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  • Question 1 - Depolarization spreads rapidly through cardiac muscle fibers because of the presence of: ...

    Correct

    • Depolarization spreads rapidly through cardiac muscle fibers because of the presence of:

      Your Answer: Gap junctions

      Explanation:

      The cardiac muscles have gap junctions in between the cells. They allow for the formation of 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      19.4
      Seconds

  • Question 2 - The following is true of the sinus node: ...

    Correct

    • The following is true of the sinus node:

      Your Answer: It generates impulses automatically & at a quicker rate than other cardiac cells

      Explanation:

      The SA node exhibits automaticity. It generates the impulses to which the heart beats. It fires at a faster speed than the rest of the nervous components of the heart i.e. the AV nodes, purkinje fibers. This is the reason when the SA node fails the heart beats to the rhythm of the AV node.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      90.6
      Seconds

  • Question 3 - Where does the SA node develop? ...

    Correct

    • Where does the SA node develop?

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      70.2
      Seconds

  • Question 4 - Myocardial fibers have a resting membrane potential of approximately: ...

    Correct

    • Myocardial fibers have a resting membrane potential of approximately:

      Your Answer: -90mv

      Explanation:

      The resting membrane potential of the mammalian heart is about -90 mv.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      256.1
      Seconds

  • Question 5 - The V wave in the jugular pulse is caused by: ...

    Correct

    • The V wave in the jugular pulse is caused by:

      Your Answer: Atrial filling

      Explanation:

      The v wave reflects the passive increase in pressure and volume of the right atrium as it fills in late systole and early diastole.

      The jugular vein pulsations usually have two elevations and two troughs. The first elevation (a wave) corresponds to the slight rise in atrial pressure resulting from atrial contraction. The first descent (x descent) reflects a fall in atrial pressure that starts with atrial relaxation. The second elevation (v wave) corresponds to ventricular systole when blood is entering the right atrium from the vena cavae while the tricuspid valve is closed. Finally, the second descent (y descent) reflects falling right atrial pressure as the tricuspid valve opens and blood drains from the atrium into the ventricle.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      99.3
      Seconds

  • Question 6 - In which organ will you find extremely porous sinusoidal capillaries, with discontinuous endothelium?...

    Incorrect

    • In which organ will you find extremely porous sinusoidal capillaries, with discontinuous endothelium?

      Your Answer: Kidneys

      Correct Answer: Liver

      Explanation:

      The liver is the organ which contains sinusoidal capillaries with discontinuous endothelium. The brain, lungs and the intestine all contain continuous capillaries, however the kidney contains fenestrated capillaries to aid in filtration.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      27.8
      Seconds

  • Question 7 - The following products of the vascular endothelium produce vasodilation except: ...

    Correct

    • The following products of the vascular endothelium produce vasodilation except:

      Your Answer: Endothelin

      Explanation:

      Endothelin: This is incorrect in the context of vasodilation. Endothelin is actually a potent vasoconstrictor produced by the endothelium, leading to the narrowing of blood vessels and increased blood pressure.

      Nitrous oxide (Nitric oxide): This is correct for vasodilation. Nitric oxide is a powerful vasodilator produced by the endothelium, which helps relax and widen blood vessels.

      Prostacyclin: This is correct for vasodilation. Prostacyclin (PGI2) is a vasodilator and inhibits platelet aggregation, helping to maintain blood flow and reduce clot formation.

      Endothelial-derived hyperpolarizing factor (EDHF): This is correct for vasodilation. EDHF causes vasodilation by hyperpolarizing the smooth muscle cells of blood vessels.

      Vascular endothelial growth factor (VEGF): This is correct for vasodilation. VEGF primarily promotes the growth of new blood vessels but also has vasodilatory effects through nitric oxide production.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      203.5
      Seconds

  • Question 8 - Which of the following regulates the calcium release channels? ...

    Incorrect

    • Which of the following regulates the calcium release channels?

      Your Answer: Both a and d

      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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      39.3
      Seconds

  • Question 9 - The internodal tract of Bachman: ...

    Incorrect

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      120.7
      Seconds

  • Question 10 - Afferent fibers from the baroreceptors of the great arteries form branches of which...

    Correct

    • Afferent fibers from the baroreceptors of the great arteries form branches of which cranial nerves?

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      22.7
      Seconds

  • Question 11 - The positive inotropic effect of digoxin is due to? ...

    Correct

    • The positive inotropic effect of digoxin is due to?

      Your Answer: Inhibition of the sodium potassium ATPase in the myocardium

      Explanation:

      Digitalis compounds are potent inhibitors of cellular Na+/K+-ATPase. This ion transport system moves sodium ions out of the cell and brings potassium ions into the cell. By inhibiting the Na+/K+-ATPase, cardiac glycosides cause the intracellular sodium concentration to increase. This then leads to an accumulation of intracellular calcium via the Na+/Ca++ exchange system. In the heart, increased intracellular calcium causes more calcium to be released by the sarcoplasmic reticulum, thereby making more calcium available to bind to troponin-C, which increases contractility (inotropy).

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      63.7
      Seconds

  • Question 12 - The principle by which the energy of contraction is proportional to the initial...

    Correct

    • The principle by which the energy of contraction is proportional to the initial length of cardiac muscle fiber is known as:

      Your Answer: Starling’s law

      Explanation:

      The Frank starling relationship describes that an increase in the venous return or the end diastolic volume will cause an increase in the stroke volume/ preload and also cardiac output. It stems from the fact that increase venous return will increase the stretch on the ventricular muscle fibers. The sarcomere will stretch a considerable length that is needed for maximum contraction and increased development of tension in the muscle fiber. The greater the venous return the greater the cardiac output. This relation is directly proportional.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      17.9
      Seconds

  • Question 13 - Which of the following is NOT an effect of a positive inotropic agent...

    Incorrect

    • Which of the following is NOT an effect of a positive inotropic agent on the heart?

      Your Answer: It increases the initial velocity of muscle shortening at all loads

      Correct Answer: It decreases the rate of rise in ventricular blood pressure during systole

      Explanation:

      Inotropic agents increase the contractility of the heart as well as the rate of rise in ventricular blood pressure during systole, generating a greater pressure and increasing the stroke volume e.g. like catecholamines do.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      79.5
      Seconds

  • Question 14 - Which of the atrial pressure changes represents the a-wave of the JVP ...

    Correct

    • Which of the atrial pressure changes represents the a-wave of the JVP

      Your Answer: Atrial systole

      Explanation:

      The a-wave created on the venous pulse curve occurs as a result of atrial systole. Due to the pressure build-up in the atria, it causes a back pressure in the vena cava. This pressure is exerted on the valve and this back pressure is what causes a slight increase in the venous pressure.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      11.6
      Seconds

  • Question 15 - Which of the following best describes the cardiac muscle? ...

    Correct

    • Which of the following best describes the cardiac muscle?

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      11.1
      Seconds

  • Question 16 - Which ion channel does not contribute to the myocardial action potential? ...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      43.1
      Seconds

  • Question 17 - The SA and AV nodes are usually supplied by which artery? ...

    Correct

    • The SA and AV nodes are usually supplied by which artery?

      Your Answer: Right coronary artery

      Explanation:

      The right coronary artery supplies the right atrium, right ventricle, SA and AV nodes.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.2
      Seconds

  • Question 18 - B1 adrenergic stimulation produces: ...

    Correct

    • B1 adrenergic stimulation produces:

      Your Answer: Increase in calcium cytosolic concentration

      Explanation:

      Norepinephrine secreted by the sympathetic endings binds to B1 receptors, and the resulting increase in intracellular cAMP facilitates the opening of L channels, increasing Ica and the rapidity of the depolarization phase of the impulse and activates PKA which leads to phosphorylation of the voltage-gated Ca2+ channels, causing them to spend more time in the open state.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      55.9
      Seconds

  • Question 19 - The following determines the strength of contraction ...

    Incorrect

    • The following determines the strength of contraction

      Your Answer: None of the above

      Correct Answer: Plateau phase

      Explanation:

      The plateau phase which follows is unique to myocytes and results from a small, but sustained inward calcium current through L-type calcium channels lasting 200-400 ms. This calcium influx is caused by a combined increase in permeability of the cell and especially the sarcolemmal membranes to calcium. This plateau (or refractory) phase in myocyte action potential prevents early reactivation of the myocytes and directly determines the strength of contraction

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      25.7
      Seconds

  • Question 20 - Which of the following intercellular connections is important in endothelial barrier function? ...

    Correct

    • Which of the following intercellular connections is important in endothelial barrier function?

      Your Answer: Tight junctions

      Explanation:

      Tight junctions surround the apical margins of the epithelial cells such as in the intestinal mucosa and the choroid plexus. They are also important to the endothelial barrier function. They are made up of ridges that adhere to each other strongly at the cell junction, obliterating the space completely between the cells.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      27.7
      Seconds

  • Question 21 - With regards to the cardiac cycle which of the following is true ...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      201.9
      Seconds

  • Question 22 - Where are the baroreceptors of the great arteries located? ...

    Incorrect

    • Where are the baroreceptors of the great arteries located?

      Your Answer: In the endothelium

      Correct Answer: In the adventitia

      Explanation:

      Arterial baroreceptors are located in the aortic arch and carotid sinuses, and are formed by small nerve endings present in the adventitia of these vessels.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      93.8
      Seconds

  • Question 23 - What is the effect of catecholamines (i.e. increased heart rate) on the pressure...

    Correct

    • What is the effect of catecholamines (i.e. increased heart rate) on the pressure volume loop?

      Your Answer: Shifts the diastolic pressure curve upward and leftward

      Explanation:

      Catecholamines have a positive ionotropic and chronotropic effect on the heart. The ventricles develop greater tension during systole resulting in an increase in the stroke volume. The increase in stroke volume results in a decrease in the end diastolic volume. This pushes the loop towards the left and upwards.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      370.7
      Seconds

  • Question 24 - The coronary arteries supply which part of the heart’s subendocardial region exclusively in...

    Incorrect

    • The coronary arteries supply which part of the heart’s subendocardial region exclusively in diastole?

      Your Answer: All chambers of the heart ( all of the above if you want )

      Correct Answer: Left ventricle

      Explanation:

      It is only during diastole that the blood flows to the subendocardial portion of the left ventricle, as the heart muscle relaxes and the coronary arteries regain their patency.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      48.5
      Seconds

  • Question 25 - The function of ATP in cardiac muscle contraction includes: ...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      62.7
      Seconds

  • Question 26 - Regarding cardiac muscle contractility, the afterload refers to: ...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      23
      Seconds

  • Question 27 - Vasodilatation of coronary arteries is caused by: ...

    Correct

    • Vasodilatation of coronary arteries is caused by:

      Your Answer: Hypoxia

      Explanation:

      The heart is highly metabolically active and boasts the highest oxygen consumption by mass of any organ. This demand for oxygen is met by the coronary circulation, which is responsible for delivering blood to the myocardium and represents approximately 5% of cardiac output. Vasodilation may be due to the local effect of hypoxia on coronary vessels, or local metabolic vasodilation, or the activation of β-adrenoceptors or some combination of these mechanisms.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      68.2
      Seconds

  • Question 28 - What is the most common cardiac defect seen in patients with Down’s syndrome?...

    Incorrect

    • What is the most common cardiac defect seen in patients with Down’s syndrome?

      Your Answer: Ventricular septal defect

      Correct 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

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      9.6
      Seconds

  • Question 29 - The following contributes to the rate of depolarization? ...

    Correct

    • The following contributes to the rate of depolarization?

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      20.3
      Seconds

  • Question 30 - In cardiac muscle, which of the following is directly responsible for the release...

    Correct

    • In cardiac muscle, which of the following is directly responsible for the release of Ca2+ stored in the sarcoplasmic reticulum (calcium-induced calcium release)?

      Your Answer: Ryanodine receptor (RyR)

      Explanation:

      Ryanodine receptor (RyR) is a ligand-gated Ca2+ channel with Ca2+ as its natural ligand. In skeletal muscle, Ca2+ entry from ECF by this route is not required for Ca2+ release. Instead, the DHPR that serves as the voltage sensor unlocks release of Ca2+ from the nearby SR via physical interaction with the RyR. The release is amplified through ca-induced ca release. However, in cardiac muscle, it is the influx of extracellular Ca2+ through the voltage-sensitive DHPR in the T system that triggers ca-induced ca release trough the RyR at the SR.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      28.4
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular (22/30) 73%
Medicine (22/30) 73%
Passmed
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