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  • Question 1 - The amount of a substance taken up by an organ (or whole body)...

    Correct

    • The amount of a substance taken up by an organ (or whole body) per unit time is = (the arterial level - the venous level) * the blood flow. This statement describes?

      Your Answer: The Fick principle

      Explanation:

      The essence of the Fick principle is that blood flow to an organ can be calculated using a marker substance if the following information is known:- Amount of marker substance taken up by the organ per unit time- Concentration of marker substance in arterial blood supplying the organ- Concentration of marker substance in venous blood leaving the organ

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      6.8
      Seconds

  • Question 2 - Myocardial contractility is improved by: ...

    Correct

    • Myocardial contractility is improved by:

      Your Answer: Caffeine

      Explanation:

      Caffeine and other theophyllines breakdown cAMP and have a positive ionotropic effect on the heart. Drugs like quinidine, procainamide and conditions like hypoxia and hypercapnia decreases the contractility of the heart.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      3
      Seconds

  • Question 3 - Which of the following is a method for measurement of cardiac output? ...

    Correct

    • Which of the following is a method for measurement of cardiac output?

      Your Answer: Indicator dilution method

      Explanation:

      There are two methods of calculating the cardiac output in humans other than doppler with echocardiography: The direct Fick’s method and the indicator dilution method. In the indicator dilution technique, a known amount of a substance such as a dye or, more commonly, a radioactive isotope is injected into an arm vein and the concentration of the indicator in serial samples of arterial blood is determined. The output of the heart is equal to the amount of indicator injected divided by its average concentration in arterial blood after a single circulation through the heart.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.7
      Seconds

  • Question 4 - The postextrasystolic potentiation of myocardial contractility is due to: ...

    Incorrect

    • The postextrasystolic potentiation of myocardial contractility is due to:

      Your Answer: Increased myocardial fiber length

      Correct Answer: Increase in intracellular Ca2+

      Explanation:

      The postextrasystolic potentiation of myocardial contractility Is not due to ventricular filling. It occurs in isolated locations in the heart and is due to increase availability of intracellular calcium.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      97.3
      Seconds

  • Question 5 - Which of the following structures is not part of the conducting system of...

    Correct

    • Which of the following structures is not part of the conducting system of the heart?

      Your Answer: Ventricular wall

      Explanation:

      The conduction system of the heart consists of the SA node, AV node, internodal pathway between these two nodes, Bundle of His and the purkinje fibers

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      3.4
      Seconds

  • Question 6 - Most of the venous blood returns to the heart through the: ...

    Correct

    • Most of the venous blood returns to the heart through the:

      Your Answer: Coronary sinus and anterior cardiac veins

      Explanation:

      Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins which drain into the right atrium.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      2
      Seconds

  • Question 7 - 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
      3.5
      Seconds

  • Question 8 - 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
      17.2
      Seconds

  • Question 9 - Arterioles stemming from the coronary artery can also empty into the heart directly...

    Correct

    • Arterioles stemming from the coronary artery can also empty into the heart directly via the:

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      10.8
      Seconds

  • Question 10 - Cross-bridges between actin and myosin filaments contain: ...

    Correct

    • Cross-bridges between actin and myosin filaments contain:

      Your Answer: Calcium ions

      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 causes 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      3.1
      Seconds

  • Question 11 - Currents caused by opening of which of the following channels contribute to the...

    Correct

    • Currents caused by opening of which of the following channels contribute to the repolarization phase of the action potential of the ventricular muscle fibers?

      Your Answer: Potassium channels

      Explanation:

      Depolarization occurs due to opening of the voltage gated sodium channels. Repolarization occurs due to opening of the voltage gates potassium channels causing an out flux of potassium ions, decreasing the membrane potential towards resting potential.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      6.9
      Seconds

  • Question 12 - Regarding cardiac contractility, catecholamines exert their inotropic effect via: ...

    Correct

    • Regarding cardiac contractility, catecholamines exert their inotropic effect via:

      Your Answer: Î’1-adrenergic receptors and gs

      Explanation:

      Catecholamines exert their inotropic effect on the heart via the B1 adrenergic receptors and Gs, stimulating adenyl cyclase and increasing the production of cAMP.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      6.1
      Seconds

  • Question 13 - Activation of baroreceptor reflex involves: ...

    Correct

    • Activation of baroreceptor reflex involves:

      Your Answer: Short term regulation of systemic blood pressure

      Explanation:

      Baroreceptors are found in the heart and the blood vessels. They are the carotid sinus and the aortic arch receptors and respond to the minute to minute change in the blood pressure i.e. a change in the pulsatile pressure and not to a change in the mean arterial pressure. If the pulse pressure decreases, the rate of firing of the receptors decreases, stimulating an increase in the heart rate and blood pressure. Mechanisms that regulate the long term blood pressure control include the renin-angiotensin-aldosterone mechanism.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.9
      Seconds

  • Question 14 - 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
      3.5
      Seconds

  • Question 15 - 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
      1.2
      Seconds

  • Question 16 - In the blood supply of the heart, ‘dominance’ refers to the coronary artery...

    Correct

    • In the blood supply of the heart, ‘dominance’ refers to the coronary artery which supplies the?

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.9
      Seconds

  • Question 17 - Which of the following has the shortest duration: ...

    Correct

    • Which of the following has the shortest duration:

      Your Answer: Atrial systole

      Explanation:

      Atrial systole: 0.1s

      Atrial diastole: around 0.4s

      Ventricular diastole: 0.4-0.53s

      Ventricular systole: 0.27s

      PR interval: 0.12-0.2 s

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      3
      Seconds

  • Question 18 - Which is the commonest cardiovascular abnormality seen in an adult patient with Marfan’s...

    Correct

    • Which is the commonest cardiovascular abnormality seen in an adult patient with Marfan’s syndrome?

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      2.2
      Seconds

  • Question 19 - Which of the following antiarrhythmic drugs may be used in the treatment of...

    Correct

    • Which of the following antiarrhythmic drugs may be used in the treatment of long QT syndrome?

      Your Answer: Atenolol

      Explanation:

      Beta-blockers are the mainstay of treatment in long QT syndrome. Implantable cardioverter-defibrillators are the most effective treatment in genotypes with a high risk of recurrence.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      1.5
      Seconds

  • Question 20 - 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
      9
      Seconds

  • Question 21 - When the heart rate is increased (to pathological levels) which of the following...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      3.3
      Seconds

  • Question 22 - Catecholamines… ...

    Correct

    • Catecholamines…

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      5.1
      Seconds

  • Question 23 - The hyperpolarization phase of pacemaker cells is dominated by ____ current. ...

    Correct

    • The hyperpolarization phase of pacemaker cells is dominated by ____ current.

      Your 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4
      Seconds

  • Question 24 - 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
      5.8
      Seconds

  • Question 25 - The following is true in relation to coronary venous drainage? ...

    Correct

    • The following is true in relation to coronary venous drainage?

      Your Answer: Most venous return ultimately drains into right atrium via the coronary sinus

      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

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      9.7
      Seconds

  • Question 26 - What is the function of the BK channel on the vascular smooth muscle...

    Correct

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

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

      Explanation:

      BK channels, also known as large-conductance calcium-activated potassium channels, play a critical role in regulating vascular smooth muscle tone. When BK channels open, they allow a large efflux of potassium ions (K+) out of the cell. This efflux of K+ causes the membrane potential to become more negative (hyperpolarization), which in turn leads to the closure of voltage-gated calcium channels. The closure of these calcium channels reduces the influx of calcium ions (Ca2+) into the smooth muscle cells, resulting in decreased intracellular calcium levels and subsequent relaxation of the smooth muscle.

      Thus, BK channels promote smooth muscle relaxation by hyperpolarizing the membrane and reducing the activity of voltage-gated Ca2+ channels.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      1.4
      Seconds

  • Question 27 - Which of the following conditions has no effect on cardiac output? ...

    Correct

    • Which of the following conditions has no effect on cardiac output?

      Your Answer: Sleep

      Explanation:

      Sleep has no effect on the cardiac output. Anxiety, excitement and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      3.1
      Seconds

  • Question 28 - Which of the following factors serve to decrease cardiac output? ...

    Correct

    • Which of the following factors serve to decrease cardiac output?

      Your Answer: Standing from a lying position

      Explanation:

      Sleep has no effect on the cardiac output. Anxiety, excitement, increased body temperature and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      1.7
      Seconds

  • Question 29 - What is a characteristic findings on ECG in hyperkalaemia? ...

    Correct

    • What is a characteristic findings on ECG in hyperkalaemia?

      Your Answer: Tall, tented T waves

      Explanation:

      Hyperkalaemia leads to:

      – Prolonged PR interval

      – Small P waves

      – Tall, tented T waves

      – Widened QRS complexes and eventually asystole.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      1.4
      Seconds

  • Question 30 - All of the following are consistent with the indicator dilution method except--- ...

    Correct

    • All of the following are consistent with the indicator dilution method except---

      Your Answer: In thermodilution, the indicator used is warm saline

      Explanation:

      In thermodilution, the indicator used is cold saline.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.8
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular (29/30) 97%
Medicine (29/30) 97%
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