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  • Question 1 - Heart rate can be slowed by: ...

    Incorrect

    • Heart rate can be slowed by:

      Your Answer: Hypoxia

      Correct Answer: Grief

      Explanation:

      Grief stimulates the parasympathetic nervous system, resulting in a decrease in the heart rate.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      29.6
      Seconds
  • Question 2 - The following determines the strength of contraction ...

    Incorrect

    • The following determines the strength of contraction

      Your Answer: None of the above

      Correct Answer: Plateau phase

      Explanation:

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

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      19.2
      Seconds
  • Question 3 - Coronary flow is reduced during ...

    Correct

    • Coronary flow is reduced during

      Your 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
      13.8
      Seconds
  • Question 4 - Which of the following phases in depolarization and repolarization of cardiac muscle cells...

    Incorrect

    • Which of the following phases in depolarization and repolarization of cardiac muscle cells are caused by the inactivation of Na+ channels?

      Your Answer: Phase 4 : slow repolarization process

      Correct Answer: Phase 1 : rapid repolarization

      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
      34.9
      Seconds
  • Question 5 - Afferent fibers from the baroreceptors of the great arteries form branches of which...

    Correct

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

      Your Answer: Glossopharyngeal and vagus nerves

      Explanation:

      The receptors of the carotid sinus are innervated by the carotid sinus nerve, a branch of the glossopharyngeal nerve. The aortic arch receptors located in the arch of the aorta are innervated by the aortic depressor nerve, a branch of the vagus nerve.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      59.9
      Seconds
  • Question 6 - 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
      72.3
      Seconds
  • Question 7 - What are the diagnostic criteria for an ST segment elevation type of acute...

    Correct

    • What are the diagnostic criteria for an ST segment elevation type of acute myocardial infarction?

      Your Answer: 1 mm ST elevation in 2 limb leads

      Explanation:

      The current guidelines for the ECG diagnosis of the ST segment elevation type of acute myocardial infarction require at least 1 mm (0.1 mV) of ST segment elevation in the limb leads, and at least 2 mm elevation in the precordial leads. These elevations must be present in anatomically contiguous leads. (I, aVL, V5, V6 correspond to the lateral wall; V3-V4 correspond to the anterior wall ; V1-V2 correspond to the septal wall; II, III, aVF correspond to the inferior wall.)

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      18.4
      Seconds
  • Question 8 - Angina pectoris develops when blood through the coronary artery becomes: ...

    Correct

    • Angina pectoris develops when blood through the coronary artery becomes:

      Your Answer: Restricted, limiting blood blow

      Explanation:

      Angina pectoris develops when stenosis ( >70%) of the artery occurs as a result of formation of an atherosclerotic plaque. This leads to a decrease in the O2 carried to the thickened heart muscle by the blood, leading to the characteristic chest pain associated with angina pectoris.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      19.6
      Seconds
  • Question 9 - Describe the location of the SA node: ...

    Correct

    • Describe the location of the SA node:

      Your Answer: Junction of the SVC and right atrium

      Explanation:

      Anatomically the SA node is located at the junction of the superior vena cava and the right atrium.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      21.2
      Seconds
  • Question 10 - Regarding blood supply to the heart; ...

    Correct

    • Regarding blood supply to the heart;

      Your Answer: Coronary arteries fill as the heart relaxes

      Explanation:

      The heart muscles acts like the skeletal muscle in the fact that it also compress the vessels during contraction. As the pressure in the ventricle is slightly greater than in the aorta the coronary vessels collapse during systole. Blood flows through them during the diastole phase of contraction.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      29.5
      Seconds
  • Question 11 - Activation of nitric oxide synthesis by endothelial cells is triggered by: ...

    Incorrect

    • Activation of nitric oxide synthesis by endothelial cells is triggered by:

      Your Answer: Acetylcholine

      Correct Answer: All of the above

      Explanation:

      Acetylcholine, histamine, bradykinin, vasoactive intestinal peptide (VIP) and shear stress on the endothelial cells causing the release of NO. NO is formed from arginine and causes vasodilatation of the blood vessels.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      23.6
      Seconds
  • Question 12 - The ‘c’ wave in JVP corresponds more closely with: ...

    Incorrect

    • The ‘c’ wave in JVP corresponds more closely with:

      Your Answer: Non-isovolumetric contraction

      Correct Answer: Isovolumetric contraction

      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
      254.5
      Seconds
  • Question 13 - Which of the following occurs during a Valsalva manoeuvre? ...

    Incorrect

    • Which of the following occurs during a Valsalva manoeuvre?

      Your Answer: Forced inspiration against a closed glottis: no: forced expiration rather

      Correct Answer: An initial rise in blood pressure

      Explanation:

      The Valsalva maneuver involves forced expiration against a closed glottis. It has several phases, each affecting the cardiovascular system differently:

      1. Phase I: During the initial forced expiration against the closed glottis, there is a transient rise in intrathoracic pressure, which compresses the thoracic aorta and causes a brief increase in blood pressure.
      2. Phase II: Continued straining leads to decreased venous return to the heart, reducing cardiac output and causing a drop in blood pressure. This phase is characterized by a compensatory increase in heart rate.
      3. Phase III: Upon releasing the strain, there is a sudden drop in intrathoracic pressure, which momentarily decreases blood pressure.
      4. Phase IV: Blood pressure then rises rapidly as venous return to the heart is restored, leading to increased cardiac output. This is often followed by a reflex bradycardia (slow heart rate).

      Given these phases, the most accurate statement about what occurs during the Valsalva maneuver is the initial rise in blood pressure (Phase I).

      Other options explained:

      • Forced inspiration against a closed glottis: Incorrect. The Valsalva maneuver involves forced expiration, not inspiration, against a closed glottis.
      • Low intrathoracic pressures throughout: Incorrect. The Valsalva maneuver involves high intrathoracic pressures due to forced expiration.
      • Disruption of autonomic function: Incorrect. The Valsalva maneuver affects autonomic function but does not disrupt it. Instead, it triggers autonomic responses to changes in blood pressure and heart rate.
      • No change: Incorrect. The Valsalva maneuver causes significant changes in blood pressure and heart rate.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      99.2
      Seconds
  • Question 14 - 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
      35.6
      Seconds
  • Question 15 - Stimulation of the carotid sinus results in: ...

    Incorrect

    • Stimulation of the carotid sinus results in:

      Your Answer: Thirst

      Correct 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
      13.3
      Seconds
  • Question 16 - Which factor produced by the endothelium is responsible for the regulation of vascular...

    Correct

    • Which factor produced by the endothelium is responsible for the regulation of vascular cell growth?

      Your Answer: Vascular endothelial growth factor (VEGF)

      Explanation:

      VEGF is produced by the endothelial cells and is the major growth factor responsible for causing vasculogenesis. Some isoforms of this growth factor also have a prominent role in formation of lymphatic vessels.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      16.3
      Seconds
  • Question 17 - Calcium needed for cardiac muscle contraction is made available during which phase of...

    Correct

    • Calcium needed for cardiac muscle contraction is made available during which phase of the action potential?

      Your Answer: 2

      Explanation:

      It is made available during the plateau phase of the action potential i.e. phase 2. During the plateau phase of the action potential, Calcium from the extracellular fluid enters through the L type of calcium channels. This entry triggers the release of more calcium from the sarcoplasmic reticulum via the ryanodine receptors.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      58
      Seconds
  • Question 18 - The interventricular septum is supplied anteriorly by the? ...

    Incorrect

    • The interventricular septum is supplied anteriorly by the?

      Your Answer: Marginal branch of the right coronary artery

      Correct Answer: Left anterior descending artery

      Explanation:

      The anterior interventricular artery or left anterior descending artery supplies the anterior 2/3rds of the interventricular septum.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      18.4
      Seconds
  • Question 19 - 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
      28.5
      Seconds
  • Question 20 - 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
      10.6
      Seconds
  • Question 21 - The areas of extensive series of sarcoplasmic folds known as intercalated discs always...

    Correct

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

      Your 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
      39.4
      Seconds
  • Question 22 - What is the most common cardiac defect seen in patients with Down’s syndrome?...

    Correct

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

      Your Answer: Atrioventricular septal defect

      Explanation:

      The rate of congenital heart disease in new-borns with Down syndrome is around 40%. Of those with heart disease, about 80% have an atrioventricular septal defect or ventricular septal defect with the former being more common. Mitral valve problems become common as people age, even in those without heart problems at birth.[3] Other problems that may occur include tetralogy of Fallot and patent ductus arteriosus.[38] People with Down syndrome have a lower risk of hardening of the arteries

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      17.4
      Seconds
  • Question 23 - 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
      21.6
      Seconds
  • Question 24 - 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
      10.9
      Seconds
  • Question 25 - Which of the following is NOT an effect of a positive inotropic agent...

    Incorrect

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

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

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

      Explanation:

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

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      92
      Seconds
  • Question 26 - In Jugular vein pressure the “a” wave represents? ...

    Correct

    • In Jugular vein pressure the “a” wave represents?

      Your Answer: Atrial systole

      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 and two downward deflections 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
      13.9
      Seconds
  • Question 27 - 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
      11.8
      Seconds
  • Question 28 - Which of the following has the shortest duration: ...

    Incorrect

    • Which of the following has the shortest duration:

      Your Answer: Ventricular systole

      Correct 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
      30
      Seconds
  • Question 29 - In a normal heart rate at rest, the left ventricular end-diastolic volume is...

    Incorrect

    • In a normal heart rate at rest, the left ventricular end-diastolic volume is ….

      Your Answer: 10-30 ml

      Correct Answer: 100-130 ml

      Explanation:

      In cardiovascular physiology, end-diastolic volume (EDV) is the volume of blood in the right and/or left ventricle at end load or filling in (diastole) or the amount of blood in the ventricles just before systole. Because greater EDVs cause greater distention of the ventricle, EDV is often used synonymously with preload, which refers to the length of the sarcomeres in cardiac muscle prior to contraction (systole). End-diastolic volume: Right = 144 mL(± 23mL) & Left = 142 mL (± 21 mL).

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      35.7
      Seconds
  • Question 30 - Nitric oxide triggers vascular smooth muscle contraction through activation of which enzyme? ...

    Incorrect

    • Nitric oxide triggers vascular smooth muscle contraction through activation of which enzyme?

      Your Answer: Protein kinase a

      Correct Answer: Guanylyl cyclase

      Explanation:

      Impaired production or excess catabolism of NO impairs this endothelium-dependent vasodilator function and may contribute to excessive vasoconstriction under various pathological situations.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      56.9
      Seconds
  • Question 31 - The following contributes to the rate of depolarization? ...

    Correct

    • The following contributes to the rate of depolarization?

      Your Answer: All of the options given

      Explanation:

      Depolarization occurs due to impulses generated by the SA node. As the heart beats to the rhythm of the SA node, certain factors will effect the rate of depolarization. All the mentioned options effect the rate of depolarization.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      14.5
      Seconds
  • Question 32 - Depolarization spreads rapidly through cardiac muscle fibers because of the presence of: ...

    Incorrect

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

      Your Answer: Desmosomes

      Correct 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
      9.3
      Seconds
  • Question 33 - Which of the following components regulate cardiac output? ...

    Incorrect

    • Which of the following components regulate cardiac output?

      Your Answer: Afterload and preload

      Correct Answer: All of the above

      Explanation:

      Cardiac output is regulated by the autonomic nervous system with sympathetic nerves having a positive chronotropic and inotropic effect and parasympathetic nerves having the opposite effect. An increase in preload will increase cardiac output likewise an afterload increase will also increase cardiac output.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      10.1
      Seconds
  • Question 34 - The T-tubular system in cardiac muscle is: ...

    Incorrect

    • The T-tubular system in cardiac muscle is:

      Your Answer: Located at the junction of the a and i zones

      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
      59.9
      Seconds
  • Question 35 - Blood flow to the subendocardial portions of the left ventricular muscle occurs mainly...

    Correct

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

      Your 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
      31.1
      Seconds
  • Question 36 - What is the main reason for checking the urea and electrolytes prior to...

    Incorrect

    • What is the main reason for checking the urea and electrolytes prior to commencing a patient on amiodarone?

      Your Answer: To detect hyperkalaemia

      Correct Answer: To detect hypokalaemia

      Explanation:

      All antiarrhythmic drugs have the potential to cause arrhythmias. Coexistent hypokalaemia significantly increases this risk.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      13.2
      Seconds
  • Question 37 - 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
      8.3
      Seconds
  • Question 38 - Myocardial fibers have a resting membrane potential of approximately: ...

    Incorrect

    • Myocardial fibers have a resting membrane potential of approximately:

      Your Answer: -60mv

      Correct 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
      8.8
      Seconds
  • Question 39 - Hyperkalaemia [K+ =7meq/l] can lead to the following ECG changes [Ca++ normal] ...

    Incorrect

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

      Your Answer: QRS lengthened

      Correct 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
      42.6
      Seconds
  • Question 40 - If both the noradrenergic and the cholinergic systems are blocked in the heart,...

    Incorrect

    • If both the noradrenergic and the cholinergic systems are blocked in the heart, the rate will be approximately:

      Your Answer: 50/ min

      Correct Answer: 100/min

      Explanation:

      The normal heart beat is about 70/min. This is due to a predominant parasympathetic activity. If sympathetic activity was unopposed the heart rate would have been 150/min. When both the noradrenergic and cholinergic systems are blocked the heart rate is 100/min. This is the normal firing rate of the SA node.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      14.6
      Seconds
  • Question 41 - Which factors increase the end-diastolic volume? ...

    Correct

    • Which factors increase the end-diastolic volume?

      Your Answer: Constriction of veins

      Explanation:

      End diastolic volume is also known as preload. It is the amount of blood the heart contracts against. Constriction of veins will decrease venous pooling and increase venous return, hence increasing the end diastolic volume. Standing will increase venous pooling hence decreasing venous return and end diastolic volume. Raised intrapericardial pressure will also decrease venous return and hence end diastolic volume.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      52.6
      Seconds
  • Question 42 - 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: Initiates Ca2+ release from the sarcoplasmic reticulum

      Correct 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
      78.4
      Seconds
  • Question 43 - 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
      106.8
      Seconds
  • Question 44 - 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: Formation of myosin/troponin i cross-bridges

      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
      34.3
      Seconds
  • Question 45 - Concerning surface anatomy, where is the base of the heart ...

    Incorrect

    • Concerning surface anatomy, where is the base of the heart

      Your Answer: 5th intercostal space mid clavicular line

      Correct Answer: 2nd left costal to 3rd right costal cartilage

      Explanation:

      The base of the heart, also known as the superior border of the heart corresponds to a line connecting the inferior border of the 2nd left costal cartilage to the superior border of the 3rd right costal cartilage.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      8.4
      Seconds
  • Question 46 - Impulse conduction through the AV node is slow and depends on the action...

    Incorrect

    • Impulse conduction through the AV node is slow and depends on the action potential produced by which of the following.

      Your Answer: All of the above

      Correct Answer: Calcium flux

      Explanation:

      The action potentials in the SA and AV nodes are largely due to Ca2+, with no contribution by Na+ influx.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      19.5
      Seconds
  • Question 47 - The steps of cardiac cycle in sequence are: ...

    Incorrect

    • The steps of cardiac cycle in sequence are:

      Your Answer: Ejection, isovolumetric relaxation, passive ventricular filling, isovolumetric contraction, active 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
      24.5
      Seconds
  • Question 48 - Which part of the ECG represents ventricular repolarisation? ...

    Correct

    • Which part of the ECG represents ventricular repolarisation?

      Your Answer: T wave

      Explanation:

      Ventricular repolarisation is denoted by the T wave.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      8.7
      Seconds
  • Question 49 - The major factor in controlling coronary artery blood flow is considered to be?...

    Incorrect

    • The major factor in controlling coronary artery blood flow is considered to be?

      Your Answer: Parasympathetic input

      Correct Answer: Metabolites of oxygen consumption

      Explanation:

      There is a strong relationship between myocardial blood flow and oxygen consumption. This indicates that products of metabolism may cause vasodilation of the coronary artery.

    • This question is part of the following fields:

      • Cardiovascular
      • Medicine
      12.1
      Seconds
  • Question 50 - 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
      17.5
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular (23/50) 46%
Medicine (23/50) 46%
Passmed