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  • Question 1 - Regarding the myofilament molecules, which of the following contains binding sites for calcium...

    Correct

    • Regarding the myofilament molecules, which of the following contains binding sites for calcium that helps to initiate contraction?

      Your Answer: Troponin c

      Explanation:

      Troponin T binds the troponin components to tropomyosin. Troponin I inhibits the interaction of myosin with actin and troponin C contains the binding sites for the Ca2+ that helps initiate contraction.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      25
      Seconds

  • Question 2 - The rate of depolarization of the SA node membrane potential is modulated by...

    Correct

    • The rate of depolarization of the SA node membrane potential is modulated by the following:

      Your Answer: All of the above

      Explanation:

      Rate of depolarization of the SA node is modulated by all of these.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.9
      Seconds

  • Question 3 - How does pregnancy affect the cardiac output of a patient? ...

    Incorrect

    • How does pregnancy affect the cardiac output of a patient?

      Your Answer: Increased cardiac output due to increase in heart rate only, the stroke volume 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

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      73.1
      Seconds

  • Question 4 - Depolarization of the T tubule membrane activates the sarcoplasmic reticulum via which receptors?...

    Correct

    • Depolarization of the T tubule membrane activates the sarcoplasmic reticulum via which receptors?

      Your Answer: Dihydropyridine receptors

      Explanation:

      Action potentials are transmitted to the fibrils of a fiber through the T tubule system. It triggers the release of Ca 2+ form the terminal cisterns. Depolarization of the T tubules activates the sarcoplasmic reticulum through the dihydropyridine receptors.

      Dihydropyridine receptors (DHPRs), are voltage-gated Ca2+ channels, and ryanodine receptors (RyRs), which are intracellular Ca2+ release channels, are expressed in diverse cell types, including skeletal and cardiac muscle.

      Ryanodine receptors (RyRs) are located in the sarcoplasmic/endoplasmic reticulum membrane and are responsible for the release of Ca2+ from intracellular stores during excitation-contraction coupling in both cardiac and skeletal muscle.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      55.2
      Seconds

  • Question 5 - Calcium induced calcium release occurs in the sarcoplasmic reticulum by activation of which...

    Correct

    • Calcium induced calcium release occurs in the sarcoplasmic reticulum by activation of which receptors

      Your Answer: Ryanodine receptors

      Explanation:

      Calcium-induced calcium release (CICR) describes a biological process whereby calcium is able to activate calcium release from intracellular Ca2+ stores (e.g., endoplasmic reticulum or sarcoplasmic reticulum). CICR occurs when the resulting Ca2+ influx activates ryanodine receptors on the SR membrane, which causes more Ca2+ to be released into the cytosol.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      10.2
      Seconds

  • Question 6 - Which vagus nerve mainly supplies the AV node? ...

    Incorrect

    • Which vagus nerve mainly supplies the AV node?

      Your Answer: Both left and right vagus

      Correct Answer: Left vagus

      Explanation:

      As the AV node develops from the left side of the embryo It is supplied by the left vagus nerve.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      19.1
      Seconds

  • Question 7 - All valves are closed in which phase of the cardiac cycle? ...

    Correct

    • All valves are closed in which phase of the cardiac cycle?

      Your Answer: Isovolumetric relaxation

      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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      17.2
      Seconds

  • Question 8 - Which of the following concerning PR interval is INCORRECT? ...

    Correct

    • Which of the following concerning PR interval is INCORRECT?

      Your Answer: Always measured from the beginning of p wave to the beginning of r wave

      Explanation:

      The PR interval measures the time from the start of atrial depolarization to the start of ventricular depolarization. The PR interval is only measured from the beginning of P wave to beginning of R wave if the Q wave is absent.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      20.3
      Seconds

  • Question 9 - Coronary flow is reduced during ...

    Incorrect

    • Coronary flow is reduced during

      Your Answer: Diastole

      Correct Answer: Tachycardia

      Explanation:

      Maximum amount of blood flow in the coronary arteries occur during diastole. When the heart rate increases which is also called tachycardia the duration of diastole decreases. Hence the amount of blood flow to the cardiac muscle also decreases.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      24.8
      Seconds

  • Question 10 - The posterior aspect of the interventricular septum is supplied by: ...

    Correct

    • The posterior aspect of the interventricular septum is supplied by:

      Your Answer: A branch of the right coronary artery

      Explanation:

      The posterior aspect of the heart is supplied by the posterior interventricular artery which is a branch of the right coronary artery.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      14.2
      Seconds

  • Question 11 - With regard to the endothelial structure, the epithelium constitute: ...

    Correct

    • With regard to the endothelial structure, the epithelium constitute:

      Your Answer: Simple squamous

      Explanation:

      The single layer of squamous epithelium lining the heart and blood vessels is known as the endothelium.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      10
      Seconds

  • Question 12 - The rate of depolarisation of the sinus node membrane potential is modulated by...

    Correct

    • The rate of depolarisation of the sinus node membrane potential is modulated by all the following except:

      Your Answer: Cardiac output

      Explanation:

      Cardiac output has no effect on the depolarization of the pacemaker potential of the heart.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      9.8
      Seconds

  • Question 13 - The triangle with the heart at its centre, using limb leads is called:...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      11.6
      Seconds

  • Question 14 - Blood flow to the subendocardial portions of the left ventricular muscle occurs mainly...

    Incorrect

    • Blood flow to the subendocardial portions of the left ventricular muscle occurs mainly during:

      Your Answer: Isovolumetric ventricular contraction

      Correct Answer: Diastole

      Explanation:

      The sub endocardium receives the least amount of blood from the coronary arteries. During systole the coronary arteries collapse as a result of the pressure from 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 sub endocardium.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      22.5
      Seconds

  • Question 15 - 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
      4.7
      Seconds

  • Question 16 - 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
      39.6
      Seconds

  • Question 17 - Digoxin causes: ...

    Incorrect

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.7
      Seconds

  • Question 18 - Myocardium requires more oxygen to expel blood in: ...

    Incorrect

    • Myocardium requires more oxygen to expel blood in:

      Your Answer: None of the above

      Correct 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      19.7
      Seconds

  • Question 19 - Isovolumetric ventricular contraction lasts for? ...

    Correct

    • Isovolumetric ventricular contraction lasts for?

      Your Answer: 0,05 s

      Explanation:

      Isovolumetric contraction lasts for about 0.05 seconds.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.8
      Seconds

  • Question 20 - What is the function of the BK channel on the vascular smooth muscle...

    Incorrect

    • What is the function of the BK channel on the vascular smooth muscle membrane?

      Your Answer: Promotes smooth muscle contraction opening the voltage gated Ca2+ channel

      Correct Answer: Massive K+ influx, increasing membrane potential, and shutting off the voltage gated Ca2+ channel

      Explanation:

      In vascular smooth muscles, Ca2+ influx via the voltage gated calcium channels increases the cytosolic calcium, as well as causing the release of calcium from the sarcoplasmic reticulum. The high calcium concentration increases the activity of the calcium activated potassium channels. These are known as BK channels. Massive influx of potassium shuts off the voltage gated calcium channels and causes relaxation of the vascular smooth muscle.

      The large-conductance voltage and calcium-sensitive BK channel is important in many electrically active cells. Its unique sensitivity to both intracellular calcium levels and membrane potential makes it a key regulator of intracellular calcium, a critical second messenger in cells.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      45.2
      Seconds

  • Question 21 - The coronary arteries fill during? ...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.5
      Seconds

  • Question 22 - Dicrotic notch is produced by which valves? ...

    Incorrect

    • Dicrotic notch is produced by which valves?

      Your Answer: Pulmonary and aortic

      Correct Answer: Aortic

      Explanation:

      The graph of aortic pressure throughout the cardiac cycle displays a small dip (the incisure or dicrotic notch) which coincides with the aortic valve closure. The dip in the graph is immediately followed by a brief rise (the dicrotic wave) then gradual decline.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      8.6
      Seconds

  • Question 23 - Endothelial cells produce the following substance(s): ...

    Correct

    • Endothelial cells produce the following substance(s):

      Your Answer: All of the above

      Explanation:

      Endothelial cells produce thromboxane, prostacyclins, nitric oxides, endothelins, IL-1 and TNF.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      5.9
      Seconds

  • Question 24 - 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
      7.3
      Seconds

  • Question 25 - The T-tubular system in cardiac muscle is: ...

    Incorrect

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      20.3
      Seconds

  • Question 26 - Which part of the ECG represents ventricular repolarisation? ...

    Incorrect

    • Which part of the ECG represents ventricular repolarisation?

      Your Answer: QT interval

      Correct Answer: T wave

      Explanation:

      Ventricular repolarisation is denoted by the T wave.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.6
      Seconds

  • Question 27 - Coronary arteries fill up during ...

    Correct

    • Coronary arteries fill up during

      Your Answer: Diastole

      Explanation:

      During contraction of the ventricular myocardium (systole), the subendocardial coronary vessels (the vessels that enter the myocardium) are compressed due to the high ventricular pressures. This compression results in momentary retrograde blood flow (i.e., blood flows backward toward the aorta) which further inhibits perfusion of myocardium during systole. However, the epicardial coronary vessels (the vessels that run along the outer surface of the heart) remain open. Because of this, blood flow in the sub endocardium stops during ventricular contraction. As a result, most myocardial perfusion occurs during heart relaxation (diastole) when the subendocardial coronary vessels are open and under lower pressure.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      5
      Seconds

  • Question 28 - Which structure forms the major part of the sternocostal surface of the heart?...

    Correct

    • Which structure forms the major part of the sternocostal surface of the heart?

      Your Answer: Right ventricle

      Explanation:

      The anterior (sternocostal) surface is formed mainly by the right ventricle.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      19.6
      Seconds

  • Question 29 - Where are the baroreceptors of the great arteries located? ...

    Incorrect

    • Where are the baroreceptors of the great arteries located?

      Your Answer: In the smooth muscle

      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
      15.5
      Seconds

  • Question 30 - The most resistant area in the brain to hypoxia is: ...

    Correct

    • The most resistant area in the brain to hypoxia is:

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      13.7
      Seconds

  • Question 31 - The ability of the SA node cells to allow ionic flow through channels...

    Correct

    • The ability of the SA node cells to allow ionic flow through channels activated in a hyperpolarized state is known as:

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      20.8
      Seconds

  • Question 32 - Which of the following suggests the presence of mitral regurgitation as well as...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      24.6
      Seconds

  • Question 33 - Xanthines such as caffeine and theophylline are positively inotropic due to: ...

    Correct

    • Xanthines such as caffeine and theophylline are positively inotropic due to:

      Your Answer: Inhibition of cAMP breakdown

      Explanation:

      Xanthines exert their positive inotropic effect by inhibiting the breakdown of the cAMP resulting in stronger and sustained contractions.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.4
      Seconds

  • Question 34 - A 55 year old cardiac patient is comfortable at rest but heavy housework...

    Correct

    • A 55 year old cardiac patient is comfortable at rest but heavy housework results in fatigue, palpitations or dyspnoea. What New York Heart Association class best describes the severity of their disease?

      Your Answer: NYHA Class II

      Explanation:

      New York Heart Association functional classification:

      Class I: no limitation is experienced in any activities; there are no symptoms from ordinary activities.

      Class II: slight, mild limitation of activity; the patient is comfortable at rest or with mild exertion.

      Class III: marked limitation of any activity; the patient is comfortable only at rest.

      Class IV: any physical activity brings on discomfort and symptoms occur at rest.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      14.9
      Seconds

  • Question 35 - In the jugular venous pressure wave… ...

    Incorrect

    • In the jugular venous pressure wave…

      Your Answer: ‘v’ wave coincide with rapid ventricular filling phase

      Correct Answer: Consists of 3 peaks and 2 troughs

      Explanation:

      The jugular venous pressure (JVP, sometimes referred to as jugular venous pulse) is the indirectly observed pressure over the venous system via visualization of the internal jugular vein. It can be useful in the differentiation of different forms of heart and lung disease. Classically three upward deflections (peaks) and two downward deflections (troughs) have been described:The upward deflections are the a (atrial contraction), c (ventricular contraction and resulting bulging of tricuspid into the right atrium during isovolumetric systole) and v = venous filling.The downward deflections of the wave are the x (the atrium relaxes and the tricuspid valve moves downward) and the y descent (filling of ventricle after tricuspid opening).

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      26.6
      Seconds

  • Question 36 - 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
      4.2
      Seconds

  • Question 37 - The a-wave is created by: ...

    Correct

    • The a-wave is created by:

      Your Answer: Regurgitation of some blood to the great veins when the atria contracts in 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
      21.5
      Seconds

  • Question 38 - Vasodilatation in skeletal muscle can be caused by: ...

    Incorrect

    • Vasodilatation in skeletal muscle can be caused by:

      Your Answer: Endothelin-1

      Correct Answer: Sympathetic cholinergic nerves

      Explanation:

      In skeletal muscles some fibers that cause vasodilation run with the nerves of the sympathetic system but are cholinergic in nature. These nerves are not active during rest but become active during exercise and stress.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      6.7
      Seconds

  • Question 39 - Which of the following pairs are correct concerning arteriolar tone? ...

    Incorrect

    • Which of the following pairs are correct concerning arteriolar tone?

      Your Answer: Neural control: vasoconstriction activated by sympathetic nerves

      Correct Answer: Hormonal control: catecholamines affect the adrenergic receptors of the vascular smooth muscle

      Explanation:

      Catecholamines released from the adrenal medulla act on the noradrenergic receptors of the vascular smooth muscles. In the skeletal muscles and liver it causes vasodilation whilst it causes vasoconstriction in the rest of the blood vessels of the body.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      41
      Seconds

  • Question 40 - Which of the following results in the resting membrane potential of a myocyte?...

    Incorrect

    • Which of the following results in the resting membrane potential of a myocyte?

      Your Answer: Activation of gated Na channels

      Correct Answer: Activation of outward K+ channels

      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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      43.8
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular (25/40) 63%
Medicine (25/40) 63%
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