This question is part of the following fields:
- Respiratory System
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Question 56
Correct
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A 20-year-old woman comes to your general practice complaining of hearing difficulties for the past month. She was previously diagnosed with tinnitus by one of your colleagues at the practice 11 months ago. The patient reports that she can hear better when outside but struggles in quiet environments. Upon otoscopy, no abnormalities are found. Otosclerosis is one of the differential diagnoses for this patient, which primarily affects the ossicle that connects to the cochlea. What is the name of the ossicle that attaches to the cochlea at the oval window?
Your Answer: Stapes
Explanation:The stapes bone is the correct answer.
The ossicles are three bones located in the middle ear. They are arranged from lateral to medial and include the malleus, incus, and stapes. The malleus is the most lateral bone and its handle and lateral process attach to the tympanic membrane, making it visible on otoscopy. The head of the malleus articulates with the incus. The stapes bone is the most medial of the ossicles and is also known as the stirrup.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 57
Incorrect
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Which one of the following is not a typical feature of central chemoreceptors in the regulation of respiration?
Your Answer: During acute hypercapnia the carotid receptors will be stimulated first
Correct Answer: They are stimulated primarily by venous hypercapnia
Explanation:Arterial carbon dioxide stimulates them, but it takes longer to reach equilibrium compared to the carotid peripheral chemoreceptors. They are not as responsive to acidity because of the blood-brain barrier.
The Control of Ventilation in the Human Body
The control of ventilation in the human body is a complex process that involves various components working together to regulate the respiratory rate and depth of respiration. The respiratory centres, chemoreceptors, lung receptors, and muscles all play a role in this process. The automatic, involuntary control of respiration occurs from the medulla, which is responsible for controlling the respiratory rate and depth of respiration.
The respiratory centres consist of the medullary respiratory centre, apneustic centre, and pneumotaxic centre. The medullary respiratory centre has two groups of neurons, the ventral group, which controls forced voluntary expiration, and the dorsal group, which controls inspiration. The apneustic centre, located in the lower pons, stimulates inspiration and activates and prolongs inhalation. The pneumotaxic centre, located in the upper pons, inhibits inspiration at a certain point and fine-tunes the respiratory rate.
Ventilatory variables, such as the levels of pCO2, are the most important factors in ventilation control, while levels of O2 are less important. Peripheral chemoreceptors, located in the bifurcation of carotid arteries and arch of the aorta, respond to changes in reduced pO2, increased H+, and increased pCO2 in arterial blood. Central chemoreceptors, located in the medulla, respond to increased H+ in brain interstitial fluid to increase ventilation. It is important to note that the central receptors are not influenced by O2 levels.
Lung receptors also play a role in the control of ventilation. Stretch receptors respond to lung stretching, causing a reduced respiratory rate, while irritant receptors respond to smoke, causing bronchospasm. J (juxtacapillary) receptors are also involved in the control of ventilation. Overall, the control of ventilation is a complex process that involves various components working together to regulate the respiratory rate and depth of respiration.
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This question is part of the following fields:
- Respiratory System
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Question 58
Incorrect
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A 67-year-old woman presents to the clinic with a gradual onset of dyspnea on exertion over the past 6 months. She has a medical history of severe COPD and is currently receiving long-term oxygen therapy. During the examination, you observe pitting edema up to the mid-thighs, an elevated JVP with a prominent V wave, a precordial heave, and a loud P2. What is the most probable mechanism involved in this diagnosis?
Your Answer: Pulmonary arteries vasoconstriction due to hypercapnia
Correct Answer: Pulmonary arteries vasoconstriction due to hypoxia
Explanation:Hypoxia causes vasoconstriction of pulmonary arteries, leading to a diagnosis of right heart failure secondary to hypoxic lung disease, also known as cor pulmonale.
The Effects of Hypoxia on Pulmonary Arteries
When the partial pressure of oxygen in the blood decreases, the pulmonary arteries undergo vasoconstriction. This means that the blood vessels narrow, allowing blood to be redirected to areas of the lung that are better aerated. This response is a natural mechanism that helps to improve the efficiency of gaseous exchange in the lungs. By diverting blood to areas with more oxygen, the body can ensure that the tissues receive the oxygen they need to function properly. Overall, hypoxia triggers a physiological response that helps to maintain homeostasis in the body.
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This question is part of the following fields:
- Respiratory System
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Question 59
Correct
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During a schoolyard brawl a boy is hit in the chest. The stick passes through the posterior mediastinum (from left to right). Which one of the following structures is least likely to be injured?
Your Answer: Arch of the azygos vein
Explanation:The azygos vein’s arch is located within the middle mediastinum.
The mediastinum is the area located between the two pulmonary cavities and is covered by the mediastinal pleura. It extends from the thoracic inlet at the top to the diaphragm at the bottom. The mediastinum is divided into four regions: the superior mediastinum, middle mediastinum, posterior mediastinum, and anterior mediastinum.
The superior mediastinum is the area between the manubriosternal angle and T4/5. It contains important structures such as the superior vena cava, brachiocephalic veins, arch of aorta, thoracic duct, trachea, oesophagus, thymus, vagus nerve, left recurrent laryngeal nerve, and phrenic nerve. The anterior mediastinum contains thymic remnants, lymph nodes, and fat. The middle mediastinum contains the pericardium, heart, aortic root, arch of azygos vein, and main bronchi. The posterior mediastinum contains the oesophagus, thoracic aorta, azygos vein, thoracic duct, vagus nerve, sympathetic nerve trunks, and splanchnic nerves.
In summary, the mediastinum is a crucial area in the thorax that contains many important structures and is divided into four regions. Each region contains different structures that are essential for the proper functioning of the body.
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This question is part of the following fields:
- Respiratory System
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Question 60
Incorrect
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What causes a cervical rib?
Your Answer: Fusion of the transverse processes of the 6th and 7th cervical vertebrae
Correct Answer: Elongation of the transverse processes of the 7th cervical vertebrae
Explanation:Cervical ribs are formed when the transverse process of the 7th cervical vertebrae becomes elongated, resulting in a fibrous band that connects to the first thoracic rib.
Cervical ribs are a rare anomaly that affects only 0.2-0.4% of the population. They are often associated with neurological symptoms and are caused by an anomalous fibrous band that originates from the seventh cervical vertebrae and may arc towards the sternum. While most cases are congenital and present around the third decade of life, some cases have been reported to occur following trauma. Bilateral cervical ribs are present in up to 70% of cases. Compression of the subclavian artery can lead to absent radial pulse and a positive Adsons test, which involves lateral flexion of the neck towards the symptomatic side and traction of the symptomatic arm. Treatment is usually only necessary when there is evidence of neurovascular compromise, and the traditional operative method for excision is a transaxillary approach.
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This question is part of the following fields:
- Respiratory System
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Question 61
Incorrect
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A 53-year-old man arrives at the Emergency Department with jaundice and a distended abdomen. He has a history of alcoholism and has been hospitalized before for acute alcohol withdrawal. During the examination, you observe spider naevi on his upper chest wall and detect a shifting dullness on abdominal percussion, indicating ascites. Further imaging and investigation reveal portal vein hypertension and cirrhosis.
Where does this vessel start?Your Answer: L3
Correct Answer: L1
Explanation:Portal hypertension is commonly caused by liver cirrhosis, often due to alcohol abuse. The causes of this condition can be categorized as pre-hepatic, hepatic, or post-hepatic, depending on the location of the underlying pathology. The primary factors contributing to portal hypertension are increased vascular resistance in the portal venous system and elevated blood flow in the portal veins. The portal vein originates at the transpyloric plane, which is situated at the level of the body of L1. Other significant structures found at this location include the neck of the pancreas, the spleen, the duodenojejunal flexure, and the superior mesenteric artery.
The Transpyloric Plane and its Anatomical Landmarks
The transpyloric plane is an imaginary horizontal line that passes through the body of the first lumbar vertebrae (L1) and the pylorus of the stomach. It is an important anatomical landmark used in clinical practice to locate various organs and structures in the abdomen.
Some of the structures that lie on the transpyloric plane include the left and right kidney hilum (with the left one being at the same level as L1), the fundus of the gallbladder, the neck of the pancreas, the duodenojejunal flexure, the superior mesenteric artery, and the portal vein. The left and right colic flexure, the root of the transverse mesocolon, and the second part of the duodenum also lie on this plane.
In addition, the upper part of the conus medullaris (the tapered end of the spinal cord) and the spleen are also located on the transpyloric plane. Knowing the location of these structures is important for various medical procedures, such as abdominal surgeries and diagnostic imaging.
Overall, the transpyloric plane serves as a useful reference point for clinicians to locate important anatomical structures in the abdomen.
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This question is part of the following fields:
- Respiratory System
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Question 62
Incorrect
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A 50-year-old woman presents to your GP clinic with a complaint of a malodorous discharge from her left ear for the last 2 weeks. She also reports experiencing some hearing loss in her left ear and suspects it may be due to earwax. However, upon examination, there is no earwax present but instead a crust on the lower portion of the tympanic membrane. What is the probable diagnosis?
Your Answer: Otitis media
Correct Answer: Cholesteatoma
Explanation:When a patient presents with unilateral foul smelling discharge and deafness, it is important to consider the possibility of a cholesteatoma. If this is suspected during examination, it is necessary to refer the patient to an ENT specialist.
Pain is a common symptom of otitis media, while otitis externa typically causes inflammation and swelling of the ear canal. Impacted wax can lead to deafness, but it is unlikely to cause a discharge with a foul odor. It is also improbable for a woman of 45 years to have a foreign object in her ear for three weeks.
Understanding Cholesteatoma
Cholesteatoma is a benign growth of squamous epithelium that can cause damage to the skull base. It is most commonly found in individuals between the ages of 10 and 20 years old. Those born with a cleft palate are at a higher risk of developing cholesteatoma, with a 100-fold increase in risk.
The main symptoms of cholesteatoma include a persistent discharge with a foul odor and hearing loss. Other symptoms may occur depending on the extent of the growth, such as vertigo, facial nerve palsy, and cerebellopontine angle syndrome.
During otoscopy, a characteristic attic crust may be seen in the uppermost part of the eardrum.
Management of cholesteatoma involves referral to an ear, nose, and throat specialist for surgical removal. Early detection and treatment are important to prevent further damage to the skull base and surrounding structures.
In summary, cholesteatoma is a non-cancerous growth that can cause significant damage if left untreated. It is important to be aware of the symptoms and seek medical attention promptly if they occur.
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This question is part of the following fields:
- Respiratory System
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Question 63
Incorrect
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Which one of the following does not cause a normal anion gap acidosis?
Your Answer: Pancreatic fistula
Correct Answer: Uraemia
Explanation:Normal Gap Acidosis can be remembered using the acronym HARDUP, which stands for Hyperalimentation/hyperventilation, Acetazolamide, and R (which is currently blank).
Disorders of Acid-Base Balance
The acid-base nomogram is a useful tool for categorizing the various disorders of acid-base balance. Metabolic acidosis is the most common surgical acid-base disorder, characterized by a reduction in plasma bicarbonate levels. This can be caused by a gain of strong acid or loss of base, and is classified according to the anion gap. A normal anion gap indicates hyperchloraemic metabolic acidosis, which can be caused by gastrointestinal bicarbonate loss, renal tubular acidosis, drugs, or Addison’s disease. A raised anion gap indicates lactate, ketones, urate, or acid poisoning. Metabolic alkalosis, on the other hand, is usually caused by a rise in plasma bicarbonate levels due to a loss of hydrogen ions or a gain of bicarbonate. It is mainly caused by problems of the kidney or gastrointestinal tract. Respiratory acidosis is characterized by a rise in carbon dioxide levels due to alveolar hypoventilation, while respiratory alkalosis is caused by hyperventilation resulting in excess loss of carbon dioxide. These disorders have various causes, such as COPD, sedative drugs, anxiety, hypoxia, and pregnancy.
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This question is part of the following fields:
- Respiratory System
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Question 64
Correct
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A 55-year-old man from Hong Kong complains of fatigue, weight loss, and recurrent nosebleeds. During clinical examination, left-sided cervical lymphadenopathy is observed, and an ulcerated mass is found in the nasopharynx upon oropharyngeal examination. Which viral agent is typically associated with the development of this condition?
Your Answer: Epstein Barr virus
Explanation:Nasopharyngeal carcinoma is typically diagnosed through Trotter’s triad, which includes unilateral conductive hearing loss, ipsilateral facial and ear pain, and ipsilateral paralysis of the soft palate. This condition is commonly associated with previous Epstein Barr Virus infection, but there is no known link between the development of nasopharyngeal carcinoma and the other viruses mentioned.
Understanding Nasopharyngeal Carcinoma
Nasopharyngeal carcinoma is a type of squamous cell carcinoma that affects the nasopharynx. It is a rare form of cancer that is more common in individuals from Southern China and is associated with Epstein Barr virus infection. The presenting features of nasopharyngeal carcinoma include cervical lymphadenopathy, otalgia, unilateral serous otitis media, nasal obstruction, discharge, and/or epistaxis, and cranial nerve palsies such as III-VI.
To diagnose nasopharyngeal carcinoma, a combined CT and MRI scan is typically used. The first line of treatment for this type of cancer is radiotherapy. It is important to catch nasopharyngeal carcinoma early to increase the chances of successful treatment.
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This question is part of the following fields:
- Respiratory System
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Question 65
Incorrect
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A 26-year-old man has been experiencing a chronic cough and wheeze since starting a new job. He has noticed that his peak flow measurements are significantly reduced while at work but improve on the weekends. What substance is commonly linked to this type of asthma?
Your Answer: Cement dust
Correct Answer: Isocyanates
Explanation:Occupational Asthma: Causes and Symptoms
Occupational asthma is a type of asthma that is caused by exposure to certain chemicals in the workplace. Patients may experience worsening asthma symptoms while at work or notice an improvement in symptoms when away from work. The most common cause of occupational asthma is exposure to isocyanates, which are found in spray painting and foam moulding using adhesives. Other chemicals associated with occupational asthma include platinum salts, soldering flux resin, glutaraldehyde, flour, epoxy resins, and proteolytic enzymes.
To diagnose occupational asthma, it is recommended to measure peak expiratory flow at work and away from work. If there is a significant difference in peak expiratory flow, referral to a respiratory specialist is necessary. Treatment may include avoiding exposure to the triggering chemicals and using medications to manage asthma symptoms. It is important for employers to provide a safe working environment and for employees to report any concerns about potential exposure to harmful chemicals.
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This question is part of the following fields:
- Respiratory System
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Question 66
Incorrect
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A 14-year-old boy comes to the clinic complaining of ear pain. He mentions having some crusty discharge at the entrance of his ear canal when he woke up this morning. He denies any hearing loss, dizziness, or other symptoms. He swims twice a week. Upon examination, he has no fever. The auricle of his ear appears red, and pressing on the tragus causes discomfort. Otoscopy reveals an erythematous canal with a small amount of yellow discharge. The superior edge of the tympanic membrane is also red, but there is no bulging or fluid in the middle ear. Which bone articulates with the bone that is typically seen pressing against the tympanic membrane?
Your Answer: Malleus
Correct Answer: Incus
Explanation:The middle bone of the 3 ossicles is known as the incus. During otoscopy, the malleus can be observed in contact with the tympanic membrane and it connects with the incus medially.
The ossicles, which are the 3 bones in the middle ear, are arranged from lateral to medial as follows:
Malleus: This is the most lateral of the ossicles. The handle and lateral process of the malleus attach to the tympanic membrane, making it visible during otoscopy. The head of the malleus connects with the incus. The term ‘malleus’ is derived from the Latin word for ‘hammer’.
Incus: The incus is positioned between and connects with the other two ossicles. The body of the incus connects with the malleus, while the long limb of the bone connects with the stapes. The term ‘incus’ is derived from the Latin word for ‘anvil’.Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 67
Correct
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Sophie is a 15-year-old girl who has been brought to your GP clinic by her father. She has not yet started to develop breasts or have her first period. She does not seem worried, but her father is concerned. Sophie has a history of eczema and has been using topical steroids for several years. When her father leaves the room, she also admits to occasionally using tanning beds.
What could be a possible cause of delayed puberty in Sophie?Your Answer: Cystic fibrosis
Explanation:Delayed puberty can be caused by various factors, with constitutional delay being the most common cause. However, other causes must be ruled out before diagnosing constitutional delay. Some of these causes include chronic illnesses like kidney disease and Crohn’s disease, malnutrition from conditions such as anorexia nervosa, cystic fibrosis, and coeliac disease, excessive physical exercise, psychosocial deprivation, steroid therapy, hypothyroidism, tumours near the hypothalamo-pituitary axis, congenital anomalies like septo-optic dysplasia and congenital panhypopituitarism, irradiation treatment, and trauma such as surgery or head injury.
Understanding Cystic Fibrosis: Symptoms and Other Features
Cystic fibrosis is a genetic disorder that affects various organs in the body, particularly the lungs and digestive system. The symptoms of cystic fibrosis can vary from person to person, but some common presenting features include recurrent chest infections, malabsorption, and liver disease. In some cases, infants may experience meconium ileus or prolonged jaundice. It is important to note that while many patients are diagnosed during newborn screening or early childhood, some may not be diagnosed until adulthood.
Aside from the presenting features, there are other symptoms and features associated with cystic fibrosis. These include short stature, diabetes mellitus, delayed puberty, rectal prolapse, nasal polyps, and infertility. It is important for individuals with cystic fibrosis to receive proper medical care and management to address these symptoms and improve their quality of life.
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This question is part of the following fields:
- Respiratory System
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Question 68
Correct
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A 5-year-old boy comes to the clinic with his mother, complaining of ear pain that started last night. He has been unable to sleep due to the pain and has not been eating well. His mother reports that he seems different than his usual self. The affected side has muffled sounds, and he has a fever. Otoscopy reveals a bulging tympanic membrane with visible fluid-level. What is the structure that connects the middle ear to the nasopharynx?
Your Answer: Eustachian tube
Explanation:The pharyngotympanic tube, also known as the Eustachian tube, is responsible for connecting the middle ear and the nasopharynx, allowing for pressure equalization in the middle ear. It opens on the anterior wall of the middle ear and extends anteriorly, medially, and inferiorly to open into the nasopharynx. The palatovaginal canal connects the pterygopalatine fossa with the nasopharynx, while the pterygoid canal runs from the anterior boundary of the foramen lacerum to the pterygopalatine fossa. The semicircular canals are responsible for sensing balance, while the greater palatine canal transmits the greater and lesser palatine nerves, as well as the descending palatine artery and vein. In the case of ear pain, otitis media is a likely cause, which can be confirmed through otoscopy. The pharyngotympanic tube is particularly important in otitis media as it is the only outlet for pus or fluid in the middle ear, provided the tympanic membrane is intact.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 69
Incorrect
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A 65-year-old man visited his family doctor with a persistent cough that has been bothering him for the last six months. He complains of coughing up clear sputum and how it has been affecting his daily life. He has also noticed that he gets short of breath more easily and cannot keep up with his grandchildren. He has a medical history of well-controlled diabetes and dyslipidemia. He attended a smoking cessation program a few months ago, but he finds it challenging to quit smoking after smoking a pack of cigarettes a day for the past 40 years. During the examination, the doctor hears bilateral wheezing with some crackles. The doctor expresses concerns about a possible lung disease due to his long history of smoking and refers him for a pulmonary function test. What is likely to be found during the test?
Your Answer: The FEV1/FVC ratio is higher than normal as there is a larger decrease in FVC than FEV1
Correct Answer: The FEV1/FVC ratio is lower than normal as there is a larger decrease in FEV1 than FVC
Explanation:The patient’s prolonged smoking history and current symptoms suggest a diagnosis of chronic bronchitis and possibly emphysema, both of which are obstructive lung diseases. These conditions cause air to become trapped in the lungs, making it difficult to breathe out. Pulmonary function tests typically show a greater decrease in FEV1 than FVC in obstructive lung diseases, resulting in a lower FEV1/FVC ratio (also known as the Tiffeneau-Pinelli index). This is different from restrictive lung diseases, which may sometimes show an increase in the FEV1/FVC ratio due to a larger decrease in FVC than FEV1. Chest X-rays may reveal hyperinflated lungs in patients with obstructive lung diseases. An increase in FEV1 may occur in healthy individuals after exercise training or in patients with conditions like asthma after taking medication. Restrictive lung diseases, such as pneumoconioses, hypersensitivity pneumonitis, and idiopathic pulmonary fibrosis, are typically associated with a decrease in the FEV1/FVC ratio.
Understanding Pulmonary Function Tests
Pulmonary function tests are a useful tool in determining whether a respiratory disease is obstructive or restrictive. These tests measure various aspects of lung function, such as forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). By analyzing the results of these tests, doctors can diagnose and monitor conditions such as asthma, COPD, pulmonary fibrosis, and neuromuscular disorders.
In obstructive lung diseases, such as asthma and COPD, the FEV1 is significantly reduced, while the FVC may be reduced or normal. The FEV1% (FEV1/FVC) is also reduced. On the other hand, in restrictive lung diseases, such as pulmonary fibrosis and asbestosis, the FEV1 is reduced, but the FVC is significantly reduced. The FEV1% (FEV1/FVC) may be normal or increased.
It is important to note that there are many conditions that can affect lung function, and pulmonary function tests are just one tool in diagnosing and managing respiratory diseases. However, understanding the results of these tests can provide valuable information for both patients and healthcare providers.
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This question is part of the following fields:
- Respiratory System
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Question 70
Incorrect
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A 67-year-old man is admitted to the acute stroke unit following a haemorrhagic stroke. Three days after admission he complains of pain and swelling in the left calf. A Doppler ultrasound shows large DVT with extension into the upper leg. Given his recent stroke, anticoagulation is contraindicated, however, there is a significant risk of him developing a pulmonary embolus. The decision is made to insert an inferior vena cava (IVC) filter. The registrar inserting the filter is fairly junior, he plans to insert this just above the renal veins, however, asks the consultant if there are any landmarks he can use to guide him. The consultant advises him if he reaches the diaphragm he has gone too far!
At which vertebral level would the diaphragm be encountered when inserting an IVC filter?Your Answer: T12
Correct Answer: T8
Explanation:The point at which the inferior vena cava passes through the diaphragm is being asked in this question. The correct answer is T8, which is where the IVC crosses the diaphragm through the caval opening. The IVC is formed by the joining of the left and right common iliac veins at around L5.
In patients who are at high risk of pulmonary embolus and for whom anticoagulation is not effective or contraindicated, an IVC filter can be used. This filter is usually inserted above the renal veins, but it can be placed at any level, including the superior vena cava, if necessary.
The other options provided in the question, T6, T10, and T11, are not associated with any significant structures. The oesophagus passes through the diaphragm with the vagal trunk at T10.
Structures Perforating the Diaphragm
The diaphragm is a dome-shaped muscle that separates the thoracic and abdominal cavities. It plays a crucial role in breathing by contracting and relaxing to create negative pressure in the lungs. However, there are certain structures that perforate the diaphragm, allowing them to pass through from the thoracic to the abdominal cavity. These structures include the inferior vena cava at the level of T8, the esophagus and vagal trunk at T10, and the aorta, thoracic duct, and azygous vein at T12.
To remember these structures and their corresponding levels, a helpful mnemonic is I 8(ate) 10 EGGS AT 12. This means that the inferior vena cava is at T8, the esophagus and vagal trunk are at T10, and the aorta, thoracic duct, and azygous vein are at T12. Knowing these structures and their locations is important for medical professionals, as they may need to access or treat them during surgical procedures or diagnose issues related to them.
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This question is part of the following fields:
- Respiratory System
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Question 71
Incorrect
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A 29-year-old man comes to the clinic with a complaint of ear pain. He mentions that the pain started yesterday and has been preventing him from working. He also reports experiencing dizziness and muffled sounds on the affected side. During the examination, you notice that he has a fever and a bulging tympanic membrane with visible fluid. Based on these symptoms, you suspect that he has a middle ear infection. Now, you wonder which ossicle the tensor tympani muscle inserts into.
Which ossicle does the tensor tympani muscle insert into?Your Answer: Incus
Correct Answer: Malleus
Explanation:The tensor tympani muscle is located in a bony canal above the pharyngotympanic tube and originates from the cartilaginous portion of the tube, the bony canal, and the greater wing of the sphenoid bone. Its function is to reduce the magnitude of vibrations transmitted into the middle ear by pulling the handle of the malleus medially when contracted. This muscle is innervated by the nerve to tensor tympani, which arises from the mandibular nerve.
The middle ear contains three ossicles, which are the malleus, incus, and stapes. The malleus is the most lateral and attaches to the tympanic membrane, while the incus lies between and articulates with the other two ossicles. The stapes is the most medial and is connected to the oval window of the cochlea. The stapedius muscle is associated with the stapes. The lunate and trapezium are not bones of the middle ear but are carpal bones.
A patient with ear pain, difficulty hearing, dizziness, and fever may have otitis media, which is confirmed on otoscopy by a bulging tympanic membrane and visible fluid level.
Anatomy of the Ear
The ear is divided into three distinct regions: the external ear, middle ear, and internal ear. The external ear consists of the auricle and external auditory meatus, which are innervated by the greater auricular nerve and auriculotemporal branch of the trigeminal nerve. The middle ear is the space between the tympanic membrane and cochlea, and is connected to the nasopharynx by the eustachian tube. The tympanic membrane is composed of three layers and is approximately 1 cm in diameter. The middle ear is innervated by the glossopharyngeal nerve. The ossicles, consisting of the malleus, incus, and stapes, transmit sound vibrations from the tympanic membrane to the inner ear. The internal ear contains the cochlea, which houses the organ of corti, the sense organ of hearing. The vestibule accommodates the utricule and saccule, which contain endolymph and are surrounded by perilymph. The semicircular canals, which share a common opening into the vestibule, lie at various angles to the petrous temporal bone.
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This question is part of the following fields:
- Respiratory System
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Question 72
Incorrect
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A 10-year-old girl has been diagnosed with asthma. Her father asks you about the cause of her symptoms. What is the best response?
Inflammation of the lining of the bronchioles causes obstruction of the flow of air out from the lungs. This inflammation is reversible so symptoms of asthma may be intermittent. There may also be increased mucus production and bronchial muscle constriction.Your Answer: Chronic inflammation of the lining of the small airways causing them to become narrower
Correct Answer: Reversible inflammation of the lining of the small airways causing them to become narrower
Explanation:The bronchioles’ lining inflammation obstructs the outflow of air from the lungs, leading to asthma symptoms that may come and go. Additionally, there could be heightened mucus production and constriction of bronchial muscles.
Asthma is a common respiratory disorder that affects both children and adults. It is characterized by chronic inflammation of the airways, resulting in reversible bronchospasm and airway obstruction. While asthma can develop at any age, it typically presents in childhood and may improve or resolve with age. However, it can also persist into adulthood and cause significant morbidity, with around 1,000 deaths per year in the UK.
Several risk factors can increase the likelihood of developing asthma, including a personal or family history of atopy, antenatal factors such as maternal smoking or viral infections, low birth weight, not being breastfed, exposure to allergens and air pollution, and the hygiene hypothesis. Patients with asthma may also suffer from other atopic conditions such as eczema and hay fever, and some may be sensitive to aspirin. Occupational asthma is also a concern for those exposed to allergens in the workplace.
Symptoms of asthma include coughing, dyspnea, wheezing, and chest tightness, with coughing often worse at night. Signs may include expiratory wheezing on auscultation and reduced peak expiratory flow rate. Diagnosis is typically made through spirometry, which measures the volume and speed of air during exhalation and inhalation.
Management of asthma typically involves the use of inhalers to deliver drug therapy directly to the airways. Short-acting beta-agonists such as salbutamol are the first-line treatment for relieving symptoms, while inhaled corticosteroids like beclometasone dipropionate and fluticasone propionate are used for daily maintenance therapy. Long-acting beta-agonists like salmeterol and leukotriene receptor antagonists like montelukast may also be used in combination with other medications. Maintenance and reliever therapy (MART) is a newer approach that combines ICS and a fast-acting LABA in a single inhaler for both daily maintenance and symptom relief. Recent guidelines recommend offering a leukotriene receptor antagonist instead of a LABA for patients on SABA + ICS whose asthma is not well controlled, and considering MART for those with poorly controlled asthma.
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This question is part of the following fields:
- Respiratory System
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Question 73
Correct
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A 29-year-old pregnant woman is admitted to the hospital and delivers a baby girl at 32 weeks gestation. The newborn displays signs of distress including tachypnoea, tachycardia, expiratory grunting, nasal flaring, and chest wall recession.
What is the cell type responsible for producing the substance that the baby is lacking?Your Answer: Type 2 pneumocytes
Explanation:Types of Pneumocytes and Their Functions
Pneumocytes are specialized cells found in the lungs that play a crucial role in gas exchange. There are two main types of pneumocytes: type 1 and type 2. Type 1 pneumocytes are very thin squamous cells that cover around 97% of the alveolar surface. On the other hand, type 2 pneumocytes are cuboidal cells that secrete surfactant, a substance that reduces surface tension in the alveoli and prevents their collapse during expiration.
Type 2 pneumocytes start to develop around 24 weeks gestation, but adequate surfactant production does not take place until around 35 weeks. This is why premature babies are prone to respiratory distress syndrome. In addition, type 2 pneumocytes can differentiate into type 1 pneumocytes during lung damage, helping to repair and regenerate damaged lung tissue.
Apart from pneumocytes, there are also club cells (previously termed Clara cells) found in the bronchioles. These non-ciliated dome-shaped cells have a varied role, including protecting against the harmful effects of inhaled toxins and secreting glycosaminoglycans and lysozymes. Understanding the different types of pneumocytes and their functions is essential in comprehending the complex mechanisms involved in respiration.
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This question is part of the following fields:
- Respiratory System
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Question 74
Correct
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What is the carrier rate of cystic fibrosis in the United Kingdom?
Your Answer: 1 in 25
Explanation:Understanding Cystic Fibrosis
Cystic fibrosis is a genetic disorder that causes thickened secretions in the lungs and pancreas. It is an autosomal recessive condition that occurs due to a defect in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which regulates a chloride channel. In the UK, 80% of CF cases are caused by delta F508 on chromosome 7, and the carrier rate is approximately 1 in 25.
CF patients are at risk of colonization by certain organisms, including Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia (previously known as Pseudomonas cepacia), and Aspergillus. These organisms can cause infections and exacerbate symptoms in CF patients. It is important for healthcare providers to monitor and manage these infections to prevent further complications.
Overall, understanding cystic fibrosis and its associated risks can help healthcare providers provide better care for patients with this condition.
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This question is part of the following fields:
- Respiratory System
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Question 75
Incorrect
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A 25-year-old patient is undergoing routine pulmonary function testing to assess her chronic condition. The results are compared to a standardised predicted value and presented in the table below:
FEV1 75% of predicted
FVC 70% of predicted
FEV1/FVC 105%
What is the probable condition that this patient is suffering from, which can account for the above findings?Your Answer: Asthma
Correct Answer: Neuromuscular disorder
Explanation:The patient’s pulmonary function tests indicate a restrictive pattern, as both FEV1 and FVC are reduced. This suggests a possible neuromuscular disorder, as all other options would result in an obstructive pattern on the tests. Asthma, bronchiectasis, and COPD are unlikely diagnoses for a 20-year-old and would not match the test results. Pneumonia may affect the patient’s ability to perform the tests, but it is typically an acute condition that requires immediate treatment with antibiotics.
Understanding Pulmonary Function Tests
Pulmonary function tests are a useful tool in determining whether a respiratory disease is obstructive or restrictive. These tests measure various aspects of lung function, such as forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). By analyzing the results of these tests, doctors can diagnose and monitor conditions such as asthma, COPD, pulmonary fibrosis, and neuromuscular disorders.
In obstructive lung diseases, such as asthma and COPD, the FEV1 is significantly reduced, while the FVC may be reduced or normal. The FEV1% (FEV1/FVC) is also reduced. On the other hand, in restrictive lung diseases, such as pulmonary fibrosis and asbestosis, the FEV1 is reduced, but the FVC is significantly reduced. The FEV1% (FEV1/FVC) may be normal or increased.
It is important to note that there are many conditions that can affect lung function, and pulmonary function tests are just one tool in diagnosing and managing respiratory diseases. However, understanding the results of these tests can provide valuable information for both patients and healthcare providers.
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This question is part of the following fields:
- Respiratory System
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Question 76
Incorrect
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A 75-year-old man presents to the Emergency Department with acute shortness of breath following a 4-day febrile illness. On initial assessment, his oxygen saturation is 70% on room air with a PaO2 of 4.2kpa on an arterial blood gas.
What would be the anticipated physiological response in this patient?Your Answer: Increased tidal volume with decreased respiratory rate
Correct Answer: Pulmonary artery vasoconstriction
Explanation:When faced with hypoxia, the pulmonary arteries undergo vasoconstriction, which redirects blood flow away from poorly oxygenated areas of the lungs and towards well-oxygenated regions. In cases where patients remain hypoxic despite optimal mechanical ventilation, inhaled nitric oxide can be used to induce pulmonary vasodilation and reverse this response.
The statement that increased tidal volume with decreased respiratory rate is a response to hypoxia is incorrect. While an increase in tidal volume may occur, it is typically accompanied by an increase in respiratory rate.
Pulmonary artery vasodilation is also incorrect. Hypoxia actually induces vasoconstriction in the pulmonary vasculature, as explained above.
Similarly, reduced tidal volume with increased respiratory rate is not a direct response to hypoxia. While respiratory rate may increase, tidal volumes typically increase in response to hypoxia.
In contrast to the pulmonary vessels, the systemic vasculature vasodilates in response to hypoxia.
The Effects of Hypoxia on Pulmonary Arteries
When the partial pressure of oxygen in the blood decreases, the pulmonary arteries undergo vasoconstriction. This means that the blood vessels narrow, allowing blood to be redirected to areas of the lung that are better aerated. This response is a natural mechanism that helps to improve the efficiency of gaseous exchange in the lungs. By diverting blood to areas with more oxygen, the body can ensure that the tissues receive the oxygen they need to function properly. Overall, hypoxia triggers a physiological response that helps to maintain homeostasis in the body.
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This question is part of the following fields:
- Respiratory System
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Question 77
Correct
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A 9-month-old girl is brought to the hospital due to recurrent episodes of breathing difficulties. She has been experiencing a gradual worsening of symptoms, including a wet cough and expiratory wheezing, for the past 4 days.
During the examination, her temperature is recorded at 38.2°C, and her respiratory rate is 60 breaths per minute. Oxygen saturation levels are at 92% on air. Chest examination reveals mild intercostal retractions, scattered crackles, and expiratory wheezing in both lungs.
What is the most probable causative agent responsible for the symptoms?Your Answer: Respiratory syncytial virus
Explanation:Bronchiolitis is commonly caused by respiratory syncytial virus, which accounts for the majority of cases of serious lower respiratory tract infections in children under one.
Understanding Bronchiolitis
Bronchiolitis is a condition that is characterized by inflammation of the bronchioles. It is a serious lower respiratory tract infection that is most common in children under the age of one year. The pathogen responsible for 75-80% of cases is respiratory syncytial virus (RSV), while other causes include mycoplasma and adenoviruses. Bronchiolitis is more serious in children with bronchopulmonary dysplasia, congenital heart disease, or cystic fibrosis.
The symptoms of bronchiolitis include coryzal symptoms, dry cough, increasing breathlessness, and wheezing. Fine inspiratory crackles may also be present. Children with bronchiolitis may experience feeding difficulties associated with increasing dyspnoea, which is often the reason for hospital admission.
Immediate referral to hospital is recommended if the child has apnoea, looks seriously unwell to a healthcare professional, has severe respiratory distress, central cyanosis, or persistent oxygen saturation of less than 92% when breathing air. Clinicians should consider referring to hospital if the child has a respiratory rate of over 60 breaths/minute, difficulty with breastfeeding or inadequate oral fluid intake, or clinical dehydration.
The investigation for bronchiolitis involves immunofluorescence of nasopharyngeal secretions, which may show RSV. Management of bronchiolitis is largely supportive, with humidified oxygen given via a head box if oxygen saturations are persistently < 92%. Nasogastric feeding may be needed if children cannot take enough fluid/feed by mouth, and suction is sometimes used for excessive upper airway secretions.
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This question is part of the following fields:
- Respiratory System
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Question 78
Correct
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A 9-month-old girl is brought to the emergency department by her mother due to difficulty in breathing. The mother reports that her daughter has been restless, with a runny nose, feeling warm and a dry cough for the past 4 days. However, the mother is now quite worried because her daughter has not eaten since last night and her breathing seems to have worsened throughout the morning.
During the examination, the infant has a respiratory rate of 70/min, heart rate of 155/min, oxygen saturation of 92% and a temperature of 37.9ºC. The infant shows signs of nasal flaring and subcostal recession while breathing. On auscultation, widespread wheezing is heard. The infant is admitted, treated with humidified oxygen via nasal cannula and discharged home after 2 days.
What is the probable causative agent of this infant's illness?Your Answer: Respiratory syncytial virus
Explanation:Bronchiolitis typically presents with symptoms such as coryza and increased breathing effort, leading to feeding difficulties in children under one year of age. The majority of cases of bronchiolitis are caused by respiratory syncytial virus, while adenovirus is a less frequent culprit. On the other hand, croup is most commonly caused by parainfluenza virus.
Understanding Bronchiolitis
Bronchiolitis is a condition that is characterized by inflammation of the bronchioles. It is a serious lower respiratory tract infection that is most common in children under the age of one year. The pathogen responsible for 75-80% of cases is respiratory syncytial virus (RSV), while other causes include mycoplasma and adenoviruses. Bronchiolitis is more serious in children with bronchopulmonary dysplasia, congenital heart disease, or cystic fibrosis.
The symptoms of bronchiolitis include coryzal symptoms, dry cough, increasing breathlessness, and wheezing. Fine inspiratory crackles may also be present. Children with bronchiolitis may experience feeding difficulties associated with increasing dyspnoea, which is often the reason for hospital admission.
Immediate referral to hospital is recommended if the child has apnoea, looks seriously unwell to a healthcare professional, has severe respiratory distress, central cyanosis, or persistent oxygen saturation of less than 92% when breathing air. Clinicians should consider referring to hospital if the child has a respiratory rate of over 60 breaths/minute, difficulty with breastfeeding or inadequate oral fluid intake, or clinical dehydration.
The investigation for bronchiolitis involves immunofluorescence of nasopharyngeal secretions, which may show RSV. Management of bronchiolitis is largely supportive, with humidified oxygen given via a head box if oxygen saturations are persistently < 92%. Nasogastric feeding may be needed if children cannot take enough fluid/feed by mouth, and suction is sometimes used for excessive upper airway secretions.
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This question is part of the following fields:
- Respiratory System
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Question 79
Incorrect
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A 15-year-old boy presents to his GP with a painless swelling in his neck. The mass is located centrally just below the hyoid bone and does not cause any difficulty in swallowing or breathing. Upon examination, the GP notes that the mass moves with protrusion of the tongue and with swallowing. The GP diagnoses the boy with a benign thyroglossal cyst, which is caused by a persistent thyroglossal duct, and advises surgical removal. Where is the thyroglossal duct attached to the tongue?
Your Answer: Terminal sulcus of the tongue
Correct Answer: Foramen cecum
Explanation:The thyroglossal duct connects the thyroid gland to the tongue via the foramen caecum during embryonic development. The terminal sulcus, median sulcus, palatoglossal arch, and epiglottis are not connected to the thyroid gland.
Understanding Thyroglossal Cysts
Thyroglossal cysts are named after the thyroid and tongue, which are the two structures involved in their development. During embryology, the thyroid gland develops from the floor of the pharynx and descends into the neck, connected to the tongue by the thyroglossal duct. The foramen cecum is the point of attachment of the thyroglossal duct to the tongue. Normally, the thyroglossal duct atrophies, but in some people, it may persist and give rise to a thyroglossal duct cyst.
Thyroglossal cysts are more common in patients under 20 years old and are usually midline, between the isthmus of the thyroid and the hyoid bone. They move upwards with protrusion of the tongue and may be painful if infected. Understanding the embryology and presentation of thyroglossal cysts is important for proper diagnosis and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 80
Correct
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A 38-year-old man has been admitted to the ICU through the ED with reduced consciousness and cyanosis. Despite an oxygen saturation of 94% in the ED, both peripheral and central cyanosis were present. Arterial blood gas monitoring revealed significant hypoxia, but no evidence of methaemoglobin. The suspected diagnosis is carbon monoxide poisoning, and the patient is intubated and ventilated to prevent further leftward shift of the oxygen dissociation curve. What factors can cause this shift in the oxygen dissociation curve?
Your Answer: Hypocapnia
Explanation:The oxygen dissociation curve can be shifted to the left by low pCO2, which increases haemoglobin’s affinity for oxygen and makes it less likely to release oxygen to the tissues. In contrast, acidosis, hypercapnia, and hyperthermia cause a right shift of the curve, making it easier for oxygen to be released to the tissues. Raised levels of 2,3-diphosphoglycerate also shift the curve to the right by inhibiting oxygen binding to haemoglobin.
Understanding the Oxygen Dissociation Curve
The oxygen dissociation curve is a graphical representation of the relationship between the percentage of saturated haemoglobin and the partial pressure of oxygen in the blood. It is not influenced by the concentration of haemoglobin. The curve can shift to the left or right, indicating changes in oxygen delivery to tissues. When the curve shifts to the left, there is increased saturation of haemoglobin with oxygen, resulting in decreased oxygen delivery to tissues. Conversely, when the curve shifts to the right, there is reduced saturation of haemoglobin with oxygen, leading to enhanced oxygen delivery to tissues.
The L rule is a helpful mnemonic to remember the factors that cause a shift to the left, resulting in lower oxygen delivery. These factors include low levels of hydrogen ions (alkali), low partial pressure of carbon dioxide, low levels of 2,3-diphosphoglycerate, and low temperature. On the other hand, the mnemonic ‘CADET, face Right!’ can be used to remember the factors that cause a shift to the right, leading to raised oxygen delivery. These factors include carbon dioxide, acid, 2,3-diphosphoglycerate, exercise, and temperature.
Understanding the oxygen dissociation curve is crucial in assessing the oxygen-carrying capacity of the blood and the delivery of oxygen to tissues. By knowing the factors that can shift the curve to the left or right, healthcare professionals can make informed decisions in managing patients with respiratory and cardiovascular diseases.
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This question is part of the following fields:
- Respiratory System
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Question 81
Incorrect
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A 60-year-old man visits his GP with worries about his hearing in recent months. He has difficulty understanding conversations in noisy environments and his spouse has commented on his need for the television to be turned up to maximum volume.
During the examination, the GP conducts some basic tests and finds:
Rinne's Test - Air conduction > bone conduction in both ears
Weber's Test - Lateralises to the left ear
What can be inferred from these test results?Your Answer: Bilateral conductive hearing loss
Correct Answer: Left sensorineural hearing loss
Explanation:The patient has left sensorineural hearing loss, as indicated by the normal Rinne result (air conduction > bone conduction bilaterally) and abnormal Weber result (lateralising to the unaffected ear). In contrast, if the patient had conductive hearing loss, Rinne’s test would show bone conduction > air conduction, and Weber’s test would localise to the worse ear in bilateral conductive hearing loss or the affected ear in unilateral conductive hearing loss. For right sensorineural hearing loss, Rinne’s test would be normal, but Weber’s test would localise to the left ear.
Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness
Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.
Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.
The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.
Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 82
Incorrect
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Which one of the following would cause a rise in the carbon monoxide transfer factor (TLCO)?
Your Answer: Emphysema
Correct Answer: Pulmonary haemorrhage
Explanation:When alveolar haemorrhage takes place, the TLCO typically rises as a result of the increased absorption of carbon monoxide by haemoglobin within the alveoli.
Understanding Transfer Factor in Lung Function Testing
The transfer factor is a measure of how quickly a gas diffuses from the alveoli into the bloodstream. This is typically tested using carbon monoxide, and the results can be given as either the total gas transfer (TLCO) or the transfer coefficient corrected for lung volume (KCO). A raised TLCO may be caused by conditions such as asthma, pulmonary haemorrhage, left-to-right cardiac shunts, polycythaemia, hyperkinetic states, male gender, or exercise. On the other hand, a lower TLCO may be indicative of pulmonary fibrosis, pneumonia, pulmonary emboli, pulmonary oedema, emphysema, anaemia, or low cardiac output.
KCO tends to increase with age, and certain conditions may cause an increased KCO with a normal or reduced TLCO. These conditions include pneumonectomy/lobectomy, scoliosis/kyphosis, neuromuscular weakness, and ankylosis of costovertebral joints (such as in ankylosing spondylitis). Understanding transfer factor is important in lung function testing, as it can provide valuable information about a patient’s respiratory health and help guide treatment decisions.
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This question is part of the following fields:
- Respiratory System
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Question 83
Incorrect
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A 20-year-old female presented to the hospital with a complaint of a sore throat. She reported having a high-grade fever and severe pain on the right side of her throat for the past four days. The patient also experienced difficulty in swallowing and had restricted mouth opening. Additionally, she complained of bilateral ear pain and headache. Despite receiving oral antibiotics, her symptoms had worsened.
Upon examination, the patient had a fever of 38.5ºC and prominent cervical lymphadenopathy. Swelling of the right soft palate was observed, and the uvula was deviated to the left.
What is the most probable diagnosis?Your Answer: Retropharyngeal abscess
Correct Answer: Peritonsillar abscess (quinsy)
Explanation:Trismus, which is difficulty in opening the mouth, is a common symptom of peritonsillar abscess (also known as quinsy). It is important to note that quinsy is a complication of tonsillitis, not acute tonsillitis itself. Epiglottitis may present with muffled voice, drooling, and difficulty in breathing, while infectious mononucleosis is associated with other symptoms such as weight loss, fatigue, and enlarged lymph nodes and organs.
Peritonsillar Abscess: Symptoms and Treatment
A peritonsillar abscess, also known as quinsy, is a complication that can arise from bacterial tonsillitis. This condition is characterized by severe throat pain that is localized to one side, along with difficulty opening the mouth and reduced neck mobility. Additionally, the uvula may be deviated to the unaffected side. It is important to seek urgent medical attention from an ENT specialist if these symptoms are present.
The treatment for a peritonsillar abscess typically involves needle aspiration or incision and drainage, along with intravenous antibiotics. In some cases, a tonsillectomy may be recommended to prevent recurrence of the abscess. It is important to follow the recommended treatment plan and attend all follow-up appointments to ensure proper healing and prevent complications.
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This question is part of the following fields:
- Respiratory System
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Question 84
Incorrect
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A 55-year-old man presents to his GP complaining of vertigo, describing a sensation of the room spinning around him. He reports that the symptoms are exacerbated when he rolls over in bed. The GP suspects that otoliths in the semicircular canals of the inner ear may be the cause. What diagnostic test could the GP perform to confirm this suspicion?
Your Answer: Trendelenburg's test
Correct Answer: Dix-Hallpike manoeuvre
Explanation:Benign paroxysmal positional vertigo (BPPV) is suspected based on the patient’s history. To confirm the diagnosis, the Dix-Hallpike manoeuvre can be performed, which involves quickly moving the patient from a sitting to supine position and observing for nystagmus.
If BPPV is confirmed, the Epley manoeuvre can be used for treatment. This manoeuvre aims to dislodge otoliths by promoting fluid movement in the inner ear’s semicircular canals.
Carpal tunnel syndrome can be diagnosed by a positive Tinel’s sign. This involves tapping the median nerve over the flexor retinaculum, causing paraesthesia in the median nerve’s distribution.
The Trendelenburg test is used to assess venous valve competency in patients with varicose veins.
Benign paroxysmal positional vertigo (BPPV) is a common cause of vertigo that occurs suddenly when there is a change in head position. It is more prevalent in individuals over the age of 55 and is less common in younger patients. Symptoms of BPPV include dizziness and vertigo, which can be accompanied by nausea. Each episode typically lasts for 10-20 seconds and can be triggered by rolling over in bed or looking upwards. A positive Dix-Hallpike manoeuvre, which is indicated by vertigo and rotatory nystagmus, can confirm the diagnosis of BPPV.
Fortunately, BPPV has a good prognosis and usually resolves on its own within a few weeks to months. Treatment options include the Epley manoeuvre, which is successful in around 80% of cases, and vestibular rehabilitation exercises such as the Brandt-Daroff exercises. While medication such as Betahistine may be prescribed, it tends to have limited effectiveness. However, it is important to note that around half of individuals with BPPV may experience a recurrence of symptoms 3-5 years after their initial diagnosis.
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This question is part of the following fields:
- Respiratory System
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Question 85
Incorrect
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During a clinical trial examining oxygen consumption during exercise, participants aged 50 and above engage in high-intensity interval training exercises for 20 minutes while physiological measurements are recorded. What is the primary factor that is likely to restrict oxygen supply to tissues after the training session?
Your Answer: Myo-inositol trispyrophosphate (ITPP)
Correct Answer: Low pCO2
Explanation:When the pCO2 is low, the oxygen dissociation curve shifts to the left, which increases the affinity of haemoglobin for oxygen. This can limit the amount of oxygen available to tissues. On the other hand, high levels of pCO2 (hypercarbia) shift the curve to the right, decreasing the affinity of haemoglobin for oxygen and increasing oxygen availability to tissues.
In acidosis, the concentration of 2,3-diphosphoglycerate (DPG) increases, which binds to deoxyhaemoglobin and shifts the oxygen dissociation curve to the right. This results in increased oxygen release from the blood into tissues.
Hyperthermia also shifts the oxygen dissociation curve to the right, while the performance-enhancing substance myo-inositol trispyrophosphate (ITPP) has a similar effect.
Understanding the Oxygen Dissociation Curve
The oxygen dissociation curve is a graphical representation of the relationship between the percentage of saturated haemoglobin and the partial pressure of oxygen in the blood. It is not influenced by the concentration of haemoglobin. The curve can shift to the left or right, indicating changes in oxygen delivery to tissues. When the curve shifts to the left, there is increased saturation of haemoglobin with oxygen, resulting in decreased oxygen delivery to tissues. Conversely, when the curve shifts to the right, there is reduced saturation of haemoglobin with oxygen, leading to enhanced oxygen delivery to tissues.
The L rule is a helpful mnemonic to remember the factors that cause a shift to the left, resulting in lower oxygen delivery. These factors include low levels of hydrogen ions (alkali), low partial pressure of carbon dioxide, low levels of 2,3-diphosphoglycerate, and low temperature. On the other hand, the mnemonic ‘CADET, face Right!’ can be used to remember the factors that cause a shift to the right, leading to raised oxygen delivery. These factors include carbon dioxide, acid, 2,3-diphosphoglycerate, exercise, and temperature.
Understanding the oxygen dissociation curve is crucial in assessing the oxygen-carrying capacity of the blood and the delivery of oxygen to tissues. By knowing the factors that can shift the curve to the left or right, healthcare professionals can make informed decisions in managing patients with respiratory and cardiovascular diseases.
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This question is part of the following fields:
- Respiratory System
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Question 86
Correct
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A 32-year-old woman arrives at the emergency department complaining of sudden shortness of breath and a sharp pain on the right side of her chest that worsens with inspiration. Upon examination, the doctor observes hyper-resonance and reduced breath sounds on the right side of her chest.
What is a risk factor for this condition, considering the probable diagnosis?Your Answer: Cystic fibrosis
Explanation:Pneumothorax can be identified by reduced breath sounds and a hyper-resonant chest on the same side as the pain. Cystic fibrosis is a significant risk factor for pneumothorax due to the frequent chest infections, lung remodeling, and air trapping associated with the disease. While tall, male smokers are also at increased risk, Marfan’s syndrome, not Turner syndrome, is a known risk factor.
Pneumothorax: Characteristics and Risk Factors
Pneumothorax is a medical condition characterized by the presence of air in the pleural cavity, which is the space between the lungs and the chest wall. This condition can occur spontaneously or as a result of trauma or medical procedures. There are several risk factors associated with pneumothorax, including pre-existing lung diseases such as COPD, asthma, cystic fibrosis, lung cancer, and Pneumocystis pneumonia. Connective tissue diseases like Marfan’s syndrome and rheumatoid arthritis can also increase the risk of pneumothorax. Ventilation, including non-invasive ventilation, can also be a risk factor.
Symptoms of pneumothorax tend to come on suddenly and can include dyspnoea, chest pain (often pleuritic), sweating, tachypnoea, and tachycardia. In some cases, catamenial pneumothorax can be the cause of spontaneous pneumothoraces occurring in menstruating women. This type of pneumothorax is thought to be caused by endometriosis within the thorax. Early diagnosis and treatment of pneumothorax are crucial to prevent complications and improve outcomes.
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This question is part of the following fields:
- Respiratory System
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Question 87
Incorrect
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John, a 55-year-old man, arrives at the emergency department complaining of chest pain that is relieved by leaning forward. He also mentions that the pain spreads to his left shoulder. The diagnosis is pericarditis.
Which nerve is accountable for the referred pain in this case?Your Answer: Left pericardial nerve
Correct Answer: Phrenic nerve
Explanation:The phrenic nerve provides motor innervation to the diaphragm and sensory innervation to the pleura and pericardium. Pericarditis can cause referred pain to the shoulder due to the supraclavicular nerves originating at C3-4. It is important to note that there are no pericardial nerves. The spinal accessory nerve innervates the trapezius and sternocleidomastoid muscles, while the trochlear nerve supplies the superior oblique muscle. Although the vagus nerve has various functions, it does not supply the pericardium.
The Phrenic Nerve: Origin, Path, and Supplies
The phrenic nerve is a crucial nerve that originates from the cervical spinal nerves C3, C4, and C5. It supplies the diaphragm and provides sensation to the central diaphragm and pericardium. The nerve passes with the internal jugular vein across scalenus anterior and deep to the prevertebral fascia of the deep cervical fascia.
The right phrenic nerve runs anterior to the first part of the subclavian artery in the superior mediastinum and laterally to the superior vena cava. In the middle mediastinum, it is located to the right of the pericardium and passes over the right atrium to exit the diaphragm at T8. On the other hand, the left phrenic nerve passes lateral to the left subclavian artery, aortic arch, and left ventricle. It passes anterior to the root of the lung and pierces the diaphragm alone.
Understanding the origin, path, and supplies of the phrenic nerve is essential in diagnosing and treating conditions that affect the diaphragm and pericardium.
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This question is part of the following fields:
- Respiratory System
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Question 88
Incorrect
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A 49-year-old man experiences blunt force trauma to the head and subsequently experiences respiratory distress, leading to hypercapnia. What is the most probable consequence of this condition?
Your Answer: Cerebral blood flow will remain unchanged
Correct Answer: Cerebral vasodilation
Explanation:Cerebral vasodilation is a common result of hypercapnia, which can be problematic for patients with cranial trauma due to the potential increase in intracranial pressure.
Understanding the Monro-Kelly Doctrine and Autoregulation in the CNS
The Monro-Kelly doctrine governs the pressure within the cranium by considering the skull as a closed box. The loss of cerebrospinal fluid (CSF) can accommodate increases in mass until a critical point is reached, usually at 100-120ml of CSF lost. Beyond this point, intracranial pressure (ICP) rises sharply, and pressure will eventually equate with mean arterial pressure (MAP), leading to neuronal death and herniation.
The central nervous system (CNS) has the ability to autoregulate its own blood supply through vasoconstriction and dilation of cerebral blood vessels. However, extreme blood pressure levels can exceed this capacity, increasing the risk of stroke. Additionally, metabolic factors such as hypercapnia can cause vasodilation, which is crucial in ventilating head-injured patients.
It is important to note that the brain can only metabolize glucose, and a decrease in glucose levels can lead to impaired consciousness. Understanding the Monro-Kelly doctrine and autoregulation in the CNS is crucial in managing intracranial pressure and preventing neurological damage.
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This question is part of the following fields:
- Respiratory System
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Question 89
Correct
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A 3-year-old male toddler of Asian descent is referred to a paediatrician by his GP due to recurrent respiratory infections and failure to thrive. The doctor orders a sweat test, which comes back positive. What are the potential complications associated with the likely diagnosis?
Your Answer: Steatorrhea
Explanation:Cystic fibrosis can lead to steatorrhea, which is caused by the malabsorption of fat in the intestines. This is a common symptom of the disease and requires specialist management. While patients with CF may have a slightly increased risk of sensorineural hearing loss, this is mainly due to the side effects of certain drugs used to treat the disease. Melaena, which is the passage of dark faeces due to partially digested blood from the upper gastrointestinal system, is a rare symptom in patients with CF. There is no association between CF and intellectual disability. Although some studies suggest an increased incidence of pulmonary emboli in patients with CF, the associated risk is small and mainly due to the use of central venous catheters and liver dysfunction or vitamin K deficiency.
Understanding Cystic Fibrosis: Symptoms and Other Features
Cystic fibrosis is a genetic disorder that affects various organs in the body, particularly the lungs and digestive system. The symptoms of cystic fibrosis can vary from person to person, but some common presenting features include recurrent chest infections, malabsorption, and liver disease. In some cases, infants may experience meconium ileus or prolonged jaundice. It is important to note that while many patients are diagnosed during newborn screening or early childhood, some may not be diagnosed until adulthood.
Aside from the presenting features, there are other symptoms and features associated with cystic fibrosis. These include short stature, diabetes mellitus, delayed puberty, rectal prolapse, nasal polyps, and infertility. It is important for individuals with cystic fibrosis to receive proper medical care and management to address these symptoms and improve their quality of life.
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This question is part of the following fields:
- Respiratory System
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Question 90
Incorrect
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A man in his early fifties comes in with a painful rash caused by herpes on the external auditory meatus. He also has facial palsy on the same side, along with deafness, tinnitus, and vertigo. What is the probable diagnosis?
Your Answer: Bell's palsy
Correct Answer: Ramsay Hunt syndrome
Explanation:Ramsay Hunt syndrome is characterized by a combination of Bell’s palsy facial paralysis, along with symptoms such as a herpetic rash, deafness, tinnitus, and vertigo. It is important to note that the rash may not always be visible, despite being present.
While Bell’s palsy may present with facial paralysis, it does not typically involve the presence of herpetic rashes.
Understanding Ramsay Hunt Syndrome
Ramsay Hunt syndrome, also known as herpes zoster oticus, is a condition that occurs when the varicella zoster virus reactivates in the geniculate ganglion of the seventh cranial nerve. The first symptom of this syndrome is often auricular pain, followed by facial nerve palsy and a vesicular rash around the ear. Other symptoms may include vertigo and tinnitus.
To manage Ramsay Hunt syndrome, doctors typically prescribe oral acyclovir and corticosteroids. These medications can help reduce the severity of symptoms and prevent complications.
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This question is part of the following fields:
- Respiratory System
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Question 91
Correct
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A 25-year-old man comes to the doctor complaining of frequent urination, unquenchable thirst, and recent weight loss of around 5 kilograms in the last 2 months. The patient reports feeling extremely tired, although he acknowledges that work has been stressful lately, and his eating habits have been poor. The patient has a medical history of cystic fibrosis, with a Pseudomonas aeruginosa flare-up last year that required a brief hospital stay.
What could be the probable reason for this patient's clinical presentation?Your Answer: Diabetes mellitus
Explanation:Cystic fibrosis can lead to the development of a unique type of diabetes mellitus known as cystic fibrosis-related diabetes mellitus. This is caused by the destruction of pancreatic islets due to abnormal chloride channel function, which leads to thickened bodily secretions that damage the exocrine pancreas over time. As a result, there is a gradual reduction in islet cell function and relative insulin deficiency, which can cause symptoms such as polydipsia, polyuria, fatigue, and weight loss.
It is important to note that this type of diabetes is distinct from type 1 or type 2 diabetes. Additionally, it is not associated with other conditions such as diabetes insipidus, primary hyperparathyroidism, or prostatitis, which have their own unique symptoms and causes.
Understanding Cystic Fibrosis: Symptoms and Other Features
Cystic fibrosis is a genetic disorder that affects various organs in the body, particularly the lungs and digestive system. The symptoms of cystic fibrosis can vary from person to person, but some common presenting features include recurrent chest infections, malabsorption, and liver disease. In some cases, infants may experience meconium ileus or prolonged jaundice. It is important to note that while many patients are diagnosed during newborn screening or early childhood, some may not be diagnosed until adulthood.
Aside from the presenting features, there are other symptoms and features associated with cystic fibrosis. These include short stature, diabetes mellitus, delayed puberty, rectal prolapse, nasal polyps, and infertility. It is important for individuals with cystic fibrosis to receive proper medical care and management to address these symptoms and improve their quality of life.
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This question is part of the following fields:
- Respiratory System
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Question 92
Incorrect
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A 24-year-old man is admitted to the emergency department after a car accident. During the initial evaluation, he complains of difficulty breathing. A portable chest X-ray shows a 3 cm gap between the right lung margin and the chest wall, indicating a significant traumatic pneumothorax. The medical team administers high-flow oxygen and performs a right-sided chest drain insertion to drain the pneumothorax.
What is a potential negative outcome that could arise from the insertion of a chest drain?Your Answer: Pyothorax
Correct Answer: Winging of the scapula
Explanation:Insertion of a chest drain poses a risk of damaging the long thoracic nerve, which runs from the neck to the serratus anterior muscle. This can result in weakness or paralysis of the muscle, causing a winged scapula that is noticeable along the medial border of the scapula. It is important to use aseptic technique during the procedure to prevent hospital-acquired pleural infection. Chylothorax, pneumothorax, and pyothorax are all conditions that may require chest drain insertion, but they are not known complications of the procedure. Therefore, these options are not applicable.
Anatomy of Chest Drain Insertion
Chest drain insertion is necessary for various medical conditions such as trauma, haemothorax, pneumothorax, and pleural effusion. The size of the chest drain used depends on the specific condition being treated. While ultrasound guidance is an option, the anatomical method is typically tested in exams.
It is recommended that chest drains are placed in the safe triangle, which is located in the mid axillary line of the 5th intercostal space. This triangle is bordered by the anterior edge of the latissimus dorsi, the lateral border of pectoralis major, a line superior to the horizontal level of the nipple, and the apex below the axilla. Another triangle, known as the triangle of auscultation, is situated behind the scapula and is bounded by the trapezius, latissimus dorsi, and vertebral border of the scapula. By folding the arms across the chest and bending forward, parts of the sixth and seventh ribs and the interspace between them become subcutaneous and available for auscultation.
References:
– Prof Harold Ellis. The applied anatomy of chest drains insertions. British Journal of hospital medicine 2007; (68): 44-45.
– Laws D, Neville E, Duffy J. BTS guidelines for insertion of chest drains. Thorax, 2003; (58): 53-59. -
This question is part of the following fields:
- Respiratory System
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Question 93
Incorrect
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A 65-year-old man is undergoing an upper GI endoscopy due to difficulty swallowing. During the procedure, a suspicious-looking blockage is found at 33 cm from the incisors. The endoscopist tries to widen the area with a balloon, but the tumor causes a rupture in the oesophageal wall. Where will the contents of the oesophagus now drain?
Your Answer: Superior mediastinum
Correct Answer: Posterior mediastinum
Explanation:The oesophagus is expected to remain within the thoracic cavity and situated in the posterior mediastinum at this point.
The mediastinum is the area located between the two pulmonary cavities and is covered by the mediastinal pleura. It extends from the thoracic inlet at the top to the diaphragm at the bottom. The mediastinum is divided into four regions: the superior mediastinum, middle mediastinum, posterior mediastinum, and anterior mediastinum.
The superior mediastinum is the area between the manubriosternal angle and T4/5. It contains important structures such as the superior vena cava, brachiocephalic veins, arch of aorta, thoracic duct, trachea, oesophagus, thymus, vagus nerve, left recurrent laryngeal nerve, and phrenic nerve. The anterior mediastinum contains thymic remnants, lymph nodes, and fat. The middle mediastinum contains the pericardium, heart, aortic root, arch of azygos vein, and main bronchi. The posterior mediastinum contains the oesophagus, thoracic aorta, azygos vein, thoracic duct, vagus nerve, sympathetic nerve trunks, and splanchnic nerves.
In summary, the mediastinum is a crucial area in the thorax that contains many important structures and is divided into four regions. Each region contains different structures that are essential for the proper functioning of the body.
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This question is part of the following fields:
- Respiratory System
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Question 94
Incorrect
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A 24-year-old female arrives at the emergency department in a state of panic following a recent breakup with her partner. She complains of chest tightness and dizziness, fearing that she may be experiencing a heart attack. Upon examination, her vital signs are stable except for a respiratory rate of 34 breaths per minute. What compensatory mechanism is expected in response to the change in her oxyhaemoglobin dissociation curve, and what is the underlying cause?
Your Answer: Right shift, respiratory acidosis
Correct Answer: Left shift, respiratory alkalosis
Explanation:The patient’s oxygen dissociation curve has shifted to the left, indicating respiratory alkalosis. This is likely due to the patient experiencing a panic attack and hyperventilating, leading to a decrease in carbon dioxide levels and an increase in the affinity of haemoglobin for oxygen. Respiratory acidosis, hypercapnia, and a right shift of the curve are not appropriate explanations for this patient’s condition.
Understanding the Oxygen Dissociation Curve
The oxygen dissociation curve is a graphical representation of the relationship between the percentage of saturated haemoglobin and the partial pressure of oxygen in the blood. It is not influenced by the concentration of haemoglobin. The curve can shift to the left or right, indicating changes in oxygen delivery to tissues. When the curve shifts to the left, there is increased saturation of haemoglobin with oxygen, resulting in decreased oxygen delivery to tissues. Conversely, when the curve shifts to the right, there is reduced saturation of haemoglobin with oxygen, leading to enhanced oxygen delivery to tissues.
The L rule is a helpful mnemonic to remember the factors that cause a shift to the left, resulting in lower oxygen delivery. These factors include low levels of hydrogen ions (alkali), low partial pressure of carbon dioxide, low levels of 2,3-diphosphoglycerate, and low temperature. On the other hand, the mnemonic ‘CADET, face Right!’ can be used to remember the factors that cause a shift to the right, leading to raised oxygen delivery. These factors include carbon dioxide, acid, 2,3-diphosphoglycerate, exercise, and temperature.
Understanding the oxygen dissociation curve is crucial in assessing the oxygen-carrying capacity of the blood and the delivery of oxygen to tissues. By knowing the factors that can shift the curve to the left or right, healthcare professionals can make informed decisions in managing patients with respiratory and cardiovascular diseases.
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This question is part of the following fields:
- Respiratory System
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Question 95
Incorrect
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Which of the following nerve roots provide nerve fibers to the ansa cervicalis?
Your Answer: C2, C3 and C6
Correct Answer: C1, C2 and C3
Explanation:The ansa cervicalis muscles can be remembered using the acronym GHost THought SOmeone Stupid Shot Irene. These muscles include the GenioHyoid, ThyroidHyoid, Superior Omohyoid, SternoThyroid, SternoHyoid, and Inferior Omohyoid. The ansa cervicalis is made up of a superior and inferior root, which originate from C1, C2, and C3. The superior root begins where the nerve crosses the internal carotid artery and descends in the anterior triangle of the neck. The inferior root joins the superior root in the mid neck region and can pass either superficially or deep to the internal jugular vein.
The ansa cervicalis is a nerve that provides innervation to the sternohyoid, sternothyroid, and omohyoid muscles. It is composed of two roots: the superior root, which branches off from C1 and is located anterolateral to the carotid sheath, and the inferior root, which is derived from the C2 and C3 roots and passes posterolateral to the internal jugular vein. The inferior root enters the inferior aspect of the strap muscles, which are located in the neck, and should be divided in their upper half when exposing a large goitre. The ansa cervicalis is situated in front of the carotid sheath and is an important nerve for the proper functioning of the neck muscles.
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This question is part of the following fields:
- Respiratory System
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Question 96
Incorrect
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An 80-year-old man visits the GP clinic for a routine hearing examination. He reports a decline in hearing ability in his left ear for the past few months. After conducting Rinne and Weber tests, you determine that he has conductive hearing loss in the left ear. Upon otoscopy, you observe cerumen impaction.
What are the test findings for this patient?Your Answer: Rinne: air conduction > bone conduction in right ear; Weber: lateralising to left ear
Correct Answer: Rinne: bone conduction > air conduction in right ear; Weber: lateralising to right ear
Explanation:Rinne’s and Weber’s Test for Differentiating Conductive and Sensorineural Deafness
Rinne’s and Weber’s tests are used to differentiate between conductive and sensorineural deafness. Rinne’s test involves placing a tuning fork over the mastoid process until the sound is no longer heard, then repositioning it just over the external acoustic meatus. A positive test indicates that air conduction (AC) is better than bone conduction (BC), while a negative test indicates that BC is better than AC, suggesting conductive deafness.
Weber’s test involves placing a tuning fork in the middle of the forehead equidistant from the patient’s ears and asking the patient which side is loudest. In unilateral sensorineural deafness, sound is localized to the unaffected side, while in unilateral conductive deafness, sound is localized to the affected side.
The table below summarizes the interpretation of Rinne and Weber tests. A normal result indicates that AC is greater than BC bilaterally and the sound is midline. Conductive hearing loss is indicated by BC being greater than AC in the affected ear and AC being greater than BC in the unaffected ear, with the sound lateralizing to the affected ear. Sensorineural hearing loss is indicated by AC being greater than BC bilaterally, with the sound lateralizing to the unaffected ear.
Overall, Rinne’s and Weber’s tests are useful tools for differentiating between conductive and sensorineural deafness, allowing for appropriate management and treatment.
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This question is part of the following fields:
- Respiratory System
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Question 97
Correct
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An 87-year-old man with a history of interstitial lung disease is admitted with fever, productive cough, and difficulty breathing. His inflammatory markers are elevated, and a chest x-ray reveals focal patchy consolidation in the right lung. He requires oxygen supplementation as his oxygen saturation level is 87% on room air. What factor causes a decrease in haemoglobin's affinity for oxygen?
Your Answer: Increase in temperature
Explanation:What effect does pyrexia have on the oxygen dissociation curve?
Understanding the Oxygen Dissociation Curve
The oxygen dissociation curve is a graphical representation of the relationship between the percentage of saturated haemoglobin and the partial pressure of oxygen in the blood. It is not influenced by the concentration of haemoglobin. The curve can shift to the left or right, indicating changes in oxygen delivery to tissues. When the curve shifts to the left, there is increased saturation of haemoglobin with oxygen, resulting in decreased oxygen delivery to tissues. Conversely, when the curve shifts to the right, there is reduced saturation of haemoglobin with oxygen, leading to enhanced oxygen delivery to tissues.
The L rule is a helpful mnemonic to remember the factors that cause a shift to the left, resulting in lower oxygen delivery. These factors include low levels of hydrogen ions (alkali), low partial pressure of carbon dioxide, low levels of 2,3-diphosphoglycerate, and low temperature. On the other hand, the mnemonic ‘CADET, face Right!’ can be used to remember the factors that cause a shift to the right, leading to raised oxygen delivery. These factors include carbon dioxide, acid, 2,3-diphosphoglycerate, exercise, and temperature.
Understanding the oxygen dissociation curve is crucial in assessing the oxygen-carrying capacity of the blood and the delivery of oxygen to tissues. By knowing the factors that can shift the curve to the left or right, healthcare professionals can make informed decisions in managing patients with respiratory and cardiovascular diseases.
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This question is part of the following fields:
- Respiratory System
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Question 98
Incorrect
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A 65-year-old man is having a coronary artery bypass surgery. Which structure would typically need to be divided during the median sternotomy procedure?
Your Answer: Parietal pleura
Correct Answer: Interclavicular ligament
Explanation:During a median sternotomy, the interclavicular ligament is typically cut to allow access. However, it is important to avoid intentionally cutting the pleural reflections, as this can lead to the accumulation of fluid in the pleural cavity and require the insertion of a chest drain. The pectoralis major muscles may also be encountered, but if the incision is made in the midline, they should not need to be formally divided. It is crucial to be mindful of the proximity of the brachiocephalic vein and avoid injuring it, as this can result in significant bleeding.
Sternotomy Procedure
A sternotomy is a surgical procedure that involves making an incision in the sternum to access the heart and great vessels. The most common type of sternotomy is a median sternotomy, which involves making a midline incision from the interclavicular fossa to the xiphoid process. The fat and subcutaneous tissues are then divided to the level of the sternum, and the periosteum may be gently mobilized off the midline. However, it is important to avoid vigorous periosteal stripping. A bone saw is used to divide the bone itself, and bleeding from the bony edges of the cut sternum is stopped using roller ball diathermy or bone wax.
Posteriorly, the reflections of the parietal pleura should be identified and avoided, unless surgery to the lung is planned. The fibrous pericardium is then incised, and the heart is brought into view. It is important to avoid the left brachiocephalic vein, which is an important posterior relation at the superior aspect of the sternotomy incision. More inferiorly, the thymic remnants may be identified. At the inferior aspect of the incision, the abdominal cavity may be entered, although this is seldom troublesome.
Overall, a sternotomy is a complex surgical procedure that requires careful attention to detail and a thorough understanding of the anatomy of the chest and heart. By following the proper techniques and precautions, surgeons can safely access the heart and great vessels to perform a variety of life-saving procedures.
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This question is part of the following fields:
- Respiratory System
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Question 99
Incorrect
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An 80-year-old man with metastatic lung cancer arrives at the acute medical unit with sudden shortness of breath. A chest x-ray shows a malignant pleural effusion encasing the right lung. The medical registrar intends to perform a pleural tap to drain the effusion and send a sample to the lab. The registrar takes into account the effusion's position around the lung. What is the minimum level of the effusion in the mid-axillary line?
Your Answer: 9th rib
Correct Answer: 10th rib
Explanation:The parietal pleura can be found at the 10th rib in the mid-axillary line, while the visceral pleura is closely attached to the lung tissue and can be considered as one. The location of the parietal pleura is more inferior than that of the visceral pleura, with the former being at the 8th rib in the midclavicular line and the 10th rib in the midaxillary line. The location of the parietal pleura in the scapular line is not specified.
Anatomy of the Lungs
The lungs are a pair of organs located in the chest cavity that play a vital role in respiration. The right lung is composed of three lobes, while the left lung has two lobes. The apex of both lungs is approximately 4 cm superior to the sternocostal joint of the first rib. The base of the lungs is in contact with the diaphragm, while the costal surface corresponds to the cavity of the chest. The mediastinal surface contacts the mediastinal pleura and has the cardiac impression. The hilum is a triangular depression above and behind the concavity, where the structures that form the root of the lung enter and leave the viscus. The right main bronchus is shorter, wider, and more vertical than the left main bronchus. The inferior borders of both lungs are at the 6th rib in the mid clavicular line, 8th rib in the mid axillary line, and 10th rib posteriorly. The pleura runs two ribs lower than the corresponding lung level. The bronchopulmonary segments of the lungs are divided into ten segments, each with a specific function.
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This question is part of the following fields:
- Respiratory System
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Question 100
Incorrect
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A 72-year-old man with thyroid cancer is hospitalized for dyspnea. What is the most appropriate test to evaluate potential compression of the upper respiratory tract?
Your Answer: Peak expiratory flow rate
Correct Answer: Flow volume loop
Explanation:Understanding Flow Volume Loops
A flow volume loop is a graphical representation of the amount of air that a person can inhale and exhale over time. It is often described as a triangle on top of a semi-circle. This loop is useful in assessing the compression of the upper airway, which can be caused by various conditions such as asthma, chronic obstructive pulmonary disease (COPD), and sleep apnea.
To interpret a flow volume loop, the vertical axis represents the flow rate, while the horizontal axis represents the volume of air. The loop starts at the bottom left corner, where the person begins to inhale. As the person inhales, the flow rate increases, creating the upward slope of the triangle. At the top of the triangle, the person reaches their maximum inhalation volume.
The person then begins to exhale, creating the downward slope of the triangle. The flow rate decreases as the person exhales, until they reach their maximum exhalation volume, represented by the semi-circle. The loop then returns to the starting point, completing one full cycle.
Overall, flow volume loops are a valuable tool in diagnosing and monitoring respiratory conditions. By analyzing the shape and size of the loop, healthcare professionals can identify abnormalities in lung function and determine the appropriate treatment plan.
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This question is part of the following fields:
- Respiratory System
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