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  • Question 1 - Regarding the cardiac muscle striations as viewed under the microscope, which areas are...

    Incorrect

    • Regarding the cardiac muscle striations as viewed under the microscope, which areas are dark?

      Your Answer: H band and m line

      Correct Answer: A band and z line

      Explanation:

      Dark bands: a, h. Dark line: z. Clear band: i, m

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      7.9
      Seconds

  • Question 2 - The basic unit of contraction in myocytes is: ...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      5.3
      Seconds

  • Question 3 - 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
      23.8
      Seconds

  • Question 4 - Normal stroke volume is about: ...

    Correct

    • Normal stroke volume is about:

      Your Answer: 70 ml

      Explanation:

      Stroke volume is the amount of blood that is pumped from the heart into the aorta. It is typically 70 ml.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      42.7
      Seconds

  • Question 5 - Following an action potential, cytosolic Ca2+ is increased. The binding of free Ca2+...

    Incorrect

    • Following an action potential, cytosolic Ca2+ is increased. The binding of free Ca2+ to troponin C results in all of the following except:

      Your Answer: Inhibition of troponin i

      Correct Answer: Weakening of the troponin i interaction with actin

      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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      23.2
      Seconds

  • Question 6 - The direct determinants of cardiac output are ...

    Correct

    • The direct determinants of cardiac output are

      Your Answer: Stroke volume and heart rate

      Explanation:

      Cardiac output is classically defined alongside stroke volume (SV) and the heart rate (HR) as:Cardiac Output [L/min] = Stroke Volume [L/beat] x Heart Rate [beats/min]

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.1
      Seconds

  • Question 7 - What is pulse pressure? ...

    Correct

    • What is pulse pressure?

      Your Answer: Difference between systolic and diastolic pressure

      Explanation:

      The pulse pressure is the difference between the measured systolic and diastolic pressures.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.3
      Seconds

  • Question 8 - 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
      11.6
      Seconds

  • Question 9 - 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: Intestine

      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
      6.3
      Seconds

  • Question 10 - The isoforms of nitric oxide synthase which are found in the nervous system...

    Incorrect

    • 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: Po4

      Correct 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      42.4
      Seconds

  • Question 11 - Myocardial oxygen consumption is increased by: ...

    Correct

    • Myocardial oxygen consumption is increased by:

      Your Answer: An increase in after load

      Explanation:

      Cardiac oxygen consumption is directly related to the amount of tension that develops in the ventricles. It is increased by an increased size of heart, increased afterload, increased contractility and increased heart rate.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      27.9
      Seconds

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

    Incorrect

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

      Your Answer: Hormonal influences

      Correct 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
      4.8
      Seconds

  • Question 13 - All of the following are consistent with the indicator dilution method except--- ...

    Incorrect

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

      Your Answer: The indicator must have no haemodynamic effects

      Correct 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
      2.7
      Seconds

  • Question 14 - The principle by which the energy of contraction is proportional to the initial...

    Incorrect

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

      Your Answer: Indirect Fick method

      Correct 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
      8.9
      Seconds

  • Question 15 - The SA and AV nodes are usually supplied by which artery? ...

    Incorrect

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

      Your Answer: Circumflex artery

      Correct 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
      55
      Seconds

  • Question 16 - Transport of Ca2+ into the reticulum to initiate cardiac muscle relaxation in via:...

    Incorrect

    • Transport of Ca2+ into the reticulum to initiate cardiac muscle relaxation in via:

      Your Answer: Dihydropyridine receptors

      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).

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4
      Seconds

  • Question 17 - Although variable, branches of which artery most often supply the SA and AV...

    Incorrect

    • Although variable, branches of which artery most often supply the SA and AV nodes?

      Your Answer: Left coronary artery

      Correct Answer: Right coronary artery

      Explanation:

      The RCA (right coronary artery) supplies the SA and the AV nodes along with the postero-basal wall of the left ventricle, posterior one third of the inferior vena cava, right ventricle and the posteromedial papillary muscle in the left ventricle.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.3
      Seconds

  • Question 18 - Initial depolarization of cardiac muscle is due to influx of: ...

    Incorrect

    • Initial depolarization of cardiac muscle is due to influx of:

      Your Answer: Ca++

      Correct Answer: Na+

      Explanation:

      Initial depolarization of the cardiac muscle results from opening of the sodium voltage gated channels. This results in the influx of sodium and an increase in the membrane potential towards threshold. Potassium efflux results in repolarization.

      The cardiac action potential has 5 phases:

      • Phase 0—depolarization because of the opening of fast sodium channels. Potassium flux also decreases.
      • Phase 1—partial repolarization because of a rapid decrease in sodium ion passage as fast sodium channels close.
      • Phase 2—plateau phase in which the movement of calcium ions out of the cell, maintains depolarization.
      • Phase 3—repolarization, sodium, and calcium channels all close and membrane potential returns to baseline.
      • Phase 4—resting membrane potential (−90 mV), resulting from the activity of the Na+/K+ ATPase pump which creates a negative intracellular potential because of the exchange of three sodium ions for only two potassium ions.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      82.4
      Seconds

  • Question 19 - Which of the following causes an increase in venous return? ...

    Incorrect

    • Which of the following causes an increase in venous return?

      Your Answer: Positive intra-thoracic pressure

      Correct Answer: An increase in the negative intra-thoracic pressure

      Explanation:

      During inspiration, intrathoracic pressure becomes more negative and intra-abdominal pressure more positive. This increases the venous pressure gradient from abdomen to thorax and promotes filling of the central veins.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      15.1
      Seconds

  • Question 20 - Which of the following does not contribute to increased stroke volume during exercise?...

    Incorrect

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      6.6
      Seconds

  • Question 21 - In a 30 year old male with hypertrophic obstructive cardiomyopathy (HOCM), which of...

    Correct

    • In a 30 year old male with hypertrophic obstructive cardiomyopathy (HOCM), which of the following is not associated with increased risk of sudden death?

      Your Answer: Age

      Explanation:

      Hypertrophic cardiomyopathy (HCM) is a disease in which a portion of the myocardium (heart muscle) is enlarged without any obvious cause, creating functional impairment of the heart. It is the leading cause of sudden death in young athletes. The major risk factors for sudden death (SD) are recent unexplained syncope unlikely to be neurocardiogenic; HCM-related SD in first-degree or other close relatives; repetitive and/or prolonged nonsustained ventricular tachycardia (NSVT) episodes on Holter or extended ambulatory monitoring; massive left ventricular hypertrophy (LVH) (wall thickness ≥30 mm); extensive/diffuse late gadolinium enhancement (LGE); end-stage heart failure usually with systolic dysfunction; and thin-walled akinetic LV apical aneurysm with regional scarring.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      5.7
      Seconds

  • Question 22 - Calcium induced calcium release occurs in the sarcoplasmic reticulum by activation of which...

    Incorrect

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

      Your Answer: Beta receptors

      Correct 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
      9.1
      Seconds

  • Question 23 - Stimulation of the carotid sinus results in: ...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.1
      Seconds

  • Question 24 - Myocardium requires more oxygen to expel blood in: ...

    Correct

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      955.5
      Seconds

  • Question 25 - Which one of the following ECG findings is least associated with digoxin use?...

    Incorrect

    • 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.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.7
      Seconds

  • Question 26 - The T-tubular system in cardiac muscle is: ...

    Incorrect

    • The T-tubular system in cardiac muscle is:

      Your Answer: Integral to the maintenance of cytoskeletal integrity of the cell

      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
      9.1
      Seconds

  • Question 27 - The following products of the vascular endothelium produce vasodilation except: ...

    Incorrect

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

      Your Answer: Prostacyclin

      Correct 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
      9.6
      Seconds

  • Question 28 - Direct conduction from the atrium to the ventricles is prevented by: ...

    Incorrect

    • Direct conduction from the atrium to the ventricles is prevented by:

      Your Answer: Bundle of his

      Correct Answer: Annulus fibrosus

      Explanation:

      The annulus fibrosus disconnects the syncytium complex. The atria are rapidly activated however the activation peters out when the insulating layer-the annulus fibrosus-is reached.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      11
      Seconds

  • Question 29 - Cross-bridges between actin and myosin filaments contain: ...

    Incorrect

    • Cross-bridges between actin and myosin filaments contain:

      Your Answer:

      Correct 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
      0
      Seconds

  • Question 30 - Regarding cardiac contractility, catecholamines exert their inotropic effect via: ...

    Incorrect

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

      Your Answer:

      Correct Answer: Β1-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
      0
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular (19/28) 68%
Medicine (19/28) 68%
Passmed
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