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Question 1
Incorrect
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A 48-year-old male presents for a preoperative evaluation for an inguinal hernia repair. During the assessment, you observe a loculated left pleural effusion on his chest x-ray. Upon further inquiry, the patient discloses that he worked as a builder three decades ago. What is the probable reason for the effusion?
Your Answer: Pneumonia
Correct Answer: Mesothelioma
Explanation:Due to his profession as a builder, this individual is at risk of being exposed to asbestos. Given the 30-year latent period and the presence of a complex effusion, it is highly probable that the underlying cause is mesothelioma.
Understanding Mesothelioma
Mesothelioma is a type of cancer that affects the mesothelial layer of the pleural cavity, which is commonly linked to asbestos exposure. Although it is rare, other mesothelial layers in the abdomen may also be affected. Symptoms of mesothelioma include dyspnoea, weight loss, chest wall pain, and clubbing. In some cases, patients may present with painless pleural effusion. It is important to note that only 20% of patients have pre-existing asbestosis, but 85-90% have a history of asbestos exposure, with a latent period of 30-40 years.
Diagnosis of mesothelioma is typically made through a chest x-ray, which may show pleural effusion or pleural thickening. A pleural CT is then performed to confirm the diagnosis. If a pleural effusion is present, fluid is sent for MC&S, biochemistry, and cytology. However, cytology is only helpful in 20-30% of cases. Local anaesthetic thoracoscopy is increasingly used to investigate cytology negative exudative effusions as it has a high diagnostic yield of around 95%. If an area of pleural nodularity is seen on CT, an image-guided pleural biopsy may be used.
Management of mesothelioma is mainly symptomatic, with industrial compensation available for those who have been exposed to asbestos. Chemotherapy and surgery may be options for those who are operable. Unfortunately, the prognosis for mesothelioma is poor, with a median survival of only 12 months.
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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 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 lobectomy
Correct 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 3
Incorrect
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Control of ventilation. Which statement is false?
Your Answer: Peripheral chemoreceptors are located in the bifurcation of the carotid arteries and arch of the aorta
Correct Answer: Central chemoreceptors respond to changes in O2
Explanation:The central chemoreceptors increase ventilation in response to an increase in H+ in the brain interstitial fluid.
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 4
Incorrect
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A 38-year-old woman visits her GP with a solitary, painless tumour in her left cheek. Upon further examination, she is diagnosed with pleomorphic adenoma. What is the recommended management for this condition?
Your Answer: Watchful waiting
Correct Answer: Surgical resection
Explanation:Surgical resection is the preferred treatment for pleomorphic adenoma, a benign tumor of the parotid gland that may undergo malignant transformation. Chemotherapy and radiotherapy are not effective in managing this condition. Additionally, salivary stone removal is not relevant to the treatment of pleomorphic adenoma.
Understanding Pleomorphic Adenoma
Pleomorphic adenoma, also known as a benign mixed tumour, is a non-cancerous growth that commonly affects the parotid gland. This type of tumour usually develops in individuals aged 40 to 60 years old. The condition is characterized by the proliferation of epithelial and myoepithelial cells of the ducts, as well as an increase in stromal components. The tumour is slow-growing, lobular, and not well encapsulated.
The clinical features of pleomorphic adenoma include a gradual onset of painless unilateral swelling of the parotid gland. The swelling is typically movable on examination rather than fixed. The management of pleomorphic adenoma involves surgical excision. The prognosis is generally good, with a recurrence rate of 1-5% with appropriate excision (parotidectomy). However, recurrence may occur due to capsular disruption during surgery. If left untreated, pleomorphic adenoma may undergo malignant transformation, occurring in 2-10% of adenomas observed for long periods. Carcinoma ex-pleomorphic adenoma is the most common type of malignant transformation, occurring most frequently as adenocarcinoma.
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This question is part of the following fields:
- Respiratory System
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Question 5
Correct
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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: 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
Incorrect
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What is the embryonic origin of the pulmonary artery?
Your Answer: Fifth pharyngeal arch
Correct Answer: Sixth pharyngeal arch
Explanation:The right pulmonary artery originates from the proximal portion of the sixth pharyngeal arch on the right side, while the distal portion of the same arch gives rise to the left pulmonary artery and the ductus arteriosus.
The Development and Contributions of Pharyngeal Arches
During the fourth week of embryonic growth, a series of mesodermal outpouchings develop from the pharynx, forming the pharyngeal arches. These arches fuse in the ventral midline, while pharyngeal pouches form on the endodermal side between the arches. There are six pharyngeal arches, with the fifth arch not contributing any useful structures and often fusing with the sixth arch.
Each pharyngeal arch has its own set of muscular and skeletal contributions, as well as an associated endocrine gland, artery, and nerve. The first arch contributes muscles of mastication, the maxilla, Meckel’s cartilage, and the incus and malleus bones. The second arch contributes muscles of facial expression, the stapes bone, and the styloid process and hyoid bone. The third arch contributes the stylopharyngeus muscle, the greater horn and lower part of the hyoid bone, and the thymus gland. The fourth arch contributes the cricothyroid muscle, all intrinsic muscles of the soft palate, the thyroid and epiglottic cartilages, and the superior parathyroids. The sixth arch contributes all intrinsic muscles of the larynx (except the cricothyroid muscle), the cricoid, arytenoid, and corniculate cartilages, and is associated with the pulmonary artery and recurrent laryngeal nerve.
Overall, the development and contributions of pharyngeal arches play a crucial role in the formation of various structures in the head and neck region.
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This question is part of the following fields:
- Respiratory System
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Question 7
Incorrect
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A 26-year-old man is brought to the emergency department after being rescued at sea following a sailing accident. He is currently unresponsive with a Glasgow Coma Score of 9 (E2 V3 M4).
His vital signs include a heart rate of 110 beats per minute, blood pressure of 110/76 mmHg, oxygen saturation of 93%, and temperature of 34.8 ºC. An ECG is unremarkable and venous blood indicates type 2 respiratory failure. The patient's oxygen dissociation curve shows a leftward shift.
What is the cause of the leftward shift in this 26-year-old patient's oxygen dissociation curve?Your Answer: Hypoxaemia
Correct Answer: Hypothermia
Explanation:The only answer that causes a leftward shift in the oxygen dissociation curve is hypothermia. When tissues undergo aerobic respiration, they generate heat, which changes the shape of the haemoglobin molecule and reduces its affinity for oxygen. This results in the release of oxygen at respiring tissues. In contrast, lower temperatures in the lungs cause a leftward shift in the oxygen dissociation curve, which increases the binding of oxygen to haemoglobin.
Hypercapnia is not the correct answer because it causes a rightward shift in the oxygen dissociation curve. Hypercapnia lowers blood pH, which changes the shape of haemoglobin and reduces its affinity for oxygen.
Hypoxaemia is not the correct answer because the partial pressure of oxygen does not affect the oxygen dissociation curve. The partial pressure of oxygen does not change the affinity of haemoglobin for oxygen.
Increased concentration of 2,3-diphosphoglycerate (2,3-DPG) is not the correct answer because higher concentrations of 2,3-DPG reduce haemoglobin’s affinity for oxygen, causing a right shift in 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 8
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 9
Incorrect
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A 42-year-old man from Turkey visits his doctor complaining of chronic breathlessness and a dry cough that has been worsening over the past 7 months. He has no significant medical history except for an allergy to penicillin. He is a non-smoker and does not consume alcohol. He works as a taxi driver and lives alone, but he is an avid collector of exotic pigeons and enjoys a cup of coffee every morning. The doctor suspects that his symptoms may be due to exposure to what causes pigeon fancier's lung?
Your Answer: Mycobacterium avium
Correct Answer: Avian proteins
Explanation:Bird fanciers’ lung is caused by avian proteins found in bird droppings, which can lead to hypersensitivity pneumonitis. This is a type of pulmonary disorder that results from an inflammatory reaction to inhaling an allergen, which can be organic or inorganic particles such as animal or plant proteins, certain chemicals, or microbes. Similarly, other types of lung diseases such as tobacco worker’s lung, farmer’s lung, and hot tub lung are also caused by exposure to specific allergens in the environment.
Extrinsic allergic alveolitis, also known as hypersensitivity pneumonitis, is a condition that occurs when the lungs are damaged due to hypersensitivity to inhaled organic particles. This damage is thought to be caused by immune-complex mediated tissue damage, although delayed hypersensitivity may also play a role. Examples of this condition include bird fanciers’ lung, farmers lung, malt workers’ lung, and mushroom workers’ lung. Symptoms can be acute or chronic and include dyspnoea, dry cough, fever, lethargy, and weight loss. Diagnosis is made through imaging, bronchoalveolar lavage, and serologic assays for specific IgG antibodies. Management involves avoiding the triggering factors and oral glucocorticoids.
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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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Mrs. Johnson is an 82-year-old woman who visited her General practitioner complaining of gradual worsening shortness of breath over the past two months. During the medical history, it was discovered that she has had Chronic Obstructive Pulmonary Disease (COPD) for 20 years.
Upon examination, there are no breath sounds at both lung bases and a stony dull note to percussion over the same areas. Based on this clinical scenario, what is the probable cause of her recent exacerbation of shortness of breath?Your Answer: Pulmonary oedema secondary to heart failure
Correct Answer: Pleural transudate effusion secondary to cor pulmonale
Explanation:The most likely cause of a pleural transudate is heart failure. This is due to the congestion of blood into the systemic venous circulation, which can result from long-standing COPD and increase in pulmonary vascular resistance leading to right-sided heart failure or cor pulmonale. Other options such as infective exacerbation of COPD or pulmonary edema secondary to heart failure are less likely to explain the clinical signs. Pleural exudate effusion secondary to cor pulmonale is also not the most appropriate answer as it would cause a transudate pleural effusion, not an exudate.
Understanding the Causes and Features of Pleural Effusion
Pleural effusion is a medical condition characterized by the accumulation of fluid in the pleural space, which is the area between the lungs and the chest wall. The causes of pleural effusion can be classified into two types: transudate and exudate. Transudate is characterized by a protein concentration of less than 30g/L and is commonly caused by heart failure, hypoalbuminemia, liver disease, and other conditions. On the other hand, exudate is characterized by a protein concentration of more than 30g/L and is commonly caused by infections, pneumonia, tuberculosis, and other conditions.
The symptoms of pleural effusion may include dyspnea, non-productive cough, and chest pain. Upon examination, patients may exhibit dullness to percussion, reduced breath sounds, and reduced chest expansion. It is important to identify the underlying cause of pleural effusion to determine the appropriate treatment plan. Early diagnosis and treatment 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 11
Incorrect
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A 68-year-old man arrives at the Emergency Department complaining of sharp and stabbing central chest pain that radiates to his back, neck, and left shoulder. He reports feeling feverish and states that sitting forward relieves the pain while lying down worsens it. The patient also mentions a recent hospitalization for a heart attack three weeks ago. During auscultation at the left sternal border, a scratchy sound is heard while the patient leans forward and holds his breath. His ECG shows widespread ST-segment saddle elevation and PR-segment depression. Can you identify the nerve responsible for his shoulder pain?
Your Answer: Vagus nerve
Correct Answer: Phrenic nerve
Explanation:The referred pain to the shoulder in this case is likely caused by Dressler’s syndrome, a type of pericarditis that occurs after a heart attack. The scratchy sound heard during auscultation is a pericardial friction rub, which is a common characteristic of pericarditis. The phrenic nerve, which supplies the pericardium, travels from the neck down through the thoracic cavity and can cause referred pain to the shoulder in cases of pericarditis.
The axillary nerve is responsible for innervating the teres minor and deltoid muscles, and dysfunction of this nerve can result in loss of sensation or movement in the shoulder area.
While the accessory nerve does innervate muscles in the neck that attach to the shoulder, it has a purely motor function and is not responsible for sensory input. Additionally, the referred pain in this case is not typical of musculoskeletal pain, but rather a result of pericarditis.
Injuries involving the long thoracic nerve often result in winging of the scapula and are commonly caused by axillary surgery.
Although the vagus nerve does supply parasympathetic innervation to the heart, it is not responsible for the referred pain in this case, as the pericardium is innervated by the phrenic nerve.
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 12
Incorrect
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Which one of the following nerves conveys sensory information from the nasal mucosa?
Your Answer: Glossopharyngeal
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 13
Incorrect
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A 75-year-old man visits his doctor complaining of weight loss and feeling full quickly. During the abdominal examination, the doctor notices a swollen lymph node in the left supraclavicular region. The doctor suspects that this could be a sign of gastric cancer with the spread of tumor emboli through the thoracic duct as it ascends from the abdomen into the mediastinum. Can you name the two other structures that pass through the diaphragm along with the thoracic duct?
Your Answer:
Correct Answer: Aorta and azygous vein
Explanation:The point at which the aorta, thoracic duct, and azygous vein cross the diaphragm is at T12, specifically at the aortic opening. This is also where the oesophageal branches of the left gastric veins, the vagal trunk, and the oesophagus pass through the diaphragm, at the oesophageal opening located at T10. The left phrenic nerve and sympathetic trunk have their own separate openings in the diaphragm. A lymph node in the left supraclavicular fossa, known as Virchow’s node, is a characteristic sign of early gastric carcinoma.
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 14
Incorrect
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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:
Correct 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 15
Incorrect
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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:
Correct 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 16
Incorrect
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Which of the following nerve roots provide nerve fibers to the ansa cervicalis?
Your Answer:
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 17
Incorrect
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A 27-year-old man with a history of epilepsy is admitted to the hospital after experiencing a tonic-clonic seizure. He is currently taking sodium valproate as his only medication. A venous blood gas is obtained immediately.
What are the expected venous blood gas results for this patient?Your Answer:
Correct Answer: Low pH, high lactate, low SaO2
Explanation:Acidosis shifts the oxygen dissociation curve to the right, which enhances oxygen delivery to the tissues by causing more oxygen to dissociate from Hb. postictal lactic acidosis is a common occurrence in patients with tonic-clonic seizures, and it is typically managed by monitoring for spontaneous resolution. During a seizure, tissue hypoxia can cause lactic acidosis. Therefore, a venous blood gas test for this patient should show low pH, high lactate, and low SaO2.
If the venous blood gas test shows a high pH, normal lactate, and low SaO2, it would not be consistent with postictal lactic acidosis. This result indicates alkalosis, which can be caused by gastrointestinal losses, renal losses, or Cushing syndrome.
A high pH, normal lactate, and normal SaO2 would also be inconsistent with postictal lactic acidosis because tissue hypoxia would cause an increase in lactate levels.
Similarly, low pH, high lactate, and normal SaO2 would not be expected in postictal lactic acidosis because acidosis would shift the oxygen dissociation curve to the right, decreasing the oxygen saturation of haemoglobin.
Finally, normal pH, normal lactate, and normal SaO2 are unlikely to be found in this patient shortly after a seizure. However, if the venous blood gas test was taken days after the seizure following an uncomplicated clinical course, these findings would be more plausible.
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 18
Incorrect
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A 49-year-old patient presents to the rheumatology clinic with weight loss, fever, and night sweats. The individual is also experiencing shortness of breath. The following blood test results are obtained:
- Hemoglobin (Hb): 140 g/l
- Platelets: 192 * 109/l
- White cell count (WCC): 5.3 * 109/l
- Creatinine: 154 umol/l
- Urea: 9 mmol/l
- cANCA positive
The white cell differential count is reported as normal. What is the most likely diagnosis?Your Answer:
Correct Answer: Granulomatosis with polyangiitis
Explanation:The most likely diagnosis for this patient is granulomatosis with polyangiitis, as indicated by the presence of cANCA and the involvement of multiple organs including the lungs, skin, kidneys, and upper respiratory tract. This condition is known to cause inflammation in the glomeruli, leading to renal impairment. Churg-Strauss disease and Alport’s syndrome are unlikely due to normal eosinophil levels and cANCA positivity, respectively. Goodpasture’s syndrome is also unlikely as the patient does not present with haematuria or haemoptysis.
Granulomatosis with Polyangiitis: An Autoimmune Condition
Granulomatosis with polyangiitis, previously known as Wegener’s granulomatosis, is an autoimmune condition that affects the upper and lower respiratory tract as well as the kidneys. It is characterized by a necrotizing granulomatous vasculitis. The condition presents with various symptoms such as epistaxis, sinusitis, nasal crusting, dyspnoea, haemoptysis, and rapidly progressive glomerulonephritis. Other symptoms include a saddle-shape nose deformity, vasculitic rash, eye involvement, and cranial nerve lesions.
To diagnose granulomatosis with polyangiitis, doctors perform various investigations such as cANCA and pANCA tests, chest x-rays, and renal biopsies. The cANCA test is positive in more than 90% of cases, while the pANCA test is positive in 25% of cases. Chest x-rays show a wide variety of presentations, including cavitating lesions. Renal biopsies reveal epithelial crescents in Bowman’s capsule.
The management of granulomatosis with polyangiitis involves the use of steroids, cyclophosphamide, and plasma exchange. Cyclophosphamide has a 90% response rate. The median survival rate for patients with this condition is 8-9 years.
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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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Which one of the following is not a cause of increased anion gap acidosis?
Your Answer:
Correct Answer: Acetazolamide
Explanation:Causes of anion gap acidosis can be remembered using the acronym MUDPILES, which stands for Methanol, Uraemia, DKA/AKA, Paraldehyde/phenformin, Iron/INH, Lactic acidosis, Ethylene glycol, and Salicylates.
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 20
Incorrect
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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:
Correct 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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