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Question 1
Correct
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A 67-year-old man arrives at the emergency department with a sudden onset of visual disturbance. He has a medical history of hypertension and takes amlodipine. He smokes 10 cigarettes daily.
During the eye examination, a field defect is observed in the right lower quadrant of both eyes. Apart from this, the examination is unremarkable.
What is the anatomical location of the lesion causing the vision problem?Your Answer: Left superior optic radiation
Explanation:Lesions in the parietal lobe affecting the superior optic radiations result in inferior homonymous quadrantanopias.
Understanding Visual Field Defects
Visual field defects can occur due to various reasons, including lesions in the optic tract, optic radiation, or occipital cortex. A left homonymous hemianopia indicates a visual field defect to the left, which is caused by a lesion in the right optic tract. On the other hand, homonymous quadrantanopias can be categorized into PITS (Parietal-Inferior, Temporal-Superior) and can be caused by lesions in the inferior or superior optic radiations in the temporal or parietal lobes.
When it comes to congruous and incongruous defects, the former refers to complete or symmetrical visual field loss, while the latter indicates incomplete or asymmetric visual field loss. Incongruous defects are caused by optic tract lesions, while congruous defects are caused by optic radiation or occipital cortex lesions. In cases where there is macula sparing, it is indicative of a lesion in the occipital cortex.
Bitemporal hemianopia, on the other hand, is caused by a lesion in the optic chiasm. The type of defect can indicate the location of the compression, with an upper quadrant defect being more common in inferior chiasmal compression, such as a pituitary tumor, and a lower quadrant defect being more common in superior chiasmal compression, such as a craniopharyngioma.
Understanding visual field defects is crucial in diagnosing and treating various neurological conditions. By identifying the type and location of the defect, healthcare professionals can provide appropriate interventions to improve the patient’s quality of life.
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This question is part of the following fields:
- Neurological System
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Question 2
Incorrect
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A 35-year-old woman has undergone surgery to repair a perforated tympanic membrane and is experiencing a change in her sense of taste. Which nerve is responsible for this alteration?
Your Answer: The glossopharyngeal nerve
Correct Answer: The chorda tympani nerve
Explanation:Nerves of the Ear and Tongue
The ear and tongue are innervated by several important nerves. One such nerve is the chorda tympani, which runs between the layers of the tympanic membrane and over the handle of the malleus. This nerve can be damaged during middle ear surgery and is responsible for supplying taste fibers to the anterior two-thirds of the tongue.
Another important nerve is the glossopharyngeal nerve, which provides motor innervation to the pharynx and sensation to the root of the tongue, tympanic cavity, and auditory tube. The greater petrosal nerve supplies parasympathetic innervation to the lacrimal gland and the mucosal glands lining the nasal cavity and palate.
The hypoglossal nerve is responsible for supplying motor innervation to the intrinsic and extrinsic muscles of the tongue. Lastly, the lesser petrosal nerve is a component of the glossopharyngeal nerve that carries parasympathetic fibers from the tympanic plexus to the parotid gland.
Overall, these nerves play crucial roles in the function of the ear and tongue, and any damage to them can have significant consequences.
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This question is part of the following fields:
- Clinical Sciences
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Question 3
Incorrect
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A 35-year-old man is brought to the emergency department with suspected spinal trauma following a car accident. He presents with back pain and pain in his right leg. Initial vital signs reveal a blood pressure of 125/83 mmHg and a heart rate of 83bpm. Upon examination, there is bruising on his chest and an obvious deformity in his right leg. Later that day, he suddenly experiences a severe headache and appears flushed, sweating profusely. His vital signs now show a blood pressure of 162/97mmHg and a heart rate of 51. What is the level of his injury?
Your Answer: L1
Correct Answer: T5
Explanation:Autonomic dysreflexia can occur if the spinal cord injury is at or above the T5 level. This condition is characterized by symptoms such as headache, sweating, hypertension, and bradycardia, which can be triggered by any afferent sympathetic signal, such as urinary retention or faecal impaction. A spinal injury at the level of L1 or S1 is too low to cause autonomic dysreflexia, but may affect bladder and bowel control and the use of the hip and legs.
Autonomic dysreflexia is a condition that occurs in patients who have suffered a spinal cord injury at or above the T6 spinal level. It is caused by a reflex response triggered by various stimuli, such as faecal impaction or urinary retention, which sends signals through the thoracolumbar outflow. However, due to the spinal cord lesion, the usual parasympathetic response is prevented, leading to an unbalanced physiological response. This response is characterized by extreme hypertension, flushing, and sweating above the level of the cord lesion, as well as agitation. If left untreated, severe consequences such as haemorrhagic stroke can occur. The management of autonomic dysreflexia involves removing or controlling the stimulus and treating any life-threatening hypertension and/or bradycardia.
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This question is part of the following fields:
- Neurological System
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Question 4
Correct
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A woman falls onto her neck and examination elicits signs of lateral medullary syndrome. Which description provides the correct findings?
Your Answer: Ipsilateral loss of pain and temperature in the face with dysphagia and ataxia and contra lateral loss in the body
Explanation:The lateral medullary syndrome is characterized by damage to the structures in the lateral medulla, which is supplied by the posterior inferior cerebellar artery. This can result in various examination findings, including ataxia from damage to the inferior cerebellar peduncle, dysphagia from damage to the nucleus ambiguus, and ipsilateral loss of pain and temperature from the face due to damage to the spinal trigeminal nucleus. Additionally, there may be contralateral loss of pain and temperature in the body from damage to the lateral spinothalamic tract.
In contrast, Brown-Sequard syndrome, which results from cord hemisection, is characterized by ipsilateral loss of light touch proprioception and contralateral loss of pain and temperature. Pontine stroke may present with hypertonia and contralateral neglect, while the triad of gait disturbance, urinary incontinence, and dementia is seen in normal pressure hydrocephalus. Medial medullary syndrome may present with ipsilateral tongue deviation, contralateral limb weakness, and contralateral loss of proprioception.
Understanding Lateral Medullary Syndrome
Lateral medullary syndrome, also referred to as Wallenberg’s syndrome, is a condition that arises when the posterior inferior cerebellar artery becomes blocked. This condition is characterized by a range of symptoms that affect both the cerebellum and brainstem. Cerebellar features of the syndrome include ataxia and nystagmus, while brainstem features include dysphagia, facial numbness, and cranial nerve palsy such as Horner’s. Additionally, patients may experience contralateral limb sensory loss. Understanding the symptoms of lateral medullary syndrome is crucial for prompt diagnosis and treatment.
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This question is part of the following fields:
- Neurological System
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Question 5
Incorrect
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A 35-year-old male visits his doctor complaining of a painless, enlarged lymph node. After conducting blood tests, the doctor discovers an elevated white cell count and refers the patient to an oncologist. Subsequent testing reveals that the patient has follicular lymphoma. Which gene is commonly mutated in this type of cancer?
Your Answer: C-MYC
Correct Answer: BCL-2
Explanation:Oncogenes are genes that promote cancer and are derived from normal genes called proto-oncogenes. Proto-oncogenes play a crucial role in cellular growth and differentiation. However, a gain of function in oncogenes increases the risk of cancer. Only one mutated copy of the gene is needed for cancer to occur, making it a dominant effect. Oncogenes are responsible for up to 20% of human cancers and can become oncogenes through mutation, chromosomal translocation, or increased protein expression.
In contrast, tumor suppressor genes restrict or repress cellular proliferation in normal cells. Their inactivation through mutation or germ line incorporation is implicated in various cancers, including renal, colonic, breast, and bladder cancer. Tumor suppressor genes, such as p53, offer protection by causing apoptosis of damaged cells. Other well-known genes include BRCA1 and BRCA2. Loss of function in tumor suppressor genes results in an increased risk of cancer, while gain of function in oncogenes increases the risk of cancer.
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This question is part of the following fields:
- General Principles
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Question 6
Incorrect
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A 75-year-old man experiences an urgent amputation due to severe sepsis and gangrene in his lower limbs. Following the surgery, he develops disseminated intravascular coagulation. Which clotting factor will be depleted the fastest during this process?
Your Answer: Factor III and VII
Correct Answer: Factor V and VIII
Explanation:D-I-S-S-E-M-I-N-A-T-E-D
R-Rewritten
E-Explanations
W-Widespread
R-Reporting
I-Information
T-Transmission
E-ExposureM-Multiple sources
E-Extensive dissemination
D-DistributionRewriting and disseminating information can help to ensure that it is widely understood and accessible. This can be especially important in cases where there are multiple sources of information or when the information needs to be widely distributed. In some cases, such as with DIC, disseminating information can be critical for understanding and treating the condition.
Disseminated Intravascular Coagulation: A Condition of Simultaneous Coagulation and Haemorrhage
Disseminated intravascular coagulation (DIC) is a medical condition characterized by simultaneous coagulation and haemorrhage. It is caused by the initial formation of thrombi that consume clotting factors and platelets, ultimately leading to bleeding. DIC can be caused by various factors such as infection, malignancy, trauma, liver disease, and obstetric complications.
Clinically, bleeding is usually the dominant feature of DIC, accompanied by bruising, ischaemia, and organ failure. Blood tests can reveal prolonged clotting times, thrombocytopenia, decreased fibrinogen, and increased fibrinogen degradation products. The treatment of DIC involves addressing the underlying cause and providing supportive management.
In summary, DIC is a serious medical condition that requires prompt diagnosis and management. It is important to identify the underlying cause and provide appropriate treatment to prevent further complications. With proper care and management, patients with DIC can recover and regain their health.
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This question is part of the following fields:
- Haematology And Oncology
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Question 7
Correct
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A 35-year-old woman has come in with symptoms of loin pain and dysuria and has been diagnosed with pyelonephritis. She was treated with intravenous amoxicillin and gentamicin and has responded well. The consultant has decided to follow local guidelines and switch her to oral co-trimoxazole. What are the components of this medication?
Your Answer: Trimethoprim + sulfamethoxazole
Explanation:Understanding Sulfonamides and Their Adverse Effects
Sulfonamides are a type of drug that work by inhibiting dihydropteroate synthetase. This class of drugs includes antibiotic sulfonamides such as sulfamethoxazole, sulfadiazine, and sulfisoxazole. Co-trimoxazole, a combination of sulfamethoxazole and trimethoprim, is commonly used in the management of Pneumocystis jiroveci pneumonia. Non-antibiotic sulfonamides like sulfasalazine and sulfonylureas also exist.
However, the use of co-trimoxazole may lead to adverse effects such as hyperkalaemia, headache, and rash, including the potentially life-threatening Steven-Johnson Syndrome. It is important to understand the potential risks associated with sulfonamides and to consult with a healthcare professional before taking any medication.
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This question is part of the following fields:
- General Principles
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Question 8
Incorrect
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Which one of the following statements relating to the posterior cerebral artery is false?
Your Answer: It is a branch of the basilar artery
Correct Answer: It is connected to the circle of Willis via the superior cerebellar artery
Explanation:The bifurcation of the basilar artery gives rise to the posterior cerebral arteries, which are linked to the circle of Willis through the posterior communicating artery.
These arteries provide blood supply to the occipital lobe and a portion of the temporal lobe.
The Circle of Willis is an anastomosis formed by the internal carotid arteries and vertebral arteries on the bottom surface of the brain. It is divided into two halves and is made up of various arteries, including the anterior communicating artery, anterior cerebral artery, internal carotid artery, posterior communicating artery, and posterior cerebral arteries. The circle and its branches supply blood to important areas of the brain, such as the corpus striatum, internal capsule, diencephalon, and midbrain.
The vertebral arteries enter the cranial cavity through the foramen magnum and lie in the subarachnoid space. They then ascend on the anterior surface of the medulla oblongata and unite to form the basilar artery at the base of the pons. The basilar artery has several branches, including the anterior inferior cerebellar artery, labyrinthine artery, pontine arteries, superior cerebellar artery, and posterior cerebral artery.
The internal carotid arteries also have several branches, such as the posterior communicating artery, anterior cerebral artery, middle cerebral artery, and anterior choroid artery. These arteries supply blood to different parts of the brain, including the frontal, temporal, and parietal lobes. Overall, the Circle of Willis and its branches play a crucial role in providing oxygen and nutrients to the brain.
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This question is part of the following fields:
- Cardiovascular System
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Question 9
Correct
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A 35-year-old woman visits her doctor at 8 weeks of pregnancy complaining of constant nausea and vomiting. What signs should the doctor look for to rule out any underlying conditions other than hyperemesis gravidarum?
Your Answer: Abdominal pain
Explanation:Hyperemesis gravidarum is a condition that causes severe nausea and vomiting during pregnancy, leading to weight loss. Abdominal pain is not a common symptom and may indicate another gastrointestinal disorder.
Hyperemesis gravidarum is a severe form of nausea and vomiting that affects around 1% of pregnancies. It is usually experienced between 8 and 12 weeks of pregnancy but can persist up to 20 weeks. The condition is thought to be related to raised beta hCG levels and is more common in women who are obese, nulliparous, or have multiple pregnancies, trophoblastic disease, or hyperthyroidism. Smoking is associated with a decreased incidence of hyperemesis.
The Royal College of Obstetricians and Gynaecologists recommend that a woman must have a 5% pre-pregnancy weight loss, dehydration, and electrolyte imbalance before a diagnosis of hyperemesis gravidarum can be made. Validated scoring systems such as the Pregnancy-Unique Quantification of Emesis (PUQE) score can be used to classify the severity of NVP.
Management of hyperemesis gravidarum involves using antihistamines as a first-line treatment, with oral cyclizine or oral promethazine being recommended by Clinical Knowledge Summaries. Oral prochlorperazine is an alternative, while ondansetron and metoclopramide may be used as second-line treatments. Ginger and P6 (wrist) acupressure can be tried, but there is little evidence of benefit. Admission may be needed for IV hydration.
Complications of hyperemesis gravidarum can include Wernicke’s encephalopathy, Mallory-Weiss tear, central pontine myelinolysis, acute tubular necrosis, and fetal growth restriction, pre-term birth, and cleft lip/palate (if ondansetron is used during the first trimester). The NICE Clinical Knowledge Summaries recommend considering admission if a woman is unable to keep down liquids or oral antiemetics, has ketonuria and/or weight loss (greater than 5% of body weight), or has a confirmed or suspected comorbidity that may be adversely affected by nausea and vomiting.
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This question is part of the following fields:
- Reproductive System
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Question 10
Correct
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A 2-day-old girl presents with sudden hypoxia, hypotension, and acidosis. Upon examination, pulses are found in the right upper limb but not in the left upper limb or legs. What congenital abnormality is the most likely cause of these symptoms?
Your Answer: Interruption of the aortic arch
Explanation:Circulatory collapse in newborns on day 1 is often caused by duct-dependent cardiac defects such as interruption of the aortic arch or left hypoplastic heart syndrome. These defects cause hypoxia, acidosis, and hypotension. Interruption of the aortic arch presents with upper limb pulses, while left hypoplastic heart syndrome presents with absent upper limb pulses. Anomalous pulmonary venous circulation and tetralogy of Fallot are not associated with early circulation collapse. Coarctation is a non-cyanotic defect that may be detected by weak femoral pulses, upper limb hypertension, or a pansystolic subclavicular/subscapular murmur.
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This question is part of the following fields:
- Paediatrics
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Question 11
Correct
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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: 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 12
Correct
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A 10-year-old girl comes to the clinic with a painful left ankle following a fall. An x-ray reveals a fracture that runs through the tibial growth plate and metaphysis. What Salter-Harris fracture classification does this injury fall under?
Your Answer: II
Explanation:Type II Salter-Harris Fractures
The Salter-Harris classification system is a way to categorize fractures that involve the growth plate or physis. These types of fractures are common in children and teenagers whose growth plates are still open. Type II Salter-Harris fractures are the most common, accounting for 75% of all growth plate fractures. This type of fracture involves a defect that runs through the growth plate and then the metaphysis.
To put it simply, a Type II Salter-Harris fracture occurs when a bone breaks through the growth plate and into the surrounding bone tissue. This type of fracture is often caused by a sudden impact or trauma to the affected area. It is important to diagnose and treat Type II fractures promptly to prevent any long-term complications, such as growth abnormalities or joint problems.
In summary, Type II Salter-Harris fractures are a common type of growth plate fracture that involves a defect running through the growth plate and then the metaphysis. These fractures can have long-term consequences if not treated properly, making prompt diagnosis and treatment essential.
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This question is part of the following fields:
- Rheumatology
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Question 13
Correct
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A father brings his 14-year-old son into the Emergency Department, who he witnessed having a 'fit' 30 minutes ago. This occurred as his son was getting up from his chair. The father noticed some shaking of his son's arms, lasting approximately 10 minutes.
His son has been very stressed with school projects over the past week, staying up late and often missing meals. His son's past medical and developmental history is non-significant.
On examination, the son is alert and responsive.
What are the associated factors with this condition?Your Answer: Short postictal period
Explanation:The recovery from syncopal episodes is rapid and the postictal period is short. In contrast, seizures have a much longer postictal period. The stem suggests that the syncope may be due to exam stress and poor nutrition habits. One way to differentiate between seizures and syncope is by the length of the postictal period, with syncope having a quick recovery. Lip smacking is not associated with syncope, but rather with focal seizures of the temporal lobe. The 10-minute postictal period described in the stem is not consistent with a seizure.
Epilepsy is a neurological condition that causes recurrent seizures. In the UK, around 500,000 people have epilepsy, and two-thirds of them can control their seizures with antiepileptic medication. While epilepsy usually occurs in isolation, certain conditions like cerebral palsy, tuberous sclerosis, and mitochondrial diseases have an association with epilepsy. It’s important to note that seizures can also occur due to other reasons like infection, trauma, or metabolic disturbance.
Seizures can be classified into focal seizures, which start in a specific area of the brain, and generalised seizures, which involve networks on both sides of the brain. Patients who have had generalised seizures may experience biting their tongue or incontinence of urine. Following a seizure, patients typically have a postictal phase where they feel drowsy and tired for around 15 minutes.
Patients who have had their first seizure generally undergo an electroencephalogram (EEG) and neuroimaging (usually a MRI). Most neurologists start antiepileptics following a second epileptic seizure. Antiepileptics are one of the few drugs where it is recommended that we prescribe by brand, rather than generically, due to the risk of slightly different bioavailability resulting in a lowered seizure threshold.
Patients who drive, take other medications, wish to get pregnant, or take contraception need to consider the possible interactions of the antiepileptic medication. Some commonly used antiepileptics include sodium valproate, carbamazepine, lamotrigine, and phenytoin. In case of a seizure that doesn’t terminate after 5-10 minutes, medication like benzodiazepines may be administered to terminate the seizure. If a patient continues to fit despite such measures, they are said to have status epilepticus, which is a medical emergency requiring hospital treatment.
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This question is part of the following fields:
- Neurological System
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Question 14
Correct
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A 45-year-old man was admitted to critical care with urinary sepsis. He was intubated and ventilated and treated with intravenous fluids and antibiotics. About a week later, he developed an oxygen requirement, and the medical team observed crackles at the right base.
What are the laboratory characteristics linked with Pseudomonas aeruginosa, as indicated by a sputum culture showing Gram-negative rod?Your Answer: Non-lactose fermenting
Explanation:Lab findings that suggest the presence of Pseudomonas aeruginosa include a gram-negative rod, non-lactose fermenting, and positive for oxidase. In this case, the patient likely acquired a nosocomial infection with Pseudomonas aeruginosa, which is a common cause of hospital-acquired pneumonia or ventilator-acquired pneumonia. It is important to note that Pseudomonas aeruginosa does not cause haemolysis, unlike Group A Streptococcus, which exhibits beta-haemolysis. Streptococcus pneumoniae, on the other hand, is a gram-positive coccus that causes alpha-haemolysis and is a less likely cause of hospital/ventilator-acquired pneumonia.
Pseudomonas aeruginosa: A Gram-negative Rod Causing Various Infections
Pseudomonas aeruginosa is a type of bacteria that is commonly found in the environment. It is a Gram-negative rod that can cause a range of infections in humans. Some of the infections it causes include chest infections, skin infections such as burns and wound infections, otitis externa, and urinary tract infections.
In the laboratory, Pseudomonas aeruginosa is identified as a Gram-negative rod that does not ferment lactose and is oxidase positive. The bacteria produce both an endotoxin and exotoxin A. The endotoxin causes fever and shock, while exotoxin A inhibits protein synthesis by catalyzing ADP-ribosylation of elongation factor EF-2.
Overall, Pseudomonas aeruginosa is a pathogenic bacteria that can cause a variety of infections in humans. Its ability to produce toxins makes it particularly dangerous and difficult to treat. Proper hygiene and infection control measures can help prevent the spread of this bacteria.
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This question is part of the following fields:
- General Principles
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Question 15
Incorrect
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Samantha, a 26-year-old female, arrives at the emergency department after a high impact injury from a fall. She reports experiencing pain in her right leg.
Upon examination, Samantha's neurovascular status is intact, and an X-ray is ordered. The X-ray reveals a posterior dislocation of the hip, with no accompanying fractures. The dislocation is reduced while Samantha is under anesthesia.
What is the usual indication observed during the examination of Samantha's leg?Your Answer: Leg is flexed and externally rotated
Correct Answer: Leg is internally rotated
Explanation:The position of the leg in hip dislocations depends on whether it is an anterior or posterior dislocation. In the case of a posterior dislocation, as specified in the question, the leg is internally rotated. However, if it were an anterior dislocation, the leg would be externally rotated. It is important to note that the leg is not in its normal anatomical position in either case. Additionally, in a posterior dislocation, the leg may also be flexed. The option of external rotation is incorrect for a posterior dislocation. Finally, while the leg may be internally rotated in a posterior dislocation, it is usually flexed rather than hyperextended.
Understanding Hip Dislocation: Types, Management, Complications, and Prognosis
Hip dislocation is a painful condition that is often caused by direct trauma, such as road traffic accidents or falls from a significant height. This condition can be associated with other fractures and life-threatening injuries due to the large forces required to cause most traumatic hip dislocations. Therefore, prompt diagnosis and appropriate management are crucial to reduce morbidity.
There are three types of hip dislocation: posterior, anterior, and central. Posterior dislocation is the most common, accounting for 90% of cases. It is characterized by a shortened, adducted, and internally rotated affected leg. On the other hand, anterior dislocation presents with an abducted and externally rotated affected leg, while central dislocation is rare.
The management of hip dislocation follows the ABCDE approach, with analgesia as a priority. A reduction under general anaesthetic within four hours is recommended to reduce the risk of avascular necrosis. Long-term management involves physiotherapy to strengthen the surrounding muscles.
Complications of hip dislocation include sciatic or femoral nerve injury, avascular necrosis, osteoarthritis (more common in older patients), and recurrent dislocation due to damage of supporting ligaments.
The prognosis of hip dislocation depends on the timing of reduction and the extent of joint damage. It takes about two to three months for the hip to heal after a traumatic dislocation. The best prognosis is when the hip is reduced less than 12 hours post-injury and when there is less damage to the joint.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 16
Correct
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A 29-year-old male is admitted after a car accident. During examination, his heart rate is found to be 125 beats/min, and his blood pressure is 120/105 mmHg. Upon palpation, his abdomen is tense and tender. The diagnosis is hypovolemic shock. Which receptor stimulation has led to compensation for the blood loss?
Your Answer: Alpha 1 adrenergic
Explanation:Activation of alpha 1 adrenergic receptors leads to the contraction of smooth muscles. This causes vasoconstriction in the skin, gut, and kidney arterioles, increasing total peripheral resistance and mean arterial pressure. It also helps to improve perfusion of vital organs such as the brain, heart, and lungs during the fight or flight response.
On the other hand, activation of beta 2 adrenergic receptors results in the dilation of smooth muscles, such as bronchodilation. Activation of beta 3 adrenergic receptors enhances lipolysis in adipose tissue. Activation of alpha 2 adrenergic receptors inhibits the release of noradrenaline, providing negative feedback.
Activation of the muscarinic M2 acetylcholine receptor decreases heart rate, which could worsen compensation.
Adrenergic receptors are a type of G protein-coupled receptors that respond to the catecholamines epinephrine and norepinephrine. These receptors are primarily involved in the sympathetic nervous system. There are four types of adrenergic receptors: α1, α2, β1, and β2. Each receptor has a different potency order and primary action. The α1 receptor responds equally to norepinephrine and epinephrine, causing smooth muscle contraction. The α2 receptor has mixed effects and responds equally to both catecholamines. The β1 receptor responds equally to epinephrine and norepinephrine, causing cardiac muscle contraction. The β2 receptor responds much more strongly to epinephrine than norepinephrine, causing smooth muscle relaxation.
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This question is part of the following fields:
- General Principles
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Question 17
Correct
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A 40-year-old man visits his GP with his wife who is worried about his behavior. Upon further inquiry, the wife reveals that her husband has been displaying erratic and impulsive behavior for the past 4 months. She also discloses that he inappropriately touched a family friend, which is out of character for him. When asked about his medical history, the patient mentions that he used to be an avid motorcyclist but had a severe accident 6 months ago, resulting in a month-long hospital stay. He denies experiencing flashbacks and reports generally good mood. What is the most probable cause of his symptoms?
Your Answer: Frontal lobe injury
Explanation:Disinhibition can be a result of frontal lobe lesions.
Based on his recent accident, it is probable that the man has suffered from a frontal lobe injury. Such injuries can cause changes in behavior, including impulsiveness and a lack of inhibition.
If the injury were to the occipital lobe, it would likely result in vision loss.
The patient’s denial of flashbacks and positive mood make it unlikely that he has PTSD.
Injuries to the parietal and temporal lobes can lead to communication difficulties and sensory perception problems.
Brain lesions can be localized based on the neurological disorders or features that are present. The gross anatomy of the brain can provide clues to the location of the lesion. For example, lesions in the parietal lobe can result in sensory inattention, apraxias, astereognosis, inferior homonymous quadrantanopia, and Gerstmann’s syndrome. Lesions in the occipital lobe can cause homonymous hemianopia, cortical blindness, and visual agnosia. Temporal lobe lesions can result in Wernicke’s aphasia, superior homonymous quadrantanopia, auditory agnosia, and prosopagnosia. Lesions in the frontal lobes can cause expressive aphasia, disinhibition, perseveration, anosmia, and an inability to generate a list. Lesions in the cerebellum can result in gait and truncal ataxia, intention tremor, past pointing, dysdiadokinesis, and nystagmus.
In addition to the gross anatomy, specific areas of the brain can also provide clues to the location of a lesion. For example, lesions in the medial thalamus and mammillary bodies of the hypothalamus can result in Wernicke and Korsakoff syndrome. Lesions in the subthalamic nucleus of the basal ganglia can cause hemiballism, while lesions in the striatum (caudate nucleus) can result in Huntington chorea. Parkinson’s disease is associated with lesions in the substantia nigra of the basal ganglia, while lesions in the amygdala can cause Kluver-Bucy syndrome, which is characterized by hypersexuality, hyperorality, hyperphagia, and visual agnosia. By identifying these specific conditions, doctors can better localize brain lesions and provide appropriate treatment.
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This question is part of the following fields:
- Neurological System
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Question 18
Incorrect
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A 29-year-old woman is brought in after overdosing on diazepam during a fight with her partner. She is disoriented, confused, and has difficulty maintaining balance. Her breathing is shallow and slow. Her vital signs show a heart rate of 50/min, blood pressure of 98/50 mmHg, respiratory rate of 9/min, and temperature of 36.5ºC. The medical team intubates her and secures her airway.
What antidote could be administered as part of her treatment?Your Answer: Fomepizole
Correct Answer: Flumazenil
Explanation:Flumazenil is the antidote used to treat severe benzodiazepine overdose. If the patient’s condition does not improve with supportive measures, flumazenil may be administered.
Methanol poisoning is treated with fomepizole, while opioid overdose is treated with naloxone. Chlordiazepoxide is also a benzodiazepine.
The management of overdoses and poisonings involves specific treatments for each toxin. For example, in cases of paracetamol overdose, activated charcoal may be given if ingested within an hour, and N-acetylcysteine or liver transplantation may be necessary. Salicylate overdose may require urinary alkalinization with IV bicarbonate or haemodialysis. Opioid/opiate overdose can be treated with naloxone, while benzodiazepine overdose may require flumazenil, although this is only used in severe cases due to the risk of seizures. Tricyclic antidepressant overdose may require IV bicarbonate to reduce the risk of seizures and arrhythmias, while lithium toxicity may respond to volume resuscitation with normal saline or haemodialysis. Warfarin overdose can be treated with vitamin K or prothrombin complex, while heparin overdose may require protamine sulphate. Beta-blocker overdose may require atropine or glucagon. Ethylene glycol poisoning can be treated with fomepizole or ethanol, while methanol poisoning may require the same treatment or haemodialysis. Organophosphate insecticide poisoning can be treated with atropine, and digoxin overdose may require digoxin-specific antibody fragments. Iron overdose may require desferrioxamine, and lead poisoning may require dimercaprol or calcium edetate. Carbon monoxide poisoning can be treated with 100% oxygen or hyperbaric oxygen, while cyanide poisoning may require hydroxocobalamin or a combination of amyl nitrite, sodium nitrite, and sodium thiosulfate.
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This question is part of the following fields:
- General Principles
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Question 19
Correct
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As a 2nd-year medical student on placement in a GP surgery in early February, you encounter a 79-year-old woman who comes in for a follow-up appointment due to fatigue. During the consultation, the GP reviews her blood tests and discovers a vitamin deficiency. The GP informs the patient that if left untreated, this deficiency can lead to bone softening. Can you explain how this vitamin increases serum calcium levels in the body?
Your Answer: Raises absorption of calcium in the small intestine
Explanation:The primary way in which vitamin D increases serum calcium levels is by enhancing its absorption through the small intestine.
Understanding Vitamin D
Vitamin D is a type of vitamin that is soluble in fat and is essential for the metabolism of calcium and phosphate in the body. It is converted into calcifediol in the liver and then into calcitriol, which is the active form of vitamin D, in the kidneys. Vitamin D can be obtained from two sources: vitamin D2, which is found in plants, and vitamin D3, which is present in dairy products and can also be synthesized by the skin when exposed to sunlight.
The primary function of vitamin D is to increase the levels of calcium and phosphate in the blood. It achieves this by increasing the absorption of calcium in the gut and the reabsorption of calcium in the kidneys. Vitamin D also stimulates osteoclastic activity, which is essential for bone growth and remodeling. Additionally, it increases the reabsorption of phosphate in the kidneys.
A deficiency in vitamin D can lead to two conditions: rickets in children and osteomalacia in adults. Rickets is characterized by soft and weak bones, while osteomalacia is a condition where the bones become weak and brittle. Therefore, it is crucial to ensure that the body receives an adequate amount of vitamin D to maintain healthy bones and overall health.
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This question is part of the following fields:
- General Principles
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Question 20
Correct
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A 60-year-old male is referred to the medical assessment unit by his physician suspecting a UTI. He has a permanent catheter in place due to urinary retention caused by benign prostatic hypertrophy. His blood test results reveal hypercalcemia. An ultrasound Doppler scan of his neck displays a distinct sonolucent signal indicating hyperactive parathyroid tissue and noticeable vasculature, which is likely the parathyroid veins. What is the structure that the parathyroid veins empty into?
Your Answer: Thyroid plexus of veins
Explanation:The veins of the parathyroid gland drain into the thyroid plexus of veins, as opposed to other possible drainage routes.
The cavernous sinus is a dural venous sinus that creates a cavity called the lateral sellar compartment, which is bordered by the temporal and sphenoid bones.
The brachiocephalic vein is formed by the merging of the subclavian and internal jugular veins, and also receives drainage from the left and right internal thoracic vein.
The external vertebral venous plexuses, which are most prominent in the cervical region, consist of anterior and posterior plexuses that freely anastomose with each other. The anterior plexuses are located in front of the vertebrae bodies, communicate with the basivertebral and intervertebral veins, and receive tributaries from the vertebral bodies. The posterior plexuses are situated partly on the posterior surfaces of the vertebral arches and their processes, and partly between the deep dorsal muscles.
The suboccipital venous plexus is responsible for draining deoxygenated blood from the back of the head, and is connected to the external vertebral venous plexuses.
Anatomy and Development of the Parathyroid Glands
The parathyroid glands are four small glands located posterior to the thyroid gland within the pretracheal fascia. They develop from the third and fourth pharyngeal pouches, with those derived from the fourth pouch located more superiorly and associated with the thyroid gland, while those from the third pouch lie more inferiorly and may become associated with the thymus.
The blood supply to the parathyroid glands is derived from the inferior and superior thyroid arteries, with a rich anastomosis between the two vessels. Venous drainage is into the thyroid veins. The parathyroid glands are surrounded by various structures, with the common carotid laterally, the recurrent laryngeal nerve and trachea medially, and the thyroid anteriorly. Understanding the anatomy and development of the parathyroid glands is important for their proper identification and preservation during surgical procedures.
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This question is part of the following fields:
- Cardiovascular System
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Question 21
Correct
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A patient in his late 40s visits his GP complaining of intense shoulder pain that radiates to the scapula area. Despite a thorough shoulder examination revealing no joint issues, the patient is referred for additional tests. Imaging studies reveal a bronchogenic apical lung tumor that has caused lesions in the brachial plexus and extends towards the superior cervical and stellate ganglia. If these two structures are compressed, what signs are most likely to occur?
Your Answer: Ptosis, miosis, anhydrosis
Explanation:The superior cervical ganglion (SCG) is a component of the sympathetic nervous system that solely innervates the head and neck. Its functions include innervating eye structures, and damage or compression of the SCG can lead to Horner’s syndrome, which is characterized by ptosis, miosis, and anhydrosis. This syndrome occurs due to the unopposed action of the parasympathetic system on the eye, as the sympathetic innervation is impaired.
Damage to the external laryngeal nerve, a branch of the superior laryngeal nerve, can result in a monotonous voice. However, this nerve does not originate from the SCG, so it is unlikely to affect the voice.
As the SCG is part of the sympathetic nervous system, its damage impairs sympathetic responses and leads to unopposed parasympathetic innervation. This can cause miosis (constriction) of the eye, not mydriasis (dilation).
Sweating is caused by the action of the sympathetic nervous system, so damage to the SCG would most likely result in anhydrosis (lack of sweat) of the face, rather than hyperhidrosis (excessive sweating).
Hoarse voice can result from damage to the recurrent laryngeal nerve, which is not related to the SCG, so it is unlikely to affect the voice.
Horner’s syndrome is a condition characterized by several features, including a small pupil (miosis), drooping of the upper eyelid (ptosis), a sunken eye (enophthalmos), and loss of sweating on one side of the face (anhidrosis). The cause of Horner’s syndrome can be determined by examining additional symptoms. For example, congenital Horner’s syndrome may be identified by a difference in iris color (heterochromia), while anhidrosis may be present in central or preganglionic lesions. Pharmacologic tests, such as the use of apraclonidine drops, can also be helpful in confirming the diagnosis and identifying the location of the lesion. Central lesions may be caused by conditions such as stroke or multiple sclerosis, while postganglionic lesions may be due to factors like carotid artery dissection or cluster headaches. It is important to note that the appearance of enophthalmos in Horner’s syndrome is actually due to a narrow palpebral aperture rather than true enophthalmos.
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This question is part of the following fields:
- Neurological System
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Question 22
Correct
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A 38-year-old male is admitted to the hospital after a work-related injury resulting in deep partial-thickness burns covering 18% of his body. The anaesthetist is consulted for pain management, but due to the extent of the burns, IV access is not possible. As an alternative, the anaesthetist decides to administer intramuscular ketamine to control the patient's pain. What is the mechanism of action of this medication?
Your Answer: N-methyl D-aspartic acid (NMDA) receptor antagonist
Explanation:Overview of General Anaesthetics
General anaesthetics are drugs used to induce a state of unconsciousness in patients undergoing surgical procedures. They can be administered through inhalation or intravenous injection. Inhaled anaesthetics, such as isoflurane, desflurane, sevoflurane, and nitrous oxide, work by acting on various receptors in the brain, including GABAA, glycine, NDMA, nACh, and 5-HT3. These drugs can cause adverse effects such as myocardial depression, malignant hyperthermia, and increased pressure in gas-filled body compartments. Intravenous anaesthetics, such as propofol, thiopental, etomidate, and ketamine, also act on receptors in the brain, but through different mechanisms. These drugs can cause adverse effects such as pain on injection, hypotension, laryngospasm, and hallucinations. Each drug has its own unique properties and is chosen based on the patient’s medical history and the type of surgery being performed.
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This question is part of the following fields:
- General Principles
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Question 23
Correct
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As a medical student observing a parathyroidectomy in the short-stay surgical theatre, you witness the ligation of blood vessels supplying the parathyroid glands. The ENT consultant requests you to identify the arteries responsible for supplying oxygenated blood to the parathyroid gland. Can you correctly name these arteries?
Your Answer: Superior and inferior thyroid arteries
Explanation:The superior and inferior thyroid arteries provide oxygenated blood supply to the parathyroid glands. The existence of inferior parathyroid arteries and superior parathyroid arteries is not supported by anatomical evidence. While a middle thyroid artery may exist in some individuals, it is a rare variation that is not relevant to the question at hand.
Anatomy and Development of the Parathyroid Glands
The parathyroid glands are four small glands located posterior to the thyroid gland within the pretracheal fascia. They develop from the third and fourth pharyngeal pouches, with those derived from the fourth pouch located more superiorly and associated with the thyroid gland, while those from the third pouch lie more inferiorly and may become associated with the thymus.
The blood supply to the parathyroid glands is derived from the inferior and superior thyroid arteries, with a rich anastomosis between the two vessels. Venous drainage is into the thyroid veins. The parathyroid glands are surrounded by various structures, with the common carotid laterally, the recurrent laryngeal nerve and trachea medially, and the thyroid anteriorly. Understanding the anatomy and development of the parathyroid glands is important for their proper identification and preservation during surgical procedures.
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This question is part of the following fields:
- Cardiovascular System
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Question 24
Incorrect
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A 47-year-old woman is recuperating in the ICU after undergoing a Whipples surgery. She has a central venous line inserted. What will cause the 'y' descent on the waveform trace?
Your Answer: Opening of the pulmonary valve
Correct Answer: Emptying of the right atrium
Explanation:The JVP waveform consists of 3 upward deflections and 2 downward deflections. The upward deflections include the a wave, which represents atrial contraction, the c wave, which represents ventricular contraction, and the v wave, which represents atrial venous filling. The downward deflections include the x wave, which occurs when the atrium relaxes and the tricuspid valve moves down, and the y wave, which represents ventricular filling. The y descent in the waveform indicates the emptying of the atrium and the filling of the right ventricle.
The heart has four chambers and generates pressures of 0-25 mmHg on the right side and 0-120 mmHg on the left. The cardiac output is the product of heart rate and stroke volume, typically 5-6L per minute. The cardiac impulse is generated in the sino atrial node and conveyed to the ventricles via the atrioventricular node. Parasympathetic and sympathetic fibers project to the heart via the vagus and release acetylcholine and noradrenaline, respectively. The cardiac cycle includes mid diastole, late diastole, early systole, late systole, and early diastole. Preload is the end diastolic volume and afterload is the aortic pressure. Laplace’s law explains the rise in ventricular pressure during the ejection phase and why a dilated diseased heart will have impaired systolic function. Starling’s law states that an increase in end-diastolic volume will produce a larger stroke volume up to a point beyond which stroke volume will fall. Baroreceptor reflexes and atrial stretch receptors are involved in regulating cardiac output.
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This question is part of the following fields:
- Cardiovascular System
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Question 25
Correct
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Which receptor is predominantly targeted by noradrenaline?
Your Answer: α 1 receptors
Explanation:Adrenaline is derived from noradrenaline and has a potent effect on α 1 receptors, although it can also increase myocardial contractility. When administered through infusions, it causes vasoconstriction and a rise in overall peripheral resistance. Noradrenaline is the preferred inotrope for treating septic shock.
Inotropes are drugs that primarily increase cardiac output and are different from vasoconstrictor drugs that are used for peripheral vasodilation. Catecholamine type agents are commonly used in inotropes and work by increasing cAMP levels through adenylate cyclase stimulation. This leads to intracellular calcium ion mobilisation and an increase in the force of contraction. Adrenaline works as a beta adrenergic receptor agonist at lower doses and an alpha receptor agonist at higher doses. Dopamine causes dopamine receptor-mediated renal and mesenteric vascular dilatation and beta 1 receptor agonism at higher doses, resulting in increased cardiac output. Dobutamine is a predominantly beta 1 receptor agonist with weak beta 2 and alpha receptor agonist properties. Noradrenaline is a catecholamine type agent and predominantly acts as an alpha receptor agonist and serves as a peripheral vasoconstrictor. Milrinone is a phosphodiesterase inhibitor that acts specifically on the cardiac phosphodiesterase and increases cardiac output.
The cardiovascular receptor action of inotropes varies depending on the drug. Adrenaline and noradrenaline act on alpha and beta receptors, with adrenaline acting as a beta adrenergic receptor agonist at lower doses and an alpha receptor agonist at higher doses. Dobutamine acts predominantly on beta 1 receptors with weak beta 2 and alpha receptor agonist properties. Dopamine acts on dopamine receptors, causing renal and spleen vasodilation and beta 1 receptor agonism at higher doses. The minor receptor effects are shown in brackets. The effects of receptor binding include vasoconstriction for alpha-1 and alpha-2 receptors, increased cardiac contractility and heart rate for beta-1 receptors, and vasodilation for beta-2 receptors. D-1 receptors cause renal and spleen vasodilation, while D-2 receptors inhibit the release of noradrenaline. Overall, inotropes are a class of drugs that increase cardiac output through various receptor actions.
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This question is part of the following fields:
- General Principles
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Question 26
Correct
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A 32-year-old woman visits her doctor complaining of a severe, pulsating headache that began last night and is concentrated at the back of her head. She experiences intense pain when coughing. Her family has a history of Type I Chiari malformation.
The doctor suspects idiopathic intracranial hypertension and conducts a fundoscopy to check for signs of papilloedema. Before using an ophthalmoscope to examine her eyes, the doctor applies a topical medication.
What is the name of the medication used?Your Answer: Tropicamide
Explanation:Tropicamide is administered before fundoscopy to enlarge the pupils. It functions as a muscarinic receptor antagonist, inhibiting parasympathetic impulses and causing the pupil constrictor response and ciliary muscle to become paralyzed. This results in pupil dilation, which is necessary for optimal visualization of the fundus.
Fluorescein stain is utilized to evaluate the cornea for damage or the presence of foreign objects in the eye.
Pilocarpine, a muscarinic receptor agonist, causes pupillary constriction and should not be used before fundoscopy as it would hinder the visualization of the fundus.
Lidocaine is a local anesthetic that works by blocking fast voltage-gated Na channels in the neuronal cell membrane responsible for signal propagation. There is no need to apply topical lidocaine before fundoscopy.
Mydriasis, which is the enlargement of the pupil, can be caused by various factors such as third nerve palsy, Holmes-Adie pupil, traumatic iridoplegia, phaeochromocytoma, and congenital conditions. Additionally, certain drugs like topical mydriatics such as tropicamide and atropine, sympathomimetic drugs like amphetamines and cocaine, and anticholinergic drugs like tricyclic antidepressants can also cause mydriasis. It is important to note that anisocoria, which is the unequal size of pupils, can also lead to apparent mydriasis when compared to the other pupil.
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This question is part of the following fields:
- Neurological System
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Question 27
Correct
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A 67-year-old man with peripheral vascular disease is scheduled for a below knee amputation. Can you identify the compartment in the lower leg where peroneus brevis is located?
Your Answer: Lateral compartment
Explanation:The deep transverse fascia divides the leg into anterior and posterior compartments, while the interosseous membrane separates them. The lateral compartment includes the peroneus brevis muscle.
Fascial Compartments of the Leg
The leg is divided into compartments by fascial septae, which are thin layers of connective tissue. In the thigh, there are three compartments: the anterior, medial, and posterior compartments. The anterior compartment contains the femoral nerve and artery, as well as the quadriceps femoris muscle group. The medial compartment contains the obturator nerve and artery, as well as the adductor muscles and gracilis muscle. The posterior compartment contains the sciatic nerve and branches of the profunda femoris artery, as well as the hamstrings muscle group.
In the lower leg, there are four compartments: the anterior, posterior (divided into deep and superficial compartments), lateral, and deep posterior compartments. The anterior compartment contains the deep peroneal nerve and anterior tibial artery, as well as the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus tertius muscles. The posterior compartment contains the tibial nerve and posterior tibial artery, as well as the deep and superficial muscles. The lateral compartment contains the superficial peroneal nerve and peroneal artery, as well as the peroneus longus and brevis muscles. The deep posterior compartment contains the tibial nerve and posterior tibial artery, as well as the flexor hallucis longus, flexor digitorum longus, tibialis posterior, and popliteus muscles.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 28
Incorrect
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A 20-year-old man comes to the emergency department complaining of abdominal pain, vomiting, polyuria, polydipsia, and confusion that have been present for the past 12 hours. During the examination, he shows mild generalized abdominal tenderness without guarding. His breathing is observed to be deep and rapid.
The patient has a medical history of type 1 diabetes, but he confesses to being non-compliant with his insulin regimen.
What is the probable pathophysiology behind his symptoms?Your Answer: Elevated serum lactate levels
Correct Answer: Uncontrolled lipolysis which results in an excess of free fatty acids
Explanation:The cause of DKA is uncontrolled lipolysis, leading to an excess of free fatty acids that are converted to ketone bodies. This results in high levels of ketones in the urine. Hypoglycemia activates the sympathetic nervous system. Lactic acidosis is similar to DKA but lacks the presence of ketones in urine. Appendicitis can cause abdominal pain, vomiting, and urinary symptoms, but the presence of ketones in urine suggests DKA. Urinary tract infections are rare in men under 50 and typically occur with abnormal anatomy or catheterization.
Diabetic ketoacidosis (DKA) is a serious complication of type 1 diabetes mellitus, accounting for around 6% of cases. It can also occur in rare cases of extreme stress in patients with type 2 diabetes mellitus. DKA is caused by uncontrolled lipolysis, resulting in an excess of free fatty acids that are converted to ketone bodies. The most common precipitating factors of DKA are infection, missed insulin doses, and myocardial infarction. Symptoms include abdominal pain, polyuria, polydipsia, dehydration, Kussmaul respiration, and breath that smells like acetone. Diagnostic criteria include glucose levels above 11 mmol/l or known diabetes mellitus, pH below 7.3, bicarbonate below 15 mmol/l, and ketones above 3 mmol/l or urine ketones ++ on dipstick.
Management of DKA involves fluid replacement, insulin, and correction of electrolyte disturbance. Fluid replacement is necessary as most patients with DKA are deplete around 5-8 litres. Isotonic saline is used initially, even if the patient is severely acidotic. Insulin is administered through an intravenous infusion, and correction of electrolyte disturbance is necessary. Long-acting insulin should be continued, while short-acting insulin should be stopped. Complications may occur from DKA itself or the treatment, such as gastric stasis, thromboembolism, arrhythmias, acute respiratory distress syndrome, acute kidney injury, and cerebral edema. Children and young adults are particularly vulnerable to cerebral edema following fluid resuscitation in DKA and often need 1:1 nursing to monitor neuro-observations, headache, irritability, visual disturbance, focal neurology, etc.
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This question is part of the following fields:
- Endocrine System
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Question 29
Incorrect
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A 5-year-old boy presents with symptoms of right sided loin pain, lethargy and haematuria. On examination he is pyrexial and has a large mass in the right upper quadrant. What is the most probable underlying diagnosis?
Your Answer: Perinephric abscess
Correct Answer: Nephroblastoma
Explanation:Based on the symptoms presented, it is highly probable that the child has nephroblastoma, while perinephric abscess is an unlikely diagnosis. Even if an abscess were to develop, it would most likely be contained within Gerota’s fascia initially, making anterior extension improbable.
Nephroblastoma: A Childhood Cancer
Nephroblastoma, also known as Wilms tumours, is a type of childhood cancer that typically occurs in the first four years of life. The most common symptom is the presence of a mass, often accompanied by haematuria (blood in urine). In some cases, pyrexia (fever) may also occur in about 50% of patients. Unfortunately, nephroblastomas tend to metastasize early, usually to the lungs.
The primary treatment for nephroblastoma is nephrectomy, which involves the surgical removal of the affected kidney. The prognosis for younger children is generally better, with those under one year of age having an overall 5-year survival rate of 80%. It is important to seek medical attention promptly if any of the symptoms associated with nephroblastoma are present, as early detection and treatment can greatly improve the chances of a positive outcome.
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This question is part of the following fields:
- Renal System
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Question 30
Incorrect
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Which statement about receptor tyrosine kinases is accurate?
Your Answer: Tyrosine kinase receptors phosphorylate cytoplasmic proteins as part of the signal transduction
Correct Answer: Dimerisation of receptors is usually involved in activation
Explanation:Receptor Binding and Activation
Substances such as insulin, epidermal growth factor (EGF), and platelet-derived growth factor (PDGF) can bind to receptors in the body. These receptors have four domains: ligand binding, transmembrane, catalytic, and autophosphorylation domains. When an agonist binds to the receptor, it causes a change in shape, which leads to phosphorylation. This process activates the receptor and triggers a response in the body.
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This question is part of the following fields:
- Pharmacology
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Question 31
Incorrect
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In the context of acid-base balance, what compensatory mechanisms would be observed in an individual who has a pH of 7.20 (normal range: 7.35-7.45) and is experiencing metabolic acidosis?
Your Answer: Decreased respiratory rate
Correct Answer: Increased respiratory rate
Explanation:Compensation for Metabolic Acidosis
In cases of metabolic acidosis, the bicarbonate levels in the blood will be low. However, this is not considered a compensation. To increase the blood pH, the respiratory rate will increase, causing a decrease in CO2 levels. This results in a respiratory alkalosis, which compensates for the metabolic acidosis. It is important to note that there is a limit to how much an increased respiratory rate can compensate for a metabolic acidosis. Therefore, it is crucial to address the underlying cause of the metabolic acidosis to prevent further complications.
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This question is part of the following fields:
- Clinical Sciences
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Question 32
Correct
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A 25-year-old man comes to the emergency department complaining of abdominal pain and vomiting. He reports not having a bowel movement for the past five days.
His medical history includes a ruptured appendix three years ago. There is no significant medical or family history.
During the examination, you observe abdominal distension and tinkling bowel sounds.
An abdominal X-ray shows dilated loops of small bowel.
What is the leading cause of the probable diagnosis in this scenario?Your Answer: Adhesions
Explanation:The leading cause of small bowel obstruction is adhesions, which can occur due to previous abdominal surgery and cause internal surfaces to stick together. An abdominal X-ray showing dilated small bowel loops is a common indicator of this condition. While a hernia can also cause small bowel obstruction, it is less likely in this case due to the patient’s surgical history. Intussusception is rare in adults and more commonly seen in young children. Malignancy is a less common cause of small bowel obstruction, especially in patients without risk factors or demographic factors that suggest a higher likelihood of cancer.
Small bowel obstruction occurs when the small intestines are blocked, preventing the passage of food, fluids, and gas. The most common causes of this condition are adhesions resulting from previous surgeries and hernias. Symptoms include diffuse, central abdominal pain, nausea and vomiting (often bilious), constipation, and abdominal distension. Tinkling bowel sounds may also be present in early stages of obstruction. Abdominal x-ray is typically the first imaging test used to diagnose small bowel obstruction, showing distended small bowel loops with fluid levels. CT is more sensitive and considered the definitive investigation, particularly in early stages of obstruction. Management involves NBM, IV fluids, and a nasogastric tube with free drainage. Conservative management may be effective for some patients, but surgery is often necessary.
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This question is part of the following fields:
- Gastrointestinal System
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Question 33
Incorrect
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You are developing a research project investigating the pathophysiology of abetalipoproteinemia. You determine that a viable focus would be the rate-limiting enzyme involved in lipogenesis.
Which enzyme will be the target of your investigation?Your Answer: Carbamoyl phosphate synthetase I
Correct Answer: Acetyl CoA carboxylase
Explanation:The enzyme that limits the rate of lipogenesis is acetyl CoA carboxylase.
During lipogenesis, fatty acids are produced from acetyl-CoA. Acetyl CoA carboxylase is the enzyme that controls the rate of this process.
Carbamoyl phosphate synthetase I is the enzyme that limits the rate of the urea cycle.
Glycogen phosphorylase is the enzyme that controls the rate of glycogenolysis.
Isocitrate dehydrogenase is the enzyme that limits the rate of the citric acid cycle.
Rate-Determining Enzymes in Metabolic Processes
Metabolic processes involve a series of chemical reactions that occur in living organisms to maintain life. Enzymes play a crucial role in these processes by catalyzing the reactions. However, not all enzymes have the same impact on the rate of the reaction. Some enzymes are rate-determining, meaning that they control the overall rate of the process. The table above lists the rate-determining enzymes involved in common metabolic processes.
For example, in the TCA cycle, isocitrate dehydrogenase is the rate-determining enzyme. In glycolysis, phosphofructokinase-1 controls the rate of the process. In gluconeogenesis, fructose-1,6-bisphosphatase is the rate-determining enzyme. Similarly, glycogen synthase controls the rate of glycogenesis, while glycogen phosphorylase controls the rate of glycogenolysis.
Other metabolic processes, such as lipogenesis, lipolysis, cholesterol synthesis, and ketogenesis, also have rate-determining enzymes. Acetyl-CoA carboxylase controls the rate of lipogenesis, while carnitine-palmitoyl transferase I controls the rate of lipolysis. HMG-CoA reductase is the rate-determining enzyme in cholesterol synthesis, while HMG-CoA synthase controls the rate of ketogenesis.
The urea cycle, de novo pyrimidine synthesis, and de novo purine synthesis also have rate-determining enzymes. Carbamoyl phosphate synthetase I controls the rate of the urea cycle, while carbamoyl phosphate synthetase II controls the rate of de novo pyrimidine synthesis. Glutamine-PRPP amidotransferase is the rate-determining enzyme in de novo purine synthesis.
Understanding the rate-determining enzymes in metabolic processes is crucial for developing treatments for metabolic disorders and diseases. By targeting these enzymes, researchers can potentially regulate the rate of the process and improve the health outcomes of individuals with these conditions.
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This question is part of the following fields:
- General Principles
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Question 34
Correct
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A 32-year-old woman gave birth to a healthy baby at 39+2 through vaginal delivery without any complications. Although she was determined to breastfeed, she is struggling to get her baby to latch on. What is the hormone responsible for stimulating milk production in the breast's alveolar epithelial cells?
Your Answer: Prolactin
Explanation:The process of preparing for lactation involves the hormones oestrogen, progesterone, and human placental lactogen. Oestrogen promotes the development of ducts, while high levels of progesterone stimulate the formation of lobules. Human placental lactogen prepares the mammary glands for lactation.
The two hormones responsible for stimulating lactation are prolactin and oxytocin. Prolactin stimulates milk production, while oxytocin causes the contraction of myoepithelial cells surrounding the mammary alveoli, resulting in milk ejection from the breast.
When the baby suckles, the mechanoreceptors in the nipple are stimulated, leading to the release of both prolactin and oxytocin from the anterior and posterior parts of the pituitary gland, respectively.
Endocrine Changes During Pregnancy
During pregnancy, there are several physiological changes that occur in the body, including endocrine changes. Progesterone, which is produced by the fallopian tubes during the first two weeks of pregnancy, stimulates the secretion of nutrients required by the zygote/blastocyst. At six weeks, the placenta takes over the production of progesterone, which inhibits uterine contractions by decreasing sensitivity to oxytocin and inhibiting the production of prostaglandins. Progesterone also stimulates the development of lobules and alveoli.
Oestrogen, specifically oestriol, is another major hormone produced during pregnancy. It stimulates the growth of the myometrium and the ductal system of the breasts. Prolactin, which increases during pregnancy, initiates and maintains milk secretion of the mammary gland. It is essential for the expression of the mammotropic effects of oestrogen and progesterone. However, oestrogen and progesterone directly antagonize the stimulating effects of prolactin on milk synthesis.
Human chorionic gonadotropin (hCG) is secreted by the syncitiotrophoblast and can be detected within nine days of pregnancy. It mimics LH, rescuing the corpus luteum from degenerating and ensuring early oestrogen and progesterone secretion. It also stimulates the production of relaxin and may inhibit contractions induced by oxytocin. Other hormones produced during pregnancy include relaxin, which suppresses myometrial contractions and relaxes the pelvic ligaments and pubic symphysis, and human placental lactogen (hPL), which has lactogenic actions and enhances protein metabolism while antagonizing insulin.
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This question is part of the following fields:
- Reproductive System
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Question 35
Incorrect
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Which of the following drug/receptor interactions accurately describes steroid hormones?
Your Answer: Fludrocortisone - Mineralocorticoid antagonist
Correct Answer: Tamoxifen – Oestrogen antagonist
Explanation:Examples of Agonist and Antagonist Hormones
Agonist and antagonist hormones are two types of hormones that have opposite effects on the body. Agonist hormones bind to specific receptors in the body and activate them, while antagonist hormones bind to the same receptors but block their activation. This can have a variety of effects on the body, depending on the specific hormone and receptor involved.
Examples of agonist hormones include glucocorticoids like prednisolone, dexamethasone, and hydrocortisone, which are used to treat inflammation and autoimmune disorders. These hormones bind to glucocorticoid receptors and activate them, reducing inflammation and suppressing the immune system.
On the other hand, mifepristone is an antagonist hormone that blocks the effects of glucocorticoids. It is used to terminate pregnancies and to treat conditions like Cushing’s syndrome, which is caused by an excess of glucocorticoids in the body.
Another example of an agonist hormone is fludrocortisone, a mineralocorticoid that is used to treat conditions like Addison’s disease, which is caused by a deficiency of mineralocorticoids. Fludrocortisone binds to mineralocorticoid receptors and activates them, helping to regulate salt and water balance in the body.
In contrast, spironolactone is an antagonist hormone that blocks the effects of mineralocorticoids. It is used to treat conditions like high blood pressure and heart failure, which can be caused by excess mineralocorticoid activity.
Other examples of agonist and antagonist hormones include oestrogen and tamoxifen, which are used to treat breast cancer, and progesterone and danazol, which are used to treat menstrual disorders and endometriosis. the effects of these hormones and their receptors is important for developing effective treatments for a variety of conditions.
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This question is part of the following fields:
- Pharmacology
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Question 36
Incorrect
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A 68-year-old man presents to the orthopaedic outpatient clinic 8 weeks after his hip replacement surgery. His medical records indicate that he underwent a left hip arthroplasty with a posterior approach. He reports feeling generally well, but complains of lower back pain.
During gait examination, the patient displays a left-sided gluteal lurch upon heel strike and exhibits a loss of hip extension on the same side. Based on these findings, which nerve is most likely affected?Your Answer: Superior gluteal nerve
Correct Answer: Inferior gluteal nerve
Explanation:The inferior gluteal nerve innervates the gluteus maximus muscle, while the superior gluteal nerve innervates the gluteus medius and gluteus minimus muscles. The sural nerve provides only sensory innervation to the lateral foot and posterolateral leg, with no motor function.
The gluteal region is composed of various muscles and nerves that play a crucial role in hip movement and stability. The gluteal muscles, including the gluteus maximus, medius, and minimis, extend and abduct the hip joint. Meanwhile, the deep lateral hip rotators, such as the piriformis, gemelli, obturator internus, and quadratus femoris, rotate the hip joint externally.
The nerves that innervate the gluteal muscles are the superior and inferior gluteal nerves. The superior gluteal nerve controls the gluteus medius, gluteus minimis, and tensor fascia lata muscles, while the inferior gluteal nerve controls the gluteus maximus muscle.
If the superior gluteal nerve is damaged, it can result in a Trendelenburg gait, where the patient is unable to abduct the thigh at the hip joint. This weakness causes the pelvis to tilt down on the opposite side during the stance phase, leading to compensatory movements such as trunk lurching to maintain a level pelvis throughout the gait cycle. As a result, the pelvis sags on the opposite side of the lesioned superior gluteal nerve.
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This question is part of the following fields:
- Neurological System
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Question 37
Incorrect
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A 32-year-old construction worker presents to the doctor with a cough and profuse watery diarrhoea that has been ongoing for a week. He also reports experiencing regular fevers and vomiting. The patient mentions that three of his colleagues have also been affected by a similar illness. Upon examination, he appears dehydrated and has a heart rate of 110 beats per minute. A Cryptosporidium infection is confirmed through a stool sample. What stain would be used to confirm this diagnosis?
Your Answer: Gram stain
Correct Answer: Ziehl-Neelsen stain
Explanation:The diagnosis of Cryptosporidium can be made using a modified approach.
Understanding Cryptosporidiosis
Cryptosporidiosis is a prevalent cause of diarrhoea in the UK, caused by two species of Cryptosporidium – C. hominis and C. parvum. This condition is more common in young children and immunocompromised patients, such as those with HIV. Symptoms include watery diarrhoea, abdominal cramps, and fever. In severe cases, the entire gastrointestinal tract may be affected, leading to complications like sclerosing cholangitis and pancreatitis.
To diagnose cryptosporidiosis, a modified Ziehl-Neelsen stain (acid-fast stain) of the stool may reveal the characteristic red cysts of Cryptosporidium. Management for immunocompetent patients is largely supportive, while antiretroviral therapy is recommended for HIV patients. Nitazoxanide may be used for immunocompromised patients, and rifaximin is sometimes used for those with severe disease.
Overall, understanding cryptosporidiosis is crucial for prompt diagnosis and management, especially in vulnerable populations.
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This question is part of the following fields:
- General Principles
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Question 38
Correct
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A 49-year-old female presents to her family physician with complaints of post-coital pain. She initially attributed it to her age, but lately, she has been experiencing a constant dull pain in her pelvis. Additionally, she reports having a foul-smelling discharge from her vagina. Her medical and surgical history is unremarkable, but she mentions having multiple sexual partners during her teenage years and twenties. She has been smoking ten cigarettes a day for the past decade and does not consume alcohol. During the examination, the doctor discovers an irregular mass on her cervix. What is the primary mechanism behind the most significant risk factor for this patient's condition?
Your Answer: Human papillomavirus 16 and 18 produces oncoproteins which causes inhibition of the tumor suppressor genes causing cervical carcinoma
Explanation:The patient is displaying typical signs and symptoms of cervical carcinoma, with a constant dull pelvic pain indicating possible invasion of pelvic structures and nerves. The strongest risk factor for this patient is having had multiple sexual partners at a young age, which increases the likelihood of being infected with the human papillomavirus.
1: Multiple sexual partners are the strongest risk factor for cervical carcinoma due to the increased chance of contracting the human papillomavirus, specifically the 16 and 18 viral strains that inhibit the tumor suppressor genes p53 and RB, triggering carcinogenesis.
2: While cigarette smoking can have an oncogenic effect, it is not the primary risk factor in this case.
3: HIV is a risk factor for cervical carcinoma, but it is less common than the human papillomavirus.
4: The human papillomavirus is the primary risk factor, but it does not activate oncogenes. Instead, it inhibits tumor suppressor genes.
5: Age alone is not a risk factor for cervical carcinoma. However, an older person who has been exposed to the human papillomavirus may have a higher risk due to the longer exposure time for the virus to induce carcinogenesis via the inhibition of tumor suppressor genes.HPV Infection and Cervical Cancer
Human papillomavirus (HPV) infection is the primary risk factor for cervical cancer, with subtypes 16, 18, and 33 being the most carcinogenic. Other common subtypes, such as 6 and 11, are associated with genital warts but are not carcinogenic. When endocervical cells become infected with HPV, they may undergo changes that lead to the development of koilocytes. These cells have distinct characteristics, including an enlarged nucleus, irregular nuclear membrane contour, hyperchromasia (darker staining of the nucleus), and a perinuclear halo. These changes are important diagnostic markers for cervical cancer and can be detected through Pap smears or other screening methods. Early detection and treatment of HPV infection and cervical cancer can greatly improve outcomes and reduce the risk of complications.
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This question is part of the following fields:
- Haematology And Oncology
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Question 39
Correct
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A 70-year-old man is recuperating from a fall that resulted in a fracture of his left fibular neck. He has observed that his left foot drags on the ground when he attempts to walk. Which nerve is the most probable to have been affected?
Your Answer: Common peroneal nerve
Explanation:The patient is likely to have suffered damage to their common peroneal nerve, resulting in foot drop, following a fibular neck fracture. This is a common occurrence in such cases.
It is important to note that damage to the lateral cutaneous nerve of the thigh, obturator nerve, or pudendal nerve is unlikely to cause foot drop. These nerves are associated with different symptoms and conditions.
Lower limb anatomy is an important topic that often appears in examinations. One aspect of this topic is the nerves that control motor and sensory functions in the lower limb. The femoral nerve controls knee extension and thigh flexion, and provides sensation to the anterior and medial aspect of the thigh and lower leg. It is commonly injured in cases of hip and pelvic fractures, as well as stab or gunshot wounds. The obturator nerve controls thigh adduction and provides sensation to the medial thigh. It can be injured in cases of anterior hip dislocation. The lateral cutaneous nerve of the thigh provides sensory function to the lateral and posterior surfaces of the thigh, and can be compressed near the ASIS, resulting in a condition called meralgia paraesthetica. The tibial nerve controls foot plantarflexion and inversion, and provides sensation to the sole of the foot. It is not commonly injured as it is deep and well protected, but can be affected by popliteral lacerations or posterior knee dislocation. The common peroneal nerve controls foot dorsiflexion and eversion, and can be injured at the neck of the fibula, resulting in foot drop. The superior gluteal nerve controls hip abduction and can be injured in cases of misplaced intramuscular injection, hip surgery, pelvic fracture, or posterior hip dislocation. Injury to this nerve can result in a positive Trendelenburg sign. The inferior gluteal nerve controls hip extension and lateral rotation, and is generally injured in association with the sciatic nerve. Injury to this nerve can result in difficulty rising from a seated position, as well as difficulty jumping or climbing stairs.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 40
Incorrect
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You are in a nutrition clinic reviewing a 16-year-old boy with anorexia nervosa. He has a BMI of 15.5 kg/m2 and his weight is 70% the expected weight for height.
How would you classify his level of malnutrition?Your Answer: Moderate undernutrition
Correct Answer: Severe undernutrition
Explanation:Malnutrition
Malnutrition is a clinical condition that occurs when there is an imbalance in the energy, protein, or other components of the diet, leading to adverse effects on the body’s health. This condition encompasses undernutrition, overnutrition, and vitamin and mineral deficiencies. Undernutrition is the most common form of malnutrition and is classified based on different grading systems used worldwide. Severe undernutrition is characterized by a weight of less than 70-75% of the expected weight for age and a BMI of less than 16 kg/m2.
To grade the severity of protein-energy malnutrition (PEM), a scale is commonly used. This scale considers the expected weight for age and BMI. A normal weight is between 90-110% of the expected weight for age and a BMI of 19-24 kg/m2. Mild undernutrition is between 85-90% of the expected weight for age and a BMI of 18-18.9 kg/m2. Moderate undernutrition is between 75-85% of the expected weight for age and a BMI of 16-17.9 kg/m2. Severe undernutrition is less than 75% of the expected weight for age and a BMI of less than 16 kg/m2.
In summary, malnutrition is a serious condition that affects many people worldwide. the different types of malnutrition and their severity can help healthcare professionals provide appropriate treatment and interventions to improve the health outcomes of those affected.
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This question is part of the following fields:
- Clinical Sciences
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