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  • Question 1 - What is troponin? ...

    Incorrect

    • What is troponin?

      Your Answer: A myosin light chain

      Correct Answer: A component of thin filaments

      Explanation:

      Skeletal muscle cytoplasmic proteins include myosin and actin (also known as thick and thin filaments, respectively) which are arranged in a repeating unit called a sarcomere. Troponin is a component of thin filaments (along with tropomyosin), and is the protein to which calcium binds.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      15.3
      Seconds

  • Question 2 - When observing a JVP, which of the following would lead to prominent v...

    Correct

    • When observing a JVP, which of the following would lead to prominent v waves?

      Your Answer: Tricuspid regurgitation

      Explanation:

      The v wave corresponds to Venous filling when the tricuspid valve is closed and venous pressure increases from venous return. In Tricuspid regurgitation there is additional blood from the regurgitant flow and thus this leads to a more prominent V wave.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      30.5
      Seconds

  • Question 3 - Which coronary artery supplies the right atria? ...

    Correct

    • Which coronary artery supplies the right atria?

      Your Answer: Right coronary

      Explanation:

      The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum. The circumflex artery arises from the left coronary artery and follows the coronary sulcus to the left. Eventually, it will fuse with the small branches of the right coronary artery. The right coronary artery proceeds along the coronary sulcus and distributes blood to the right atrium, portions of both ventricles, and the heart conduction system.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      22.1
      Seconds

  • Question 4 - The isoforms of nitric oxide synthase which are found in the nervous system...

    Correct

    • The isoforms of nitric oxide synthase which are found in the nervous system (NOS1) and endothelial cells (NOS3) are activated by agents that increase which of the following intracellular electrolytes?

      Your Answer: Ca

      Explanation:

      Synthesis of nitric oxide is stimulated by activation of the NMDA receptors by certain agents. This leads to opening of the Calcium channels and an influx of calcium into the cell. This will activate the nitric oxide synthase. Nitric oxide is produced on demand.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      23.9
      Seconds

  • Question 5 - The steps of cardiac cycle in sequence are: ...

    Incorrect

    • The steps of cardiac cycle in sequence are:

      Your Answer: Isovolumic contraction, ejection, isovolumic relaxation, active ventricular filling, passive ventricular filling.

      Correct Answer: Isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling.

      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.1st stage: diastole, or passive filling 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. 2nd stage: atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle (active filling).3rd stage: isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. 4th stage: ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. 5th 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
      51.2
      Seconds

  • Question 6 - 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 relaxation

      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
      9.5
      Seconds

  • Question 7 - Which of the following is NOT true of the parasympathetic control of the...

    Incorrect

    • Which of the following is NOT true of the parasympathetic control of the heart?

      Your Answer: It decreases heart rate via the SA node

      Correct Answer: It can be blocked by beta blockers

      Explanation:

      Parasympathetic fibers do not innervate the Beta receptors on the heart. They are innervated by the sympathetic nerve fibers. Then a beta blocker such as propranolol will block the sympathetic outflow and increase the parasympathetic tone of the heart.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      37.8
      Seconds

  • Question 8 - Which of the following is first to rise following myocardial infarction? ...

    Correct

    • Which of the following is first to rise following myocardial infarction?

      Your Answer: Myoglobin

      Explanation:

      Myoglobin, is a sensitive indicator of muscle injury and is first to rise following MI within two hours but is nonspecific.Troponin and CK-MB both begin to rise approximately three hours after MI. The cardiac troponins T and I which are released within 4–6 hours of an attack of MI and remain elevated for up to 2 weeks, have nearly complete tissue specificity and are now the preferred markers for assessing myocardial damage.Lactate dehydrogenase (LDH) begins to rise approximately 12 hours after MI.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      6.5
      Seconds

  • Question 9 - 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
      4.4
      Seconds

  • Question 10 - How many molecules of myosin attach to actin at any given time? ...

    Incorrect

    • How many molecules of myosin attach to actin at any given time?

      Your Answer: 4

      Correct Answer: 1

      Explanation:

      1 molecule of myosin binds to actin at any give time.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      3.8
      Seconds

  • Question 11 - 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
      6.4
      Seconds

  • Question 12 - Depolarization of the T tubule membrane activates the sarcoplasmic reticulum via which receptors?...

    Incorrect

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

      Your Answer: Ryanodine receptors

      Correct 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
      8.7
      Seconds

  • Question 13 - Which of the following is true with AV nodal delay? ...

    Correct

    • Which of the following is true with AV nodal delay?

      Your Answer: Shortened by sympathetic stimulation

      Explanation:

      AV nodal delay Is about 0.1s before the action potential spreads to the ventricles. It is shortened by stimulation of the sympathetic nervous system and lengthened by stimulation of the parasympathetic system.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      38.9
      Seconds

  • Question 14 - Pacemaker cells in the SA node and the AV node are connected by?...

    Correct

    • Pacemaker cells in the SA node and the AV node are connected by?

      Your Answer: Gap junctions

      Explanation:

      Gap junctions allows for rapid propagation of the action potential from one cell to the other. The cells of the heart are connected by gap junctions.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      5.2
      Seconds

  • Question 15 - All valves are closed in which phase of the cardiac cycle? ...

    Incorrect

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

      Your Answer: None of the above

      Correct 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
      35.1
      Seconds

  • Question 16 - 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
      52.5
      Seconds

  • Question 17 - The right border of the heart corresponds to which line on the surface...

    Correct

    • The right border of the heart corresponds to which line on the surface of the chest?

      Your Answer: Line drawn from the 3rd right costal cartilage to the 6th right costal cartilage

      Explanation:

      The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      26.5
      Seconds

  • Question 18 - Which of the following corresponds to an oblique line drawn from the sternal...

    Incorrect

    • Which of the following corresponds to an oblique line drawn from the sternal end of the left 3rd costal cartilage to the sternal end of the right 6th costal cartilage?

      Your Answer: Aortic arch

      Correct Answer: Atrio-ventricular (coronary) groove

      Explanation:

      The AV groove corresponds to the right border of the heart. The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      22.5
      Seconds

  • Question 19 - Cholinergic vagal supply to the SA and AV nodes results in slowing of...

    Incorrect

    • Cholinergic vagal supply to the SA and AV nodes results in slowing of the heart rate via:

      Your Answer: B1 receptors

      Correct Answer: M2 muscarinic receptors

      Explanation:

      M2 muscarinic receptors are the receptors for the parasympathetic system to the SA and the AV node.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      20.6
      Seconds

  • Question 20 - Which of the following is NOT associated with the development of aortic regurgitation?...

    Incorrect

    • Which of the following is NOT associated with the development of aortic regurgitation?

      Your Answer: Bechet's disease

      Correct Answer: Dilated cardiomyopathy

      Explanation:

      Aortic insufficiency, is often due to the aortic root dilation, which is idiopathic in over 80% of cases, but otherwise may result from aging, syphilitic aortitis, osteogenesis imperfecta, aortic dissection, Bechet’s disease, reactive arthritis and systemic hypertension. Additionally, aortic insufficiency has been linked to the use of some medications and other potential causes that affect the valve directly including Marfan’s syndrome, Ehlers–Danlos syndrome, ankylosing spondylitis, and systemic lupus erythematosus. In acute cases of aortic insufficiency, the main causes are infective endocarditis, aortic dissection or trauma. Dilated cardiomyopathy is associated with the development of mitral regurgitation, not aortic regurgitation

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.7
      Seconds

  • Question 21 - Which of the following are responsible for the 4th heart sound? ...

    Incorrect

    • Which of the following are responsible for the 4th heart sound?

      Your Answer: Rapid ventricular filling

      Correct Answer: Ventricular hypertrophy

      Explanation:

      The fourth heart sound is not normally audible in a normal adult. It occurs as a consequence of ventricular hypertrophy. It is caused by filling of the ventricle in atrial systole.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      14.8
      Seconds

  • Question 22 - Vasodilatation of coronary arteries is caused by: ...

    Incorrect

    • Vasodilatation of coronary arteries is caused by:

      Your Answer: None of options provided

      Correct 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
      24.9
      Seconds

  • Question 23 - The rate of depolarization of the SA node membrane potential is modulated by...

    Incorrect

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

      Your Answer: Autonomic tone

      Correct 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
      9.4
      Seconds

  • Question 24 - In the jugular venous pressure wave… ...

    Correct

    • In the jugular venous pressure wave…

      Your 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
      16.9
      Seconds

  • Question 25 - Which ion channel does not contribute to the myocardial action potential? ...

    Incorrect

    • Which ion channel does not contribute to the myocardial action potential?

      Your Answer: Delayed rectifier potassium channel

      Correct 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
      18.5
      Seconds

  • Question 26 - The basic unit of contraction in myocytes is: ...

    Incorrect

    • The basic unit of contraction in myocytes is:

      Your Answer: Actin

      Correct 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
      5.1
      Seconds

  • Question 27 - During which phase of the cardiac cycle does most of the ventricular filling...

    Incorrect

    • During which phase of the cardiac cycle does most of the ventricular filling occur?

      Your Answer: Isovolumetric ventricular relaxation

      Correct Answer: Ventricular diastole

      Explanation:

      During the phase of ventricular diastole when the heart muscle relaxes and all the valves are open, blood flows easily into the heart. This is the phase of rapid ventricular filling. During isovolumetric contraction and relaxation the volume of blood in the heart does not change. During ventricular ejection blood enters into the aorta and pulmonary vessels.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      17.1
      Seconds

  • Question 28 - Which one of the following is a cause of a soft second heart...

    Incorrect

    • Which one of the following is a cause of a soft second heart sound?

      Your Answer: Aortic regurgitation

      Correct Answer: Aortic stenosis

      Explanation:

      Second heart sound (S2) forms the dub of lub-dub and is composed of components A2 and P2. •    loud: hypertension•    soft: AS•    fixed split: physiological split (normally occurs during inhalation), right bundle branch block, pulmonary stenosis, and atrial septal defect.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      34
      Seconds

  • Question 29 - The internodal tract of Bachman: ...

    Incorrect

    • The internodal tract of Bachman:

      Your Answer: Its main function is to reduce the amount of conduction to the AV node

      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
      20.4
      Seconds

  • Question 30 - Stroke volume in a average sized man lying in supine position is about?...

    Incorrect

    • Stroke volume in a average sized man lying in supine position is about?

      Your Answer: 5l/min

      Correct Answer: 70 ml

      Explanation:

      The stroke volume of an average sized man who is lying is the supine position is about 70 ml.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      4.1
      Seconds

  • Question 31 - The a-wave is created by: ...

    Incorrect

    • The a-wave is created by:

      Your Answer: Rise in atrial pressure before the tricuspid valve opens

      Correct 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
      6.2
      Seconds

  • Question 32 - According to Starling's law of the heart: ...

    Correct

    • According to Starling's law of the heart:

      Your Answer: The extent of the preload is proportional to the end-diastolic volume

      Explanation:

      Frank starlings law 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 increased 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 the development of tension in the muscle fiber. The greater the venous return the greater the cardiac output. This relationship is directly proportional.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      25.5
      Seconds

  • Question 33 - The areas of extensive series of sarcoplasmic folds known as intercalated discs always...

    Incorrect

    • The areas of extensive series of sarcoplasmic folds known as intercalated discs always occur at what portion of the muscle fiber?

      Your Answer: A band

      Correct Answer: Z lines

      Explanation:

      The muscle fibers of the heart branch and interdigitate, but one complete unit is surrounded by a cell membrane. The place where one muscle fiber abuts the other, the cell membrane of both the fibers run parallel to each other through a series of extensive folds. These areas always occur on the Z lines and are known as intercalated discs.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      21.9
      Seconds

  • Question 34 - 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 stroke volume

      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
      13.9
      Seconds

  • Question 35 - The heart rate can be accelerated by: ...

    Incorrect

    • The heart rate can be accelerated by:

      Your Answer: Fever and increased intra-cranial pressure

      Correct Answer: Exercise and thyroid hormones

      Explanation:

      The firing of the SA node will increase due to exercises and as the thyroid hormone has a chronotropic effect on the heart, it too will result in an increase in the heart rate via stimulation of the adrenergic receptors of the heart. As during exercise the sympathetic nervous system is activated, it will directly have an positive chronotropic effect on the heart.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      22.8
      Seconds

  • Question 36 - Concerning surface anatomy, where is the aortic valve found? ...

    Incorrect

    • Concerning surface anatomy, where is the aortic valve found?

      Your Answer: Situated in the right second intercostal space underneath the sternum

      Correct Answer: Situated in the left third intercostal space underneath the sternum

      Explanation:

      The aortic valve is situated in the left 3rd intercostal space just beneath the sternum.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      17.7
      Seconds

  • Question 37 - The following is true in relation to coronary venous drainage? ...

    Incorrect

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

      Your Answer: Only the small veins drain into the coronary sinus

      Correct 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
      19.1
      Seconds

  • Question 38 - 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
      4.4
      Seconds

  • Question 39 - 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
      6.5
      Seconds

  • Question 40 - 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
      15.4
      Seconds

  • Question 41 - Initial depolarization of cardiac muscle is due to influx of: ...

    Correct

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

      Your 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
      18.5
      Seconds

  • Question 42 - Select the correct statement regarding the 4th heart sound, it? ...

    Incorrect

    • Select the correct statement regarding the 4th heart sound, it?

      Your Answer: Occurs after the second heart sound.

      Correct Answer: Can be heard in atrial systole.

      Explanation:

      The fourth heart sound is not normally audible in a normal adult. It occurs as a consequence of ventricular hypertrophy. It is caused by filling of the ventricle by atrial systole.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      26.1
      Seconds

  • Question 43 - Coronary blood flow occurs in? ...

    Correct

    • Coronary blood flow occurs in?

      Your Answer: Diastole

      Explanation:

      Coronary arteries are unique in that they fill during diastole, when not occluded by valve cusps nor compressed by myocardial contraction).

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      30.3
      Seconds

  • Question 44 - AV valves open during? ...

    Incorrect

    • AV valves open during?

      Your Answer: Isovolumetric contraction of ventricles

      Correct Answer: Early diastole

      Explanation:

      The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat, and so includes the diastole, the systole, and the intervening pause.The first stage, diastole, is when the semilunar valves (the pulmonary valve and the aortic valve) close, the atrioventricular (AV) valves (the mitral valve and the tricuspid valve) open, and the whole heart is relaxed. The second stage, atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle.The third stage, isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. The fourth stage, ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. During the fifth stage, isovolumic relaxation time, pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      16.3
      Seconds

  • Question 45 - 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
      4.9
      Seconds

  • Question 46 - Concerning surface anatomy, where is the mitral valve found? ...

    Correct

    • Concerning surface anatomy, where is the mitral valve found?

      Your Answer: Situated in the 4th intercostal space to the left of the sternum

      Explanation:

      The mitral valve is situated in the left 4th intercostal space just beneath the sternum.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      21.3
      Seconds

  • Question 47 - 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
      7.4
      Seconds

  • Question 48 - A sarcomere is the area between: ...

    Correct

    • A sarcomere is the area between:

      Your Answer: Two adjacent z lines

      Explanation:

      The area that lies between the two adjacent Z lines is known as a sarcomere and is the contractile unit of the muscle. The line passing in the middle of the myosin filaments is the M line. It also passes through the middle of the sarcomere.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      3.6
      Seconds

  • Question 49 - Hyperkalaemia [K+ =7meq/l] can lead to the following ECG changes [Ca++ normal] ...

    Correct

    • Hyperkalaemia [K+ =7meq/l] can lead to the following ECG changes [Ca++ normal]

      Your Answer: Peaked T waves

      Explanation:

      Hyperkalaemia causes the formation of tall tented T waves due to altered repolarization.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      18.3
      Seconds

  • Question 50 - 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
      2.3
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular (21/50) 42%
Medicine (21/50) 42%
Passmed
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