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Question 1
Correct
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For the treatment of his atrial fibrillation, a 67-year-old man is about to begin taking warfarin. He also takes a number of other medications.
Which of the following medications will prevent warfarin from working?Your Answer: Phenytoin
Explanation:Many medications, including warfarin, require cytochrome P450 enzymes for their metabolism. When co-prescribing cytochrome p450 enzyme inducers and inhibitors with warfarin, it’s critical to be cautious.
Inhibitors of the cytochrome p450 enzyme inhibit the effects of warfarin, resulting in a lower INR. To remember the most commonly encountered cytochrome p450 enzyme inducers, use the mnemonic PC BRASS:
P– Phenytoin
C– Carbamazepine
B– Barbiturates
R– Rifampicin
A– Alcohol (chronic ingestion)
S– Sulphonylureas
S– Smoking -
This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 2
Incorrect
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Regarding chemical control of respiration, which of the following statements is INCORRECT:
Your Answer: There is a synergistic relationship between PO2 and PCO2 in stimulating ventilatory response.
Correct Answer: The blood-brain barrier is freely permeable to HCO3 - ions.
Explanation:CSF is separated from the blood by the blood-brain barrier. This barrier is impermeable to polar molecules such as H+and HCO3-but CO2can diffuse across it easily. The pH of CSF is therefore determined by the arterial PCO2and the CSF HCO3-and is not affected by blood pH.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 3
Correct
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Swelling of the lips, tongue, and face is observed in a 59-year-old African-American woman. In the emergency room, she is given intramuscular adrenaline, but her symptoms do not improve. Her GP recently started her on a new medication.
Which of the following drugs is most likely to have caused her symptoms?Your Answer: Ramipril
Explanation:Angiotensin-converting enzyme (ACE) inhibitors are the most common cause of drug-induced angioedema in the United Kingdom and the United States, owing to their widespread use.
Angioedema is caused by ACE inhibitors in 0.1 to 0.7 percent of patients, with data indicating a persistent and relatively constant risk year after year. People of African descent have a five-fold higher chance of contracting the disease.
Swelling of the lips, tongue, or face is the most common symptom, but another symptom is episodic abdominal pain due to intestinal angioedema. Itching and urticaria are noticeably absent.
The mechanism appears to be activated complement or other pro-inflammatory cytokines like prostaglandins and histamine, which cause rapid vasodilation and oedema.
Other medications that are less frequently linked to angioedema include:
Angiotensin-receptor blockers (ARBs)
Nonsteroidal anti-inflammatory drugs (NSAIDs)
Bupropion (e.g. Zyban and Wellbutrin)
Beta-lactam antibiotics
Statins
Proton pump inhibitorsThe majority of these reactions are minor and can be treated by stopping the drug and prescribing antihistamines.
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This question is part of the following fields:
- Cardiovascular Pharmacology
- Pharmacology
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Question 4
Incorrect
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Which of the following clinical features is a feature of a chronic extravascular haemolytic anaemia:
Your Answer:
Correct Answer: Gallstones
Explanation:Clinical features of haemolytic anaemia include:
Anaemia
Jaundice (caused by unconjugated bilirubin in plasma, bilirubin is absent from urine)
Pigment gallstones
Splenomegaly
Ankle ulcers
Expansion of marrow with, in children, bone expansion e.g. frontal bossing in beta-thalassaemia major
Aplastic crisis caused by parvovirus -
This question is part of the following fields:
- Haematology
- Pathology
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Question 5
Incorrect
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The cutaneous circulation is responsible for the skin's blood supply. Because the skin is not a highly metabolically active tissue with low energy requirements, its blood supply differs from that of other tissues. Instead of capillaries, some of the circulating blood volume in the skin passes through arteriovenous anastomoses (AVAs).
Which of the following statements regarding arteriovenous anastomoses is correct?
Your Answer:
Correct Answer: AVAs are innervated by sympathetic fibres originating from the hypothalamus
Explanation:Short vessels called arteriovenous anastomoses (AVAs) link tiny arteries and veins. They have a large lumen diameter. The strong and muscular walls allow AVAs to completely clog the vascular lumen, preventing blood flow from artery to vein (acting like a sphincter). When the AVAs open, they create a low-resistance connection between arteries and veins, allowing blood to flow into the limbs’ superficial venous plexuses. There is no diffusion of solutes or fluid into the interstitium due to their strong muscle walls.
AVAs are densely innervated by adrenergic fibres from the hypothalamic temperature-regulation centre. High sympathetic output occurs at normal core temperatures, inducing vasoconstriction of the AVAs and blood flow through the capillary networks and deep plexuses. When the temperature rises, sympathetic output decreases, producing AVA vasodilation and blood shunting from the artery to the superficial venous plexus. Heat is lost to the environment as hot blood rushes near to the skin’s surface.
AVAs are a specialized anatomical adaptation that can only be found in large quantities in the fingers, palms, soles, lips, and pinna of the ear. -
This question is part of the following fields:
- Cardiovascular Physiology
- Physiology
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Question 6
Incorrect
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A 78-year-old male presents to the Orthopaedic clinic with lower back pain for the past month. His past medical history reveals a history of cancer. After examination, you diagnose Metastatic Spinal Cord Compression (MSCC).
Which one of the following cancers is this patient most likely to have had?Your Answer:
Correct Answer: Prostate cancer
Explanation:Compression of the thecal sac causes metastatic Spinal Cord Compression (MSCC) due to a Metastatic tumour and its components. It can cause symptoms of limb weakness, sensory disturbances and back pain depending on the extent and level of Compression.
The most common source of a tumour causing MSCC is a prostate carcinoma that metastasized to the spinal cord via the vertebral venous plexus.
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 7
Incorrect
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All of the following are indications for beta-blockers EXCEPT for:
Your Answer:
Correct Answer: Raynaud's disease
Explanation:Beta-blockers are contraindicated in Raynaud’s syndrome.
Beta-blockers may be indicated in:
Hypertension
Pheochromocytoma (only with an alpha-blocker)
Angina
Secondary prevention after ACS
Arrhythmias including atrial fibrillation
Heart failure
Thyrotoxicosis
Anxiety
Prophylaxis of migraine
Essential tremor
Glaucoma -
This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 8
Incorrect
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A young farmer who is caught under farm machinery and suffering from a major crush injury is taken to the emergency department and requires a quick induction sequence. In this type of injury, which of the following anaesthetic medicines should be avoided?
Your Answer:
Correct Answer: Suxamethonium
Explanation:Suxamethonium is a neuromuscular blocker. It is contraindicated in patients who have experienced massive trauma, hyperkalemic, or burn injuries.
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This question is part of the following fields:
- Anaesthesia
- Pharmacology
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Question 9
Incorrect
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A 2-day-old male is referred to a tertiary care hospital by the community midwife after a home visit due to jaundice and dyspnoea. After history and examination, the relevant blood work is performed, and the baby is found to have conjugated hyperbilirubinemia. The paediatric team suspects a hepatic origin for jaundice based on the findings.
Which one of the following aetiologies is the most likely cause of jaundice in this case?Your Answer:
Correct Answer: Alpha 1-antitrypsin deficiency
Explanation:The presence of dyspnoea makes alpha-1 antitrypsin deficiency the more likely diagnosis as biliary atresia does not cause respiratory symptoms. Deficiency of the enzyme alpha-1 antitrypsin causes uninhibited elastase activity and a decrease in elastic tissue. This causes liver cirrhosis leading to an elevation of conjugated bilirubin and emphysema in the lungs.
Rhesus disease, hereditary spherocytosis and breast milk jaundice cause an elevation of unconjugated bilirubin thus ruling it out in this case. Breast milk jaundice occurs due to an inability of the newborn to metabolize the proteins in breast milk.
Rhesus disease occurs when an Rh negative mother gives birth to an Rh positive baby. The jaundice would have been accompanied by anaemia and oedema.
Hereditary spherocytosis occurs due to extravascular haemolysis as defective RBCs are removed by the spleen. The patient would present with jaundice, splenomegaly and possibly an aplastic crisis (if Parvovirus B19 infection).
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This question is part of the following fields:
- General Pathology
- Pathology
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Question 10
Incorrect
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For an action potential to occur, which of the following must be true:
Your Answer:
Correct Answer: Depolarisation of the membrane must reach threshold potential
Explanation:For an action potential to occur, the membrane must become more permeable to Na+and the Na+influx must be greater than the K+efflux. An action potential occurs when depolarisation of the membrane reaches threshold potential. The membrane must be out of the absolute refractory period, however an action potential can still occur in a relative refractory period but only in response to a larger than normal stimulus.
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This question is part of the following fields:
- Basic Cellular
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
