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Question 1
Incorrect
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Arterioles stemming from the coronary artery can also empty into the heart directly via the:
Your Answer: All arterioles empty into the coronary sinus or anterior cardiac vein
Correct Answer: Arteriosinusoidal vessels
Explanation:Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers. They include arteriosinusoidal vessels, which connect the arterioles to the heart chambers. The thebesian veins drain the capillaries into the chambers and the arterioluminal vessels drain small arteries directly into the chambers.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 2
Correct
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Which ion channel does not contribute to the myocardial action potential?
Your Answer: Chloride channel
Explanation:The upstroke in the cardiac action potential is due to opening of the sodium channels and an influx of sodium into the cell. The initial repolarization phase is due to transient opening of the potassium channels along with calcium channels. Influx of calcium causes the prolonged plateau phase of the action potential. Delayed opening of the rectifier potassium channel and delayed closure of the calcium channel leads to the repolarization phase of cardiac action potential.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 3
Incorrect
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Concerning coronary arteries, what is the net effect of B2 stimulation on the heart (e.g. Running athlete)?
Your Answer: Vasoconstriction via production of metabolites
Correct Answer: Vasodilation via production of metabolites
Explanation:The coronary arterioles contain α-adrenergic receptors, which cause vasoconstriction, and β-adrenergic receptors, which cause vasodilation. Activity in the noradrenergic nerves to the heart and injections of norepinephrine cause coronary vasodilation. However, norepinephrine also increases the heart rate and the force of cardiac contraction, and the vasodilation is due to production of vasodilator metabolites in the myocardium secondary to the increase in its activity. As exercise has the same effect as sympathetic stimulation, it will result in vasodilation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 4
Correct
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Myocardium requires more oxygen to expel blood in:
Your Answer: A stenotic aortic valve
Explanation:In aortic valve stenosis, increased ventricular pressure Is needed to expel the blood into the aorta. Increased pressure means increased contractility hence increase O2 consumption by the heart muscles.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 5
Correct
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Which of the following components regulate cardiac output?
Your Answer: All of the above
Explanation:Cardiac output is regulated by the autonomic nervous system with sympathetic nerves having a positive chronotropic and inotropic effect and parasympathetic nerves having the opposite effect. An increase in preload will increase cardiac output likewise an afterload increase will also increase cardiac output.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 6
Correct
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Calcium is mobilized from the sarcoplasmic reticulum through:
Your Answer: Ryanodine receptor (RyR2) calcium release channels
Explanation:During the plateau phase of the action potential, calcium from the extracellular fluid enters through the L type of calcium channels. This entry triggers the release of more calcium from the sarcoplasmic reticulum via the ryanodine receptors. As a result intracellular calcium increases binding to troponin C resulting in contraction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 7
Incorrect
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In the blood supply of the heart, ‘dominance’ refers to the coronary artery which supplies the?
Your Answer: Left ventricle
Correct Answer: Posterior interventricular artery
Explanation:Dominance of the coronary artery system is defined by the artery that gives rise to the posterior interventricular artery. Dominance of the right coronary artery is more common (68%). It gives rise to the large posterior interventricular branch which goes down to the apex of the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 8
Correct
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When looking at the JVP what does the c wave signify:
Your Answer: Isovolumetric ventricular contraction
Explanation:The C wave signifies a rise in the atrial pressure during isovolumetric contraction due to the tricuspid valve bulging into the atria.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 9
Incorrect
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The T-tubular system in cardiac muscle is:
Your Answer: Has dihydropyridine receptors which act as calcium activated Ca2+ release channels.
Correct Answer: Transmits action potential from sarcolemma to the SR to allow for Ca2+ release into the cytoplasm
Explanation:Action potentials are transmitted to the fibrils of a fiber through the T tubule system. It triggers the release of Ca 2+ from the terminal cisterns. Depolarization of the T tubules activates the sarcoplasmic reticulum through the dihydropyridine receptors, which are voltage gated calcium channels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 10
Correct
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What is the isolated effect of B2 stimulation on the coronaries?
Your Answer: Vasodilatation
Explanation:Norepinephrine and epinephrine are agonists for all adrenergic receptor subtypes, although with varying affinities. Based on their physiology and pharmacology, adrenergic receptors have been divided into two principal types: alpha and beta. These types have been further differentiated into alpha-1, alpha-2, b1, and b2 receptors.
Alpha-1 Receptors are located on postsynaptic cells in smooth muscle and elicit vasoconstriction.
Alpha-2 receptors are localized on presynaptic membranes of postganglionic nerve terminals that synthesize norepinephrine. When activated by catecholamines, alpha-2 receptors act as negative feedback controllers, inhibiting further norepinephrine release.
Activation of myocardial b1 receptors stimulates the rate and strength of cardiac contraction, and consequently increases cardiac output. b1 Receptor activation also stimulates renin release from the kidney. Another class of antihypertensive agents acts by inhibiting b1 receptors.
Activation of b2 receptors by epinephrine relaxes vascular smooth muscle and results in vasodilation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 11
Incorrect
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Which is the most common site for primary cardiac tumours to occur in adults?
Your Answer: Left atrial appendage
Correct Answer: Left atrium
Explanation:Myxomas are the most common type of primary heart tumour. The tumour is derived from multipotential mesenchymal cells and may cause a ball valve-type obstruction. About 75% of myxomas occur in the left atrium of the heart, usually beginning in the wall that divides the two upper chambers of the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 12
Correct
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The coronary sinus drains into the:
Your Answer: Right atrium
Explanation:The coronary sinus drains into the right atrium. Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 13
Incorrect
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Question 14
Incorrect
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Digoxin causes:
Your Answer: Na/k ATPase stimulation
Correct Answer: Increase in cytosolic calcium concentration
Explanation:Digoxin is a positive inotrope which inhibits NA/K ATPase, increases cardiac contractility and can cause hypokalaemia.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 15
Correct
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In which area is depolarization initiated?
Your Answer: SA node
Explanation:SA node is the pacemaker of the heart. It determines the rate of contractions. It is the place where depolarization is initiated. It exhibits phase 4 depolarization or automaticity. Electrical impulses then spread to the AV node, purkinje fibers, bundle of his and the ventricular muscles.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 16
Incorrect
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Where does the SA node develop?
Your Answer: From structures on the left side of the embryo
Correct Answer: From structures on the right side of the embryo.
Explanation:The SA node develops from the right side of the embryo and the AV node from the left. This is the reason why in adults the right vagus supplies the SA node and the left vagus supplies the AV node.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 17
Incorrect
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Which is the commonest cardiovascular abnormality seen in an adult patient with Marfan’s syndrome?
Your Answer: Aortic regurgitation
Correct Answer: Aortic aneurysm
Explanation:Marfan syndrome (MFS) is a genetic disorder of connective tissue. The degree to which people are affected varies. People with Marfan’s tend to be tall, and thin, with long arms, legs, fingers and toes. They also typically have flexible joints and scoliosis. The most serious complications involve the heart and aorta with an increased risk of mitral valve prolapse and aortic aneurysm.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 18
Incorrect
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Which of the following phases in depolarization and repolarization of cardiac muscle cells are caused by the inactivation of Na+ channels?
Your Answer: Phase 3 : resting membrane potential
Correct Answer: Phase 1 : rapid repolarization
Explanation:Phase 0 is caused by the sodium current. Voltage gated sodium channels open leading to the influx of sodium into the cardiac muscle cell. Phase 1 is the rapid transient repolarization phase which is caused by the inactivation of the voltage gated sodium channels and opening of the voltage gated potassium channels along with opening of the slow calcium channels. Phase 2 which is the plateau is caused by opening of the slow calcium channels. Phase 4 is caused by closing of the slow calcium channels and opening of the potassium channels leading to efflux of potassium leading to the establishment of the resting membrane potential.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 19
Correct
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The isoforms of nitric oxide synthase which are found in the nervous system (NOS1) and endothelial cells (NOS3) are activated by agents that increase which of the following intracellular electrolytes?
Your Answer: Ca
Explanation:Synthesis of nitric oxide is stimulated by activation of the NMDA receptors by certain agents. This leads to opening of the Calcium channels and an influx of calcium into the cell. This will activate the nitric oxide synthase. Nitric oxide is produced on demand.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 20
Incorrect
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Which one of the following have not been shown to improve mortality in patients with chronic heart failure?
Your Answer: Nitrates and hydralazine
Correct Answer: Furosemide
Explanation:A number of drugs have been shown to improve mortality in patients with chronic heart failure:
- ACE inhibitors (SAVE, SOLVD, CONSENSUS)
- spironolactone (RALES)
- beta-blockers (CIBIS)
- hydralazine with nitrates (VHEFT-1)
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 21
Correct
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Preload:
Your Answer: Is the degree to which the myocardium is stretched before is contracts
Explanation:Preload is end diastolic volume. It is the degree to which the heart muscle fiber is stretched when it fills up completely just before the heart contracts.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 22
Correct
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Stimulation of the carotid sinus results in:
Your Answer: Drop in blood pressure
Explanation:Stimulation of the carotid sinus will result in an increase in the baroreceptor discharge. This will travel via the afferent nerves to the medulla. Signals will pass through the vagus nerve to decrease the sympathetic outflow to the heart and the blood vessels. This inhibition will result in vasodilation of the blood vessels, venodilation and bradycardia hence decreasing the total peripheral resistance and lowering the blood pressure.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 23
Correct
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Question 24
Correct
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Question 25
Incorrect
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Which of the following supplies the AV node?
Your Answer: Left circumflex
Correct Answer: Right coronary artery
Explanation:The AV node is supplied by the right coronary artery near the origin of the posterior IV artery.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 26
Correct
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The basic unit of contraction in myocytes is:
Your Answer: Sarcomere
Explanation:Sarcomere is the organelle where calcium is stored to be released during contraction of the muscle. It is the basic unit of contraction in striated muscle fibers. As myocytes are also striated muscles, sarcomeres also forms the basic unit of contraction. The impulses travel along the membrane and via its interaction with the dihydropyridine receptors it releases the stored calcium.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 27
Incorrect
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Which of the following affects the magnitude of the action potential?
Your Answer: The amount of intracellular Ca2+
Correct Answer: Changes in the external Na+ concentration
Explanation:The magnitude of the action potential is determined by the sodium current. Increase in external sodium will result in increased influx of sodium and hence generation of a stronger action potential.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 28
Incorrect
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Which of the following does not contribute to increased stroke volume during exercise?
Your Answer: Increased sympathetic stimulation of ventricular muscle
Correct Answer: Increased length of filling time during diastole
Explanation:Prolonged aerobic exercise training may also increase stroke volume, which frequently results in a lower (resting) heart rate. Reduced heart rate prolongs ventricular diastole (filling), increasing end-diastolic volume, and ultimately allowing more blood to be ejected.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 29
Incorrect
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Which one of the following is a cause of a soft second heart sound?
Your Answer: Aortic regurgitation
Correct Answer: Aortic stenosis
Explanation:Second heart sound (S2) forms the dub of lub-dub and is composed of components A2 and P2. •   loud: hypertension•   soft: AS•   fixed split: physiological split (normally occurs during inhalation), right bundle branch block, pulmonary stenosis, and atrial septal defect.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 30
Correct
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With regards to the cardiac cycle which of the following is true
Your Answer: Right atrial systole occurs before left atrial systole: as below
Explanation:Cardiac cycle: The first event in the cycle is atrial depolarization (a P wave on the surface ECG) follows by RIGHT ATRIAL and then LEFT ATRIAL contraction. Ventricular activation (QRS) follows after a short interval (the PR interval). LEFT VENTRICULAR contraction starts shortly thereafter RIGHT VENTRICULAR contraction begins. At the end, the aortic valve closure is followed by pulmonary valve closure.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 31
Incorrect
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In the cardiac cycle, all of the following are true except:
Your Answer: The left ventricular pressure is maximal just before the aortic valve opens
Correct Answer: Mitral valve is closed by contraction of papillary muscles
Explanation:Mitral valve is closed by contraction of papillary muscles: This statement is incorrect. The mitral valve closes due to the pressure difference between the left ventricle and the left atrium at the onset of ventricular systole. The papillary muscles contract to prevent prolapse of the valve into the atrium but do not cause the valve to close.
The left ventricular volume is maximal at the end of atrial systole: This statement is true. At the end of atrial systole, the atria have pushed the remaining blood into the ventricles, making the ventricular volume maximal (end-diastolic volume).
The left ventricular pressure is maximal just before the aortic valve opens: This statement is true. Left ventricular pressure peaks just before the aortic valve opens, as the ventricle contracts to overcome the pressure in the aorta.
The ejection fraction is about 55%: This statement is true. The ejection fraction, which is the percentage of blood ejected from the ventricles with each contraction, is typically around 55%.
The ‘a’ wave is due to atrial systole: This statement is true. The ‘a’ wave on the venous pressure curve corresponds to atrial systole, reflecting the increased pressure from atrial contraction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 32
Incorrect
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Relaxation of the cardiac muscle at the actin-myosin cross bridges is initiated by binding of which molecule to the exposed site on the myosin.
Your Answer: Calcium
Correct Answer: ATP
Explanation:A crossbridge is a myosin projection, consisting of two myosin heads, that extends from the thick filaments. Each myosin head has two binding sites: one for ATP and another for actin. The binding of ATP to a myosin head detaches myosin from actin, thereby allowing myosin to bind to another actin molecule. Once attached, the ATP is hydrolysed by myosin, which uses the released energy to move into the cocked position whereby it binds weakly to a part of the actin binding site.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 33
Correct
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The Sinoatrial node in the majority of people is supplied by the?
Your Answer: Right coronary artery
Explanation:In 60% of people, the SA node is supplied by the right coronary artery branch and in 40% of the people by the left coronary artery.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 34
Incorrect
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Which of the following regulates the calcium release channels?
Your Answer: Phospholambin
Correct Answer: Calstabin 2
Explanation:Ca2+ is released from the SR through a Ca2+ release channel, a cardiac isoform of the ryanodine receptor (RyR2), which controls intracytoplasmic [Ca2+] and, as in vascular smooth-muscle cells, leads to the local changes in intracellular [Ca2+] called calcium sparks. A number of regulatory proteins, including calstabin 2, inhibit RyR2 and, thereby, the release of Ca2+ from the SR.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 35
Incorrect
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The ability of the SA node cells to allow ionic flow through channels activated in a hyperpolarized state is known as:
Your Answer: Depolarization
Correct Answer: Pace maker potential
Explanation:Rhythmically discharging cells have a membrane potential that, after each impulse, declines to the firing level. Thus this prepotential or Pacemaker potential triggers the next impulse. The inherent leakiness of the sinus nodal fibers to Na+ and Ca2+ causes their self excitation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 36
Incorrect
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The following contributes to the rate of depolarization?
Your Answer: Hypoxia
Correct Answer: All of the options given
Explanation:Depolarization occurs due to impulses generated by the SA node. As the heart beats to the rhythm of the SA node, certain factors will effect the rate of depolarization. All the mentioned options effect the rate of depolarization.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 37
Correct
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Question 38
Incorrect
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Concerning surface anatomy, where is the base of the heart
Your Answer: 5th intercostal space mid clavicular line
Correct Answer: 2nd left costal to 3rd right costal cartilage
Explanation:The base of the heart, also known as the superior border of the heart corresponds to a line connecting the inferior border of the 2nd left costal cartilage to the superior border of the 3rd right costal cartilage.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 39
Incorrect
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What is troponin?
Your Answer: A myosin heavy chain
Correct Answer: A component of thin filaments
Explanation:Skeletal muscle cytoplasmic proteins include myosin and actin (also known as thick and thin filaments, respectively) which are arranged in a repeating unit called a sarcomere. Troponin is a component of thin filaments (along with tropomyosin), and is the protein to which calcium binds.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 40
Incorrect
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Regarding the surface anatomy of the orifices of the heart, where is the aortic valve located?
Your Answer: Opposite the right 3rd intercostal space
Correct Answer: Opposite the left 3rd intercostal space to the left of the sternum
Explanation:The aortic valve is situated in the left 3rd intercostal space just beneath the sternum.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 41
Incorrect
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Which of the following best describes the cardiac muscle?
Your Answer: Smooth and involuntary
Correct Answer: Striated and involuntary
Explanation:Cardiac muscle (heart muscle) is an involuntary, striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 42
Incorrect
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The hyperpolarization phase of pacemaker cells is dominated by ____ current.
Your Answer: Ca++
Correct Answer: K+
Explanation:The hyperpolarization phase is a continuation of the repolarization phase but the membrane potential dips below the resting membrane potential. This results due to the fact that the K+ channels take a longer time to close than the Na+ channels. Hence efflux of the K+ will result in hyperpolarization.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 43
Correct
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When the heart rate is increased (to pathological levels) which of the following is correct when comparing the duration of diastole to systole?
Your Answer: It is shortened to a greater degree
Explanation:The duration of systole is more fixed than the duration of diastole. When the heart rate increases the timing of the systole remains more or less the same however diastole decreases.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 44
Incorrect
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Which of the following is the most common causative organism in infective endocarditis?
Your Answer: Staphylococcus aureus
Correct Answer: Streptococcus viridans
Explanation:Viridans Alpha-haemolytic streptococci, that are present in the mouth are the most frequently isolated microorganisms when the infection is acquired in a community setting. In contrast, Staphylococcus blood stream infections are frequently acquired in a health care setting where they can enter the blood stream through procedures that cause break in the integrity of skin like surgery, catheterisation or during access of long term indwelling catheters or secondary to intravenous injection of recreational drugs.Prosthetic valve endocarditis is commonly caused by Staphylococcus epidermidis as it is capable of growing as a biofilm on plastic surfaces
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 45
Incorrect
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When is the blood pressure at its lowest during pregnancy?
Your Answer: First trimester
Correct Answer: Second trimester
Explanation:It is lowest during the second trimester.
Previous studies have reported changes in blood pressure (BP) throughout pregnancy, and it was generally accepted that in clinically healthy pregnant women, BP falls gradually at first trimester, reaching the lowest around 22–24 weeks, rising again from 28 weeks, and reaching preconception levels by 36 weeks of gestation
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 46
Correct
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Question 47
Correct
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Water hammer pulse is found in:
Your Answer: Aortic insufficiency
Explanation:Watson’s water hammer pulse is the medical sign which describes a pulse that is bounding and forceful, rapidly increasing and subsequently collapsing, as if it were the sound of a water hammer that was causing the pulse. A water hammer was a Victorian toy in which a tube was half filled with fluid, the remainder being a vacuum. The child would invert and reinvert the tube; each time the impact of the fluid at each end would sound like a hammer blow. This is associated with increased stroke volume of the left ventricle and decrease in the peripheral resistance leading to the widened pulse pressure of aortic regurgitation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 48
Correct
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Which of the following does not lower ventricular rate in atrial fibrillation?
Your Answer: Adrenaline
Explanation:Adrenaline is a sympathetic neurotransmitter which increases the heart rate. During atrial fibrillation the atria is contracting at more than 200 beats/min. Acetylcholine is a parasympathetic neurotransmitter decreasing the heart rate. Digital also depresses the conduction at the AV conduction. Vagal discharge and occulocardiac reflux decrease the heart rate and convert the tachycardia into normal sinus rhythm.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 49
Correct
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Concerning surface anatomy, where is the aortic valve found?
Your Answer: Situated in the left third intercostal space underneath the sternum
Explanation:The aortic valve is situated in the left 3rd intercostal space just beneath the sternum.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 50
Correct
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The coronary arteries fill during?
Your Answer: Diastole
Explanation:During systole the coronary arteries collapse as a result of the pressure due to contraction that is exerted on them. During diastole the heart muscle relaxes and the pressure on the coronary vessels is relieved allowing blood to flow through them to the subendocardium.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 51
Incorrect
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Question 52
Incorrect
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AV valves open during?
Your Answer: Isovolumetric contraction of ventricles
Correct Answer: Early diastole
Explanation:The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat, and so includes the diastole, the systole, and the intervening pause.The first stage, diastole, is when the semilunar valves (the pulmonary valve and the aortic valve) close, the atrioventricular (AV) valves (the mitral valve and the tricuspid valve) open, and the whole heart is relaxed. The second stage, atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle.The third stage, isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. The fourth stage, ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. During the fifth stage, isovolumic relaxation time, pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 53
Correct
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What type of intercellular connection found between cardiac muscle fibers allow for the spread of excitation from one cell to another?
Your Answer: Gap junctions
Explanation:The cardiac muscles have gap junctions in-between the cells. They form low resistance passages, which allow ions to diffuse through every muscle fiber rapidly and result in the cardiac muscles functioning as a syncytium, without any protoplasmic bridges involved.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 54
Incorrect
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During which phase of the cardiac cycle does most of the ventricular filling occur?
Your Answer: Isovolumetric ventricular relaxation
Correct Answer: Ventricular diastole
Explanation:During the phase of ventricular diastole when the heart muscle relaxes and all the valves are open, blood flows easily into the heart. This is the phase of rapid ventricular filling. During isovolumetric contraction and relaxation the volume of blood in the heart does not change. During ventricular ejection blood enters into the aorta and pulmonary vessels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 55
Correct
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Which of the following are responsible for the 4th heart sound?
Your Answer: Ventricular hypertrophy
Explanation:The fourth heart sound is not normally audible in a normal adult. It occurs as a consequence of ventricular hypertrophy. It is caused by filling of the ventricle in atrial systole.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 56
Incorrect
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Which of the following corresponds to an oblique line drawn from the sternal end of the left 3rd costal cartilage to the sternal end of the right 6th costal cartilage?
Your Answer: Inter-ventricular septum
Correct Answer: Atrio-ventricular (coronary) groove
Explanation:The AV groove corresponds to the right border of the heart. The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 57
Incorrect
-
Nitric oxide triggers vascular smooth muscle contraction through activation of which enzyme?
Your Answer: Phospholipase c
Correct Answer: Guanylyl cyclase
Explanation:Impaired production or excess catabolism of NO impairs this endothelium-dependent vasodilator function and may contribute to excessive vasoconstriction under various pathological situations.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 58
Incorrect
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The internodal tract of Bachman:
Your Answer: Does not contain purkinje fibers
Correct Answer: Connects the SA node to the AV node
Explanation:Internodal tract of Bachman connects the SA node to the AV node conducting the electrical impulses generated from the SA node to the AV node and from the AV node to the rest of the electrical complex of the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 59
Incorrect
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Which of the following structures of the cardiac conduction system is located in the right posterior portion of the interatrial septum?
Your Answer: Bundle of his
Correct Answer: AV node
Explanation:AV node is located at the right posterior portion of the interatrial septum.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 60
Correct
-
Troponin I is inhibited by calcium binding to:
Your Answer: Troponin c
Explanation:At rest troponin I is bound to actin and tropomyosin and covers the site where the myosin head interacts with actin. When calcium enters into the muscle, it binds with troponin C and cause a structural change in troponin I which moves out of the myosin binding site and causes the cross bridges between the actin and myosin filaments to occur.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 61
Correct
-
The right border of the heart corresponds to which line on the surface of the chest?
Your Answer: Line drawn from the 3rd right costal cartilage to the 6th right costal cartilage
Explanation:The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 62
Incorrect
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How does pregnancy affect the cardiac output of a patient?
Your Answer: Increased cardiac output due to increase in stroke volume, whilst the heart rate remains unchanged
Correct Answer: Increased cardiac output due to increase in heart rate and stroke volume
Explanation:Cardiac Output increases to a similar degree as the blood volume. During the first trimester cardiac output is 30-40% higher than in the non-pregnant state. Steady rises are shown on Doppler echocardiography, from an average of 6.7 litres/minute at 8-11 weeks to about 8.7 litres/minute flow at 36-39 weeks; they are due, primarily, to an increase in stroke volume (35%) and, to a lesser extent, to a more rapid heart rate (15%). There is a steady reduction in systemic vascular resistance (SVR) which contributes towards the hyperdynamic circulation observed in pregnancy
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 63
Correct
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What is the most common cardiac defect seen in patients with Down’s syndrome?
Your Answer: Atrioventricular septal defect
Explanation:The rate of congenital heart disease in new-borns with Down syndrome is around 40%. Of those with heart disease, about 80% have an atrioventricular septal defect or ventricular septal defect with the former being more common. Mitral valve problems become common as people age, even in those without heart problems at birth.[3] Other problems that may occur include tetralogy of Fallot and patent ductus arteriosus.[38] People with Down syndrome have a lower risk of hardening of the arteries
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 64
Correct
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Which of the following suggests the presence of mitral regurgitation as well as mitral stenosis?
Your Answer: Displaced apex beat
Explanation:Mitral stenosis on its own does not lead to left ventricular dilatation and hence a displaced apex beat. Thus a displaced apex beat is suggestive of mixed mitral disease. The other options occur in mitral stenosis.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 65
Correct
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When observing a JVP, which of the following would lead to prominent v waves?
Your Answer: Tricuspid regurgitation
Explanation:The v wave corresponds to Venous filling when the tricuspid valve is closed and venous pressure increases from venous return. In Tricuspid regurgitation there is additional blood from the regurgitant flow and thus this leads to a more prominent V wave.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 66
Correct
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Question 67
Incorrect
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Impulse conduction through the AV node is slow and depends on the action potential produced by which of the following.
Your Answer: Sodium diffusion
Correct Answer: Calcium flux
Explanation:The action potentials in the SA and AV nodes are largely due to Ca2+, with no contribution by Na+ influx.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 68
Incorrect
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The most resistant area in the brain to hypoxia is:
Your Answer: Basal ganglia
Correct Answer: Brain stem
Explanation:The structures in the brainstem are more resistant to hypoxia than the cerebral cortex and the rest of the brain structures.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 69
Incorrect
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Activation of nitric oxide synthesis by endothelial cells is triggered by:
Your Answer: Bradykinin
Correct Answer: All of the above
Explanation:Acetylcholine, histamine, bradykinin, vasoactive intestinal peptide (VIP) and shear stress on the endothelial cells causing the release of NO. NO is formed from arginine and causes vasodilatation of the blood vessels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 70
Correct
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The effects of β1 stimulation include the following
Your Answer: Increased strength of contraction
Explanation:β1 stimulation include the phosphorylation of L type Ca++ channels and phospholamban and increased Ca++ influx from myocytes.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 71
Incorrect
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Which structure forms the major part of the sternocostal surface of the heart?
Your Answer: Right atrium
Correct Answer: Right ventricle
Explanation:The anterior (sternocostal) surface is formed mainly by the right ventricle.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 72
Incorrect
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Which one of the following ECG findings is least associated with digoxin use?
Your Answer: Down-sloping ST depression
Correct Answer: Prolonged QT interval
Explanation:Digoxin ECG features:•   ST depression (‘reverse tick’)•   flattened/inverted T waves• Prolonged PR interval•   short QT interval•   arrhythmias e.g. AV block, bradycardia, ventricular tachycardia or fibrillation (for example paroxysmal atrial tachycardia with A-V block – so-called PAT with block) is said to be pathognomonic (i.e. diagnostic) of digoxin toxicity.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 73
Incorrect
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Question 74
Incorrect
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Transport of Ca2+ into the reticulum to initiate cardiac muscle relaxation in via:
Your Answer: Closure of the ryanodine receptor
Correct Answer: Serca (sarcoplasmic or endoplasmic reticulum Ca2+ ATPase)
Explanation:Phosphorylation of phospholamban, which increases calcium ATPase activity and sequestration of calcium in the sarcoplasmic reticulum. An increased rate of relaxation is explained because cAMP also activates the protein phospholamban, situated on the membrane of the SR, that controls the rate of uptake of calcium into the SR. The latter effect explains enhanced relaxation (lusitropic effect).
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 75
Incorrect
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Coronary vasoconstriction can be caused by:
Your Answer: Hypoxia
Correct Answer: Beta blockage
Explanation:Coronary arteries contain alpha and beta receptors. The alpha receptor stimulates vasoconstriction and beta receptors stimulate vasodilation. When the chronotropic and inotropic effects of noradrenergic receptors are blocked by a B blocking drug, stimulation of the noradrenergic nerves will cause coronary vasoconstriction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 76
Incorrect
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Cholinergic nerves from the vagus innervate the SA and AV nodes via which receptor in the heart?
Your Answer: B1 receptor
Correct Answer: M2 receptor
Explanation:M2 receptor is found in the heart. M3 and M4 are associated with smooth muscle.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 77
Correct
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Myocyte action potentials – Choose the false statement:
Your Answer: Repolarisation is due to net k+ influx
Explanation:Final repolarization (phase 3) to the resting membrane potential (phase 4) is due to closure of the Ca2+ channels and a slow, delayed increase of K+ efflux through various types of K+ channels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 78
Incorrect
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Absolute refractory period in a cardiac action potential graph occurs during.
Your Answer: Plateau phase
Correct Answer: All of the above
Explanation:Absolute refractory period (ARP): the cell is completely unexcitable to a new stimulus and occurs from phase 0 – 2 i.e. depolarisation, early repolarisation and plateau phase.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 79
Incorrect
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Which of the following is true of the Natriuretic hormones?
Your Answer: They are potent vasoconstrictors
Correct Answer: They are released in response to hypervolemia
Explanation:Natriuretic hormones are vasodilators released in response to hypervolemia.
Natriuretic hormones (NH) include three groups of compounds: the natriuretic peptides NPs (ANP, BNP and CNP), the gastrointestinal peptides (guanylin and uroguanylin), and endogenous cardiac steroids. These substances induce the kidney to excrete sodium and therefore participate in the regulation of sodium and water homeostasis, blood volume, and blood pressure (BP). In addition to their peripheral functions, these hormones act as neurotransmitters or neuromodulators in the brain.
Atrial natriuretic peptide (ANP) plays a crucial role in blood pressure regulation by inducing natriuresis and diuresis in the kidney, inhibiting renin secretion, aldosterone production, and promoting vasorelaxation. Â Two paracrine factors derived from endothelial cells play important roles in modulating ANP secretion. Endothelin, a potent vasoconstrictor, stimulates ANP secretion and augments stretch induced ANP secretion. The dramatic increase in ANP release produced by cardiac ischemia appears to be mediated in part by endothelin. Nitric oxide (NO), an important vasodilator, is also produced by endothelial cells and inhibits ANP secretion.
Brain natriuretic peptide (BNP) shares ANP’s receptor but is primarily associated with antifibrotic effects in ventricular remodeling, serving as a biomarker for heart failure and myocardial infarction.
C-type natriuretic peptide (CNP) acts locally in an autocrine/paracrine manner, exerting potent cardiovascular effects, including vasorelaxation and vascular remodeling post-injury. NPs also demonstrate diverse effects beyond cardiovascular and renal systems, such as bronchodilation, anti-inflammatory actions, and metabolic effects on adipose tissue and long bones.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 80
Incorrect
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Afferent fibers from the baroreceptors of the great arteries form branches of which cranial nerves?
Your Answer: Vagus and hypoglossal nerve
Correct Answer: Glossopharyngeal and vagus nerves
Explanation:The receptors of the carotid sinus are innervated by the carotid sinus nerve, a branch of the glossopharyngeal nerve. The aortic arch receptors located in the arch of the aorta are innervated by the aortic depressor nerve, a branch of the vagus nerve.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 81
Correct
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Which vaso metabolite decreases coronary blood flow?
Your Answer: Endothelin
Explanation:Decreased O2, increased CO2, lactate, prostaglandins, adenine nucleotides, adenosine, H+, K+ and cyanide produce vasodilation and thus an increase in coronary blood flow.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 82
Incorrect
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Catecholamines…
Your Answer: None of the above
Correct Answer: Activate adenylyl cyclase
Explanation:Norepinephrine and epinephrine activate or deactivate adenylyl cyclase resulting in a decrease or an increase in the production of cAMP.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 83
Correct
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Question 84
Incorrect
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Why does arterial blood pressure drop during pregnancy?
Your Answer: The enlarged uterus leads to inferior vena cava compression
Correct Answer: Progesterone relaxes vascular smooth muscle
Explanation:Progesterone relaxes vascular smooth muscle thus resulting In a decrease in total peripheral resistance. This accounts for the increase in the cardiac output.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 85
Correct
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The triangle with the heart at its centre, using limb leads is called:
Your Answer: Einthoven
Explanation:The Einthoven triangle is formed by placing the limb leads on both the arms and on the left leg with the heart in the centre.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 86
Correct
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The function of ATP in cardiac muscle contraction includes:
Your Answer: Binding to myosin after the power stroke to allow uncoupling of actin and myosin
Explanation:After calcium binds to the troponin C, there is a conformational change in the structure of troponin I and tropomyosin, which moves out of the way and frees the site where myosin can bind to actin. This results in the formation of the cross linkage of the actin and myosin giving rise to the power stroke in the contraction phase. This occurs with the release of ADP. When ATP combines to this complex it breaks and the cycle repeats itself.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 87
Correct
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Which factor produced by the endothelium is responsible for the regulation of vascular cell growth?
Your Answer: Vascular endothelial growth factor (VEGF)
Explanation:VEGF is produced by the endothelial cells and is the major growth factor responsible for causing vasculogenesis. Some isoforms of this growth factor also have a prominent role in formation of lymphatic vessels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 88
Correct
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Regarding cardiac muscle contractility, the afterload refers to:
Your Answer: The resistance against which blood is expected
Explanation:The afterload for the left ventricle is the aortic pressure. Hence it is this pressure that offers resistance against which the blood is to be expelled from the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 89
Incorrect
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If both the noradrenergic and the cholinergic systems are blocked in the heart, the rate will be approximately:
Your Answer: 50/ min
Correct Answer: 100/min
Explanation:The normal heart beat is about 70/min. This is due to a predominant parasympathetic activity. If sympathetic activity was unopposed the heart rate would have been 150/min. When both the noradrenergic and cholinergic systems are blocked the heart rate is 100/min. This is the normal firing rate of the SA node.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 90
Incorrect
SESSION STATS - PERFORMANCE PER SPECIALTY
