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Question 1
Incorrect
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Which of the following statements is correct regarding the lymphatic system?
Your Answer: The lymphatic system empties into the thoracic duct, which in turn empties into the jugular vein.
Correct Answer: Lymphatic vessels contain both smooth muscle and unidirectional valves.
Explanation:Fluid filtration out of the capillaries is usually slightly greater than fluid absorption into the capillaries. About 8 L of fluid per day is filtered by the microcirculation and returns to the circulation by the lymphatic system. Lymphatic capillaries drain into collecting lymphatics, then into larger lymphatic vessels. Both of these containing smooth muscle and unidirectional valves. From this point, lymph is propelled by smooth muscle constriction and vessel compression by body movements into afferent lymphatics. It then goes to the lymph nodes where phagocytes remove bacteria and foreign materials. It is here that most fluid is reabsorbed by capillaries, and the remainder returns to the subclavian veins via efferent lymphatics and the thoracic duct. The lymphatic system has a major role to play in the body’s immune defence and also has a very important role in the absorption and transportation of fats.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 2
Incorrect
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An 82 year old man taking warfarin as a maintenance medication comes in to your clinic because of an infection. Which antibiotic is the safest choice for this patient?
Your Answer: Ciprofloxacin
Correct Answer: Cefalexin
Explanation:Alterations in the international normalized ratio (INR) brought about by the concurrent use of antibiotics and warfarin may result in either excessive clotting or excessive bleeding if they are deemed to have a high risk for interaction. As such, there should be careful consideration of the class of antibiotic to be used.
Antibiotics from the following drug classes should generally be avoided as they have a high risk for interaction with warfarin, possible enhancing the anticoagulant effects of warfarin resulting in bleeding: Fluoroquinolones (e.g. ciprofloxacin, levofloxacin), Macrolides (e.g. clarithromycin, erythromycin, azithromycin), Nitroimidazoles (e.g. metronidazole), Sulphonamides (e.g. co-trimoxazole, a combination of trimethoprim and sulfamethoxazole), Trimethoprim, Tetracyclines (e.g. doxycycline).
Low risk antibiotics that have low risk for interaction with warfarin includes cephalexin, from the cephalosporin class, and clindamycin which is a lincomycin.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 3
Incorrect
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In ventricular myocytes, the plateau phase of the action potential comes about through which of the following:
Your Answer: Closing of voltage-gated Na + channels
Correct Answer: Opening of voltage-gated Ca 2+ channels
Explanation:After the intial upstroke of the action potential, Na+channels and currents rapidly inactivate, but in cardiac myocytes, the initial depolarisation activates voltage-gated Ca2+channels (slow L-type channels, threshold approximately – 45 mV) through which Ca2+floods into the cell. The resulting influx of Ca2+prevents the cell from repolarising and causes a plateau phase, that is maintained for about 250 ms until the L-type channels inactivate. The cardiac AP is thus much longer than that in nerve or skeletal muscle.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 4
Incorrect
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Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT:
Your Answer: Factors that affect intracellular [Ca 2+ ] and hence cardiac contractility are called chronotropes.
Correct Answer: In relaxation, Ca 2+ is transported out of the cell using energy from a Na + gradient.
Explanation:During the AP plateau, Ca2+enters the cell and activates Ca2+sensitive Ca2+release channels in the sarcoplasmic reticulum allowing stored Ca2+to flood into the cytosol; this is called Ca2+-induced Ca2+release. In relaxation, about 80% of Ca2+is rapidly pumped back into the SR (sequestered) by Ca2+ATPase pumps. The Ca2+that entered the cell during the AP is transported out of the cell primarily by the Na+/Ca2+exchanger in the membrane which pumps one Ca2+ion out in exchange for three Na+ions in, using the Na+electrochemical gradient as an energy source. Increased heart rate increases the force of contraction in a stepwise fashion as intracellular [Ca2+] increases cumulatively over several beats; this is the Treppe effect. Factors that affect intracellular [Ca2+] and hence cardiac contractility are called inotropes.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 5
Incorrect
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Which of the following does NOT predispose to digoxin toxicity in a patient taking digoxin:
Your Answer: Hypokalaemia
Correct Answer: Hyponatraemia
Explanation:Hypoxia, hypercalcaemia, hypokalaemia and hypomagnesaemia predispose to digoxin toxicity. Care should also be taken in the elderly who are particularly susceptible to digoxin toxicity. Hypokalaemia may be precipitated by use of diuretics. Although hyponatremia can result in the development of other pathological disturbances, it does not potentiate digoxin toxicity.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 6
Correct
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Which of the following drug classes may cause bronchoconstriction:
Your Answer: Beta-blockers
Explanation:Beta-blockers, including those considered to be cardioselective, should usually be avoided in patients with a history of asthma, bronchospasm or a history of obstructive airways disease. However, when there is no alternative, a cardioselective beta-blocker can be given to these patients with caution and under specialist supervision. In such cases the risk of inducing bronchospasm should be appreciated and appropriate precautions taken.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 7
Incorrect
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Regarding alteplase, which of the following statements is INCORRECT:
Your Answer: Alteplase must be given by continuous intravenous infusion.
Correct Answer: Alteplase is commonly associated with hypotensive effects.
Explanation:Alteplase is a recombinant tissue-type plasminogen activator (tPA), a naturally occurring fibrin-specific enzyme that has selectivity for activation of fibrin-bound plasminogen. It has a short half-life of 3 – 4 minutes and must be given by continuous intravenous infusion but is not associated with antigenic or hypotensive effects, and can be used in patients when recent streptococcal infections or recent use of streptokinase contraindicates the use of streptokinase.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 8
Incorrect
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A patient who is taking ramipril for high blood pressure complains of a dry persistent cough. What is the mechanism of cough in ACE inhibitor therapy:
Your Answer: Increased histamine release
Correct Answer: Decreased bradykinin breakdown
Explanation:Blocking ACE also diminishes the breakdown of the potent vasodilator bradykinin which is the cause of the persistent dry cough. Angiotensin-II receptor blockers do not have this effect, therefore they are useful alternative for patients who have to discontinue an ACE inhibitor because of persistent cough.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 9
Correct
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In the treatment of hypertensive episodes in pheochromocytoma, which of the following medication types is administered as first-line management:
Your Answer: Alpha-blockers
Explanation:The first line of management in controlling blood pressure and preventing intraoperative hypertensive crises is to use a combination of alpha and beta-adrenergic inhibition. In phaeochromocytoma, alpha-blockers are used to treat hypertensive episodes in the short term. Tachycardia can be managed by the careful addition of a beta-blocker, preferably a cardioselective beta-blocker, once alpha blockade has been established. Long term management of pheochromocytoma involves surgery.
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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Question 10
Incorrect
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Digoxin is contraindicated in all of the following EXCEPT for:
Your Answer: Ventricular tachycardia
Correct Answer: Asthma
Explanation:Digoxin is contraindicated in:Supraventricular arrhythmias associated with accessory conduction pathways e.g. Wolff-Parkinson-White syndromeVentricular tachycardia or fibrillationHeart conduction problems e.g. second degree or intermittent complete heart blockHypertrophic cardiomyopathy (unless concomitant atrial fibrillation and heart failure but should be used with caution)
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This question is part of the following fields:
- Cardiovascular
- Pharmacology
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SESSION STATS - PERFORMANCE PER SPECIALTY
