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  • Question 1 - In ventricular myocytes, the plateau phase of the action potential comes about through which...

    Incorrect

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      3
      Seconds

  • Question 2 - At the start of the cardiac cycle, towards the end of diastole, all...

    Incorrect

    • At the start of the cardiac cycle, towards the end of diastole, all of the following statements are true EXCEPT for:

      Your Answer:

      Correct Answer: The semilunar valves are open.

      Explanation:

      At the start of the cardiac cycle, towards the end of diastole, the whole of the heart is relaxed. The atrioventricular (AV) valves are open because the atrial pressure is still slightly greater than the ventricular pressure. The semilunar valves are closed, as the pressure in the pulmonary artery and aorta is greater than the ventricular pressures. The cycle starts when the sinoatrial node (SAN) initiates atrial systole.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 3 - As a response to low blood pressure, the baroreceptor reflex will facilitate vasoconstriction...

    Incorrect

    • As a response to low blood pressure, the baroreceptor reflex will facilitate vasoconstriction by activating which receptor?

      Your Answer:

      Correct Answer: Alpha1

      Explanation:

      The rate of baroreceptor firing slows down when blood pressure falls too low. This causes an increase in sympathetic stimulation of the heart, resulting in an increase in cardiac output. It also causes vasoconstriction by activating alpha 1 receptors in smooth muscle, which causes sympathetic stimulation of peripheral vessels.

      Alpha2 receptors can be found in both the brain and the peripheral nervous system. They control sympathetic outflow in the brain stem.

      Beta1 receptors, which are found on the cell membrane of cardiac muscle cells, stimulate heart rate and myocardial contractility. The smooth muscle cell membrane contains beta2 receptors, which promote smooth muscle relaxation in the lungs causing bronchodilation, GI tract, and peripheral blood vessels.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 4 - What is the main mechanism of action of dobutamine as an inotropic sympathomimetic:...

    Incorrect

    • What is the main mechanism of action of dobutamine as an inotropic sympathomimetic:

      Your Answer:

      Correct Answer: Beta1-receptor agonist

      Explanation:

      Dobutamine directly stimulates the beta1-adrenergic receptors in the heart and increases contractility and cardiac output with little effect on the rate. In addition action on beta2-receptors causes vasodilation.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 5 - Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT: ...

    Incorrect

    • Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT:

      Your Answer:

      Correct Answer: The Treppe effect refers to an increase in contractility secondary to an increase in heart rate.

      Explanation:

      Although Ca2+entry during the action potential (AP) is essential for contraction, it only accounts for about 25% of the rise in intracellular Ca2+. The rest is released from Ca2+stores in the sarcoplasmic reticulum (SR). 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. When more action potentials occur per unit time, more Ca2+enters the cell during the AP plateau, more Ca2+is stored in the SR, more Ca2+is released from the SR and thus more Ca2+is left inside the cell and greater tension is produced during contraction. 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. Cardiac glycosides such as digoxin have a positive inotropic effect.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 6 - By which of the following is mean arterial pressure (MAP) primarily determined? ...

    Incorrect

    • By which of the following is mean arterial pressure (MAP) primarily determined?

      Your Answer:

      Correct Answer: Total peripheral resistance and cardiac output

      Explanation:

      Mean arterial pressure (MAP) = Cardiac output (CO) x Total peripheral resistance (TPR).

      Cardiac output is dependent on the central venous pressure (CVP). CVP, in turn, is highly dependent on the blood volume.
      Any alterations of any of these variables will likely change MAP.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 7 - All of the following are indications for beta-blockers EXCEPT for: ...

    Incorrect

    • 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
      0
      Seconds

  • Question 8 - Adenosine has a half-life of approximately: ...

    Incorrect

    • Adenosine has a half-life of approximately:

      Your Answer:

      Correct Answer: 8 - 10 seconds

      Explanation:

      Adenosine stimulates A1-adenosine receptors and opens acetylcholine sensitive K+ channels, increasing K+ efflux. This hyperpolarises the cell membrane in the atrioventricular node and, by inhibiting the calcium channels, slows conduction in the AVN. As it has a very short duration of action (half-life only about 8 – 10 seconds), most side effects are short lived.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 9 - Mannitol is primarily indicated for which of the following: ...

    Incorrect

    • Mannitol is primarily indicated for which of the following:

      Your Answer:

      Correct Answer: Cerebral oedema

      Explanation:

      Mannitol is an osmotic diuretic that can be used to treat cerebral oedema and raised intraocular pressure. Mannitol is a low molecular weight compound and is, therefore, freely filtered at the glomerulus and is not reabsorbed. It, therefore, increases the osmolality of the glomerular filtrate and tubular fluid, increasing urinary volume by an osmotic effect. It also does not cross the blood-brain-barrier (BBB).

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 10 - When an elderly dehydrated patient is moved from a supine to a standing...

    Incorrect

    • When an elderly dehydrated patient is moved from a supine to a standing position, her heart rate increases. Which of the following accounts for the increase in heart rate upon standing:

      Your Answer:

      Correct Answer: Decreased venous return

      Explanation:

      On standing from a prone position, gravity causes blood to pool in veins in the legs. Central venous pressure (CVP) falls, causing a fall in stroke volume and cardiac output (due to Starling’s law) and thus a fall in blood pressure. Normally this fall in BP is rapidly corrected by the baroreceptor reflex which causes venoconstriction (partially restoring CVP), and an increase in heart rate and contractility, so restoring cardiac output and blood pressure. Impaired autonomic nervous activity in the elderly accounts for the greater likelihood of postural hypotension. Any symptoms of dizziness, blurred vision or syncope is due to a transient fall in cerebral perfusion that occurs before cardiac output and mean arterial pressure (MAP) can be corrected.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 11 - What is the primary mode of action of Enoxaparin? ...

    Incorrect

    • What is the primary mode of action of Enoxaparin?

      Your Answer:

      Correct Answer: Inhibits factor Xa

      Explanation:

      Heparin acts as an anticoagulant by enhancing the inhibition rate of clotting proteases by antithrombin III impairing normal haemostasis and inhibition of factor Xa. Low molecular weight heparins have a small effect on the activated partial thromboplastin time and strongly inhibit factor Xa. Enoxaparin is derived from porcine heparin that undergoes benzylation followed by alkaline depolymerization.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 12 - For a tachyarrhythmia caused by shock, which of the following is the first-line...

    Incorrect

    • For a tachyarrhythmia caused by shock, which of the following is the first-line treatment:

      Your Answer:

      Correct Answer: Synchronised DC shock

      Explanation:

      If there are any adverse symptoms, immediate cardioversion with synchronized DC shock is recommended. If cardioversion fails to stop the arrhythmia and the symptoms persist, amiodarone 300 mg IV over 10–20 minutes should be administered before attempting another cardioversion. The loading dosage of amiodarone is followed by a 24-hour infusion of 900 mg administered into a large vein.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 13 - Bendoflumethiazide may cause all of the following electrolyte imbalances EXCEPT for: ...

    Incorrect

    • Bendoflumethiazide may cause all of the following electrolyte imbalances EXCEPT for:

      Your Answer:

      Correct Answer: Hypocalcaemia

      Explanation:

      Common side effects of thiazide diuretics include:
      Excessive diuresis, postural hypotension, dehydration, renal impairment
      Acid-base and electrolyte imbalance
      Hypokalaemia, hyponatraemia, hypomagnesaemia, hypercalcaemia, hypochloraemic alkalosis
      Metabolic imbalance
      Hyperuricaemia and gout
      Impaired glucose tolerance and hyperglycaemia
      Altered plasma-lipid concentrations
      Mild gastrointestinal disturbances

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 14 - Which of the following is NOT an adverse effect associated with warfarin therapy:...

    Incorrect

    • Which of the following is NOT an adverse effect associated with warfarin therapy:

      Your Answer:

      Correct Answer: Neutropenia

      Explanation:

      Adverse effects of warfarin:
      The most common adverse effect of warfarin is bleeding

      Other common adverse effects of warfarin include nausea, vomiting, diarrhoea, jaundice, hepatic dysfunction, pancreatitis, pyrexia, alopecia, purpura, and rash

      Skin necrosis is a rare but serious adverse effect of warfarin; treatment with warfarin should be stopped if warfarin related skin necrosis is suspected

      Calciphylaxis is a rare, but a very serious condition that causes vascular calcification and cutaneous necrosis

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 15 - Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT: ...

    Incorrect

    • Regarding cardiac excitation-contraction coupling, which of the following statements is CORRECT:

      Your Answer:

      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.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 16 - What is the main mechanism of action of flecainide: ...

    Incorrect

    • What is the main mechanism of action of flecainide:

      Your Answer:

      Correct Answer: Blocks Na+ channels

      Explanation:

      Flecainide inhibits the transmembrane influx of extracellular Na+ ions via fast channels on cardiac tissues resulting in a decrease in rate of depolarisation of the action potential, prolonging the PR and QRS intervals. At high concentrations, it exerts inhibitory effects on slow Ca2+ channels, accompanied by moderate negative inotropic effect.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 17 - What is the most common application of Nitrates? ...

    Incorrect

    • What is the most common application of Nitrates?

      Your Answer:

      Correct Answer: Angina

      Explanation:

      In patients with exertional stable angina, nitrates improve exercise tolerance, time to onset of angina, and ST-segment depression during exercise testing. In combination with beta-blockers or calcium channel blockers, nitrates produce greater anti-anginal and anti-ischemic effects.
      While they act as vasodilators, coronary vasodilators, and modest arteriolar dilators, the primary anti ischemic effect of nitrates is to decrease myocardial oxygen demand by producing systemic vasodilation more than coronary vasodilation. This systemic vasodilation reduces left ventricular systolic wall stress.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 18 - Which of the following describes the pulse pressure: ...

    Incorrect

    • Which of the following describes the pulse pressure:

      Your Answer:

      Correct Answer: Systolic - diastolic pressure

      Explanation:

      During systole, the pressure in the left ventricle increases and blood is ejected into the aorta. The rise in pressure stretches the elastic walls of the aorta and large arteries and drives blood flow. Systolic pressure is the maximum arterial pressure during systole. During diastole, arterial blood flow is partly maintained by elastic recoil of the walls of large arteries. The minimum pressure reached before the next systole is the diastolic pressure. The difference between the systolic and diastolic pressure is the pulse pressure.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 19 - The mechanism of action of abciximab is by: ...

    Incorrect

    • The mechanism of action of abciximab is by:

      Your Answer:

      Correct Answer: Blocking the binding of fibrinogen to GPIIb/IIIa receptor sites

      Explanation:

      Abciximab is a glycoprotein IIb/IIIa inhibitors and prevents platelet aggregation by blocking the binding of fibrinogen to receptors on platelets.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 20 - Which of the following is NOT an adverse effect associated with statin therapy:...

    Incorrect

    • Which of the following is NOT an adverse effect associated with statin therapy:

      Your Answer:

      Correct Answer: Aplastic anaemia

      Explanation:

      Adverse effects of statins include:, Headache, Epistaxis, Gastrointestinal disorders (such as constipation, flatulence, dyspepsia, nausea, and diarrhoea), Musculoskeletal and connective tissue disorders (such as myalgia, arthralgia, pain in the extremity, muscle spasms, joint swelling, and back pain), Hyperglycaemia and diabetes, Myopathy and rhabdomyolysis, Interstitial lung disease and Hepatotoxicity

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 21 - Regarding postural hypotension, which of the following statements is INCORRECT: ...

    Incorrect

    • Regarding postural hypotension, which of the following statements is INCORRECT:

      Your Answer:

      Correct Answer: Postural hypotension usually causes a reflex bradycardia.

      Explanation:

      On standing from a prone position, gravity causes blood to pool in veins in the legs. Central venous pressure (CVP) falls, causing a fall in stroke volume and cardiac output (due to Starling’s law) and thus a fall in blood pressure. Normally this fall in BP is rapidly corrected by the baroreceptor reflex which causes venoconstriction (partially restoring CVP), and an increase in heart rate and contractility, so restoring cardiac output and blood pressure. Impaired autonomic nervous activity in the elderly accounts for the greater likelihood of postural hypotension. Any symptoms of dizziness, blurred vision or syncope is due to a transient fall in cerebral perfusion that occurs before cardiac output and mean arterial pressure (MAP) can be corrected.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 22 - When a person changes from a supine to an upright position, which of...

    Incorrect

    • When a person changes from a supine to an upright position, which of the followingcompensatory mechanismsoccurs:

      Your Answer:

      Correct Answer: Increased contractility

      Explanation:

      On standing from a prone position, gravity causes blood to pool in veins in the legs. Central venous pressure (CVP) falls, causing a fall in stroke volume and cardiac output (due to Starling’s law) and thus a fall in blood pressure. Normally this fall in BP is rapidly corrected by the baroreceptor reflex which causes venoconstriction (partially restoring CVP), and an increase in heart rate and contractility, so restoring cardiac output and blood pressure. Impaired autonomic nervous activity in the elderly accounts for the greater likelihood of postural hypotension. Any symptoms of dizziness, blurred vision or syncope is due to a transient fall in cerebral perfusion that occurs before cardiac output and mean arterial pressure (MAP) can be corrected.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 23 - Digoxin exhibits its positive inotropic effect by which of the following mechanisms: ...

    Incorrect

    • Digoxin exhibits its positive inotropic effect by which of the following mechanisms:

      Your Answer:

      Correct Answer: Inhibits the Na+/K+ pump on the myocyte membrane

      Explanation:

      Cardiac glycosides (e.g. digoxin) slow the removal of Ca2+from the cell by inhibiting the membrane Na+pump (Na+/K+ATPase) which generates the Na+gradient required for driving the export of Ca2+by Na+/Ca2+exchange; consequently the removal of Ca2+from the myocyte is slowed and more Ca2+is available for the next contraction.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 24 - The Frank-Starling curve is shifted downhill in heart failure due to which of...

    Incorrect

    • The Frank-Starling curve is shifted downhill in heart failure due to which of the following?

      Your Answer:

      Correct Answer: Decrease in contractility

      Explanation:

      The Frank–Starling mechanism states that the left ventricle can increase its force of contraction and hence stroke volume in response to increases in venous return and thus preload.

      Changes in afterload or inotropy cause the Frank–Starling curve to rise or fall. In heart failure, the Frank–Starling curve is shifted downward (flattened), requiring higher venous return and filling pressure to enhance contractility and stroke volume.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 25 - Action potentials are transmitted from myocyte to myocyte via which of the following:...

    Incorrect

    • Action potentials are transmitted from myocyte to myocyte via which of the following:

      Your Answer:

      Correct Answer: Gap junctions

      Explanation:

      Action potentials are transmitted to adjacent myocytes via gap junctions.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      0
      Seconds

  • Question 26 - Regarding hypertensive crises, which of the following statements is CORRECT: ...

    Incorrect

    • Regarding hypertensive crises, which of the following statements is CORRECT:

      Your Answer:

      Correct Answer: In a hypertensive emergency, blood pressure should be reduced by 20 - 25% within 2 hours.

      Explanation:

      A hypertensive emergency is defined as severe hypertension (blood pressure ≥ 180/110 mmHg) with acute damage to the target organs. Prompt treatment with intravenous antihypertensive therapy is generally required; over the first few minutes or within 2 hours, blood pressure should be reduced by 20 – 25%. Severe hypertension without acute target organ damage is defined as hypertensive urgency.; blood pressure should be reduced gradually over 24 – 48 hours with oral antihypertensive therapy. If blood pressure is reduced too quickly in the management of hypertensive crises, there is a risk of reduced organ perfusion leading to cerebral infarction, blindness, deterioration in renal function, and myocardial ischaemia.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 27 - What is nimodipine used predominantly in the treatment of? ...

    Incorrect

    • What is nimodipine used predominantly in the treatment of?

      Your Answer:

      Correct Answer: Prevention and treatment of vascular spasm following subarachnoid haemorrhage

      Explanation:

      Nimodipine is a smooth muscle relaxant that is related to nifedipine, but the effects preferentially act on cerebral arteries. It is exclusively used for the prevention and treatment of vascular spasm after an aneurysmal subarachnoid haemorrhage.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 28 - Nifedipine commonly causes which of the following adverse effects? ...

    Incorrect

    • Nifedipine commonly causes which of the following adverse effects?

      Your Answer:

      Correct Answer: Ankle oedema

      Explanation:

      Most common adverse effects of Nifedipine include:
      Peripheral oedema (10-30%)
      Dizziness (23-27%)
      Flushing (23-27%)
      Headache (10-23%)
      Heartburn (11%)
      Nausea (11%)

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 29 - The QRS duration of a broad-complex tachyarrhythmia is: ...

    Incorrect

    • The QRS duration of a broad-complex tachyarrhythmia is:

      Your Answer:

      Correct Answer: Greater than or equal to 0.12 s

      Explanation:

      It’s a broad-complex tachycardia if the QRS duration is 0.12 seconds or more. It’s a narrow-complex tachycardia if the QRS complex is shorter than 0.12 seconds. The QRS duration should be examined if the patient with tachyarrhythmia is stable.  

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

  • Question 30 - An 82 year old man taking warfarin as a maintenance medication comes in...

    Incorrect

    • 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:

      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.

    • This question is part of the following fields:

      • Cardiovascular
      • Pharmacology
      0
      Seconds

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