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Question 1
Incorrect
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Question 2
Incorrect
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Which of the following affects the magnitude of the action potential?
Your Answer: Extracellular Na+/K+ ratio
Correct Answer: Changes in the external Na+ concentration
Explanation:The magnitude of the action potential is determined by the sodium current. Increase in external sodium will result in increased influx of sodium and hence generation of a stronger action potential.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 3
Correct
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 4
Incorrect
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Which of the following structures of the cardiac conduction system is located in the right posterior portion of the interatrial septum?
Your Answer: Purkinje system
Correct Answer: AV node
Explanation:AV node is located at the right posterior portion of the interatrial septum.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 5
Correct
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Question 6
Incorrect
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Dicrotic notch is produced by which valves?
Your Answer: Mitral and pulmonary
Correct Answer: Aortic
Explanation:The graph of aortic pressure throughout the cardiac cycle displays a small dip (the incisure or dicrotic notch) which coincides with the aortic valve closure. The dip in the graph is immediately followed by a brief rise (the dicrotic wave) then gradual decline.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 7
Incorrect
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Although variable, branches of which artery most often supply the SA and AV nodes?
Your Answer: Left anterior descending 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 8
Incorrect
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What is the most common cardiac defect seen in patients with Down’s syndrome?
Your Answer: Patent ductus arteriosus
Correct 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
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 9
Correct
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Which of the following does not lower ventricular rate in atrial fibrillation?
Your Answer: Adrenaline
Explanation:Adrenaline is a sympathetic neurotransmitter which increases the heart rate. During atrial fibrillation the atria is contracting at more than 200 beats/min. Acetylcholine is a parasympathetic neurotransmitter decreasing the heart rate. Digital also depresses the conduction at the AV conduction. Vagal discharge and occulocardiac reflux decrease the heart rate and convert the tachycardia into normal sinus rhythm.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 10
Correct
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Which ion channel does not contribute to the myocardial action potential?
Your 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 11
Correct
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Why is the sub-endocardial portion of the left ventricle the most common site for ischaemic damage and myocardial infarction?
Your Answer: No blood flow occurs during systole
Explanation:The subendocardium receives the least amount of blood from the coronary arteries. 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 12
Incorrect
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 13
Correct
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Question 14
Incorrect
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 15
Correct
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The Sinoatrial node in the majority of people is supplied by the?
Your Answer: Right coronary artery
Explanation:In 60% of people, the SA node is supplied by the right coronary artery branch and in 40% of the people by the left coronary artery.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 16
Incorrect
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Pacemaker cells in the SA node and the AV node are connected by?
Your Answer: Myosin
Correct 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 17
Correct
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The term cardiac output refers to the amount of blood pumped by the heart in one minute. The rate in women is around 5 L/min, whereas in men is somewhat higher, around 5.5 L/min. Which of the equations below best describes cardiac output?
Your Answer: Stroke volume x heart rate
Explanation:Cardiac output (CO) is calculated by multiplying stroke volume (SV) by heart rate (HR): CO = HR x SV As a result, both stroke volume and heart rate are exactly proportional to cardiac output. There will be an increase in cardiac output if the stroke volume or heart rate increases, and a reduction in cardiac output if the stroke volume or heart rate lowers.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 18
Incorrect
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Where on the surface of the chest is the normal site of auscultation for the mitral area?
Your Answer: 5th intercostal space in the left lower sternal border
Correct Answer: 4th left intercostal space in the mid-clavicular line
Explanation:The mitral valve is situated in the left 4th intercostal space just beneath the sternum, in the mid clavicular line.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 19
Correct
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Vasodilatation in skeletal muscle can be caused by:
Your 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 20
Incorrect
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In Starling’s law of the heart, the decrease in tension developed by muscle contraction at high degrees of stretch is due to:
Your Answer: A relative deficiency of ATP molecules to supply all the actin and myosin cross bridges formed
Correct Answer: Disruption of myocardial fibers
Explanation:Starling law states that the force of contraction is directly proportional to the preload. When the heart muscle is stretched beyond its limit the tension that is developed decreases, this is not due to loss of formation of effective myosin and actin cross bridges. The heart muscles despite being fully stretched is never stretched to this point. The reason for this decreased tension is physical disruption of the myocardial fibers.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 21
Correct
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The ‘c’ wave in JVP corresponds more closely with……
Your 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).
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 22
Incorrect
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Activation of nitric oxide synthesis by endothelial cells is triggered by:
Your Answer: Shear stress
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 23
Incorrect
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Myocardial oxygen consumption is increased by:
Your Answer: Aortic regurgitation
Correct 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 24
Correct
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The heart rate can be accelerated by:
Your 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 25
Correct
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Which heart sounds are matched correctly?
Your Answer: All of the above
Explanation:In healthy adults, there are two normal heart sounds often described as a lub and a dub (or dup), that occur in sequence with each heartbeat. These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the atrioventricular valves and semilunar valves, respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs, adventitious sounds, and gallop rhythms S3 and S4. S3 is thought to be caused by the oscillation of blood back and forth between the walls of the ventricles initiated by blood rushing in from the atria. The reason the third heart sound does not occur until the middle third of diastole is probably that during the early part of diastole, the ventricles are not filled sufficiently to create enough tension for reverberation. S4 when audible in an adult is called a presystolic gallop or atrial gallop. This gallop is produced by the sound of blood being forced into a stiff or hypertrophic ventricle.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 26
Correct
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The amount of a substance taken up by an organ (or whole body) per unit time is equal to the arterial level minus the venous level times the blood flow.” This statement describes:
Your Answer: The Fick principle
Explanation:The essence of the Fick principle is that blood flow to an organ can be calculated using a marker substance if the following information is known:- Amount of marker substance taken up by the organ per unit time- Concentration of marker substance in arterial blood supplying the organ- Concentration of marker substance in venous blood leaving the organ
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 27
Correct
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Regarding the myofilament molecules, which of the following contains binding sites for calcium that helps to initiate contraction?
Your Answer: Troponin c
Explanation:Troponin T binds the troponin components to tropomyosin. Troponin I inhibits the interaction of myosin with actin and troponin C contains the binding sites for the Ca2+ that helps initiate contraction.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 28
Correct
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The coronary sinus, which empties into the right atrium, serves to?
Your Answer: Drain the venous supply of the myocardium
Explanation:The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). It delivers deoxygenated blood to the right atrium, as do the superior and inferior vena cava.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 29
Incorrect
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Which of the following best describes the cardiac muscle?
Your Answer: Striated and voluntary
Correct Answer: Striated and involuntary
Explanation:Cardiac muscle (heart muscle) is an involuntary, striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 30
Incorrect
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 31
Correct
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All valves are closed in which phase of the cardiac cycle?
Your Answer: Isovolumetric relaxation
Explanation:The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat, and so includes the diastole, the systole, and the intervening pause.The first stage, diastole, is when the semilunar valves (the pulmonary valve and the aortic valve) close, the atrioventricular (AV) valves (the mitral valve and the tricuspid valve) open, and the whole heart is relaxed. The second stage, atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle.The third stage, isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. The fourth stage, ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. During the fifth stage, isovolumic relaxation time, pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 32
Correct
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Question 33
Incorrect
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What is the main reason for checking the urea and electrolytes prior to commencing a patient on amiodarone?
Your Answer: To detect impaired renal function
Correct Answer: To detect hypokalaemia
Explanation:All antiarrhythmic drugs have the potential to cause arrhythmias. Coexistent hypokalaemia significantly increases this risk.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 34
Correct
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Excitation-contraction coupling in cardiac muscle involves all of the following except:
Your Answer: Binding of Ca2+ to calmodulin
Explanation:In the excitation contraction coupling model, an action potential is 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. These are voltage gates calcium channels. Calcium binds to calmodulin during contraction of the smooth muscle and not the cardiac muscles.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 35
Incorrect
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The celiac trunk consists of which arteries?
Your Answer: Left gastric, common hepatic, phrenic
Correct Answer: Left gastric, common hepatic, splenic
Explanation:The celiac trunk is the first major branch of the abdominal aorta. It is 1.25 cm in length. Branching from the aorta at thoracic vertebra 12 (T12). There are three main divisions of the celiac artery:- left gastric artery- common hepatic artery- splenic artery
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 36
Incorrect
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 37
Correct
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Factors influencing cardiac output include which of the following?
Your Answer: All of the above
Explanation:There is a correlation between resting CO and body surface area. The output per min per square meter of body surface (the cardiac index) averages 3.2l.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 38
Correct
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Question 39
Incorrect
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Regarding the surface anatomy of the orifices of the heart, where is the aortic valve located?
Your Answer: Opposite the 3rd left intercostal space bind the left margin of the sternum
Correct Answer: Opposite the left 3rd intercostal space to the left of the sternum
Explanation:The aortic valve is situated in the left 3rd intercostal space just beneath the sternum.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 40
Incorrect
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Question 41
Incorrect
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A 28-year-old patient is intubated and has a central venous catheter inserted after being diagnosed with septic shock. You keep track of her central venous pressure. The normal value for central venous pressure is which of the following?
Your Answer: 5-12 cmH 2 O
Correct Answer: 0-8 cmH 2 O
Explanation:The pressure measured in the right atrium or superior vena cava is known as central venous pressure (CVP). In a spontaneously breathing subject, the usual CVP value is 0-8 cmH2O (0-6 mmHg). At the conclusion of expiration, the CVP should be measured with the patient resting flat. The catheter’s tip should be at the intersection of the superior vena cava and the right atrium. An electronic transducer is installed and zeroed at the level of the right atrium to measure it (usually in the 4th intercostal space in the mid-axillary line). CVP is a good predictor of preload in the right ventricle. Hypovolaemia is indicated by a volume challenge of 250-500 mL crystalloid eliciting an increase in CVP that is not sustained for more than 10 minutes. CVP is influenced by a number of factors, including: Mechanical ventilation (and PEEP) Pulmonary hypertension Pulmonary embolism Heart failure Pleural effusion Decreased cardiac output Cardiac tamponade CVP is reduced by the following factors: Distributive shock Negative pressure ventilation Hypovolaemia Deep inhalation
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 42
Correct
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Question 43
Correct
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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).
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 44
Incorrect
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Which vaso metabolite decreases coronary blood flow?
Your Answer: Co2
Correct Answer: Endothelin
Explanation:Decreased O2, increased CO2, lactate, prostaglandins, adenine nucleotides, adenosine, H+, K+ and cyanide produce vasodilation and thus an increase in coronary blood flow.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 45
Correct
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 46
Correct
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What is the isolated effect of B2 stimulation on the coronaries.
Your Answer: Vasoconstriction
Explanation:Norepinephrine and epinephrine are agonists for all adrenergic receptor subtypes, although with varying affinities. Based on their physiology and pharmacology, adrenergic receptors have been divided into two principal types: alpha and betta. These types have been further differentiated into alpha-1, alpha-2, b1, and b2 receptors. Alpha-1 Receptors are located on postsynaptic cells in smooth muscle and elicit vasoconstriction. alpha-2 Receptors are localized on presynaptic membranes of postganglionic nerve terminals that synthesize norepinephrine. When activated by catecholamines, alpha-2 receptors act as negative feedback controllers, inhibiting further norepinephrine release. Activation of myocardial b1 receptors stimulates the rate and strength of cardiac contraction, and consequently increases cardiac output. b1 Receptor activation also stimulates renin release from the kidney. Another class of antihypertensive agents acts by inhibiting b1 receptors. Activation of b2 receptors by epinephrine relaxes vascular smooth muscle and results in vasodilation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 47
Incorrect
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Concerning surface anatomy, where is the base of the heart
Your Answer: 3rd 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 48
Incorrect
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What is the effect of catecholamines (i.e. increased heart rate) on the pressure volume loop?
Your Answer: Shifts the diastolic pressure curve to the right
Correct 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 49
Incorrect
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 50
Correct
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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. They are voltage gated calcium channels.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 51
Correct
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During which phase of the cardiac cycle does most of the ventricular filling occur?
Your 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 52
Incorrect
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Which of the following phases in depolarization and repolarization of cardiac muscle cells are caused by the inactivation of Na+ channels?
Your Answer: Phase 2 : plateau
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 53
Incorrect
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In which area is depolarization initiated?
Your Answer: Atria
Correct Answer: SA node
Explanation:SA node is the pacemaker of the heart. It determines the rate of contractions. It is the place where depolarization is initiated. It exhibits phase 4 depolarization or automaticity. Electrical impulses then spread to the AV node, purkinje fibers, bundle of his and the ventricular muscles.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 54
Incorrect
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Concerning surface anatomy, where is the mitral valve found?
Your Answer: Situated in the 4th intercostal space beneath the sternum
Correct Answer: Situated in the 4th intercostal space left to the sternum
Explanation:The mitral valve is situated in the left 4th intercostal space just beneath the sternum.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 55
Incorrect
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Question 56
Correct
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Question 57
Incorrect
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Coronary vasoconstriction can be caused by:
Your Answer: Hypoxia
Correct Answer: Beta blockage
Explanation:Coronary arteries contain alpha and beta receptors. The alpha receptor stimulates vasoconstriction and beta receptors stimulate vasodilation. When the chronotropic and inotropic effects of noradrenergic receptors are blocked by a B blocking drug, stimulation of the noradrenergic nerves will cause coronary vasoconstriction.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 58
Correct
-
Troponin I is inhibited by calcium binding to:
Your Answer: Troponin c
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 59
Correct
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Question 60
Incorrect
-
A 55 year old cardiac patient is comfortable at rest but heavy housework results in fatigue, palpitations or dyspnoea. What New York Heart Association class best describes the severity of their disease?
Your Answer: NYHA Class III
Correct Answer: NYHA Class II
Explanation:New York Heart Association functional classification:Class I: no limitation is experienced in any activities; there are no symptoms from ordinary activities.Class II: slight, mild limitation of activity; the patient is comfortable at rest or with mild exertion.Class III: marked limitation of any activity; the patient is comfortable only at rest.Class IV: any physical activity brings on discomfort and symptoms occur at rest.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 61
Correct
-
The bradycardia that occurs in patients with raised intracranial pressure is a result of the?
Your Answer: Cushing reflex
Explanation:When intracranial pressure is increased, the blood supply to RVLM neurons is compromised. This results in an increase in their discharge as a result of hypoxia and hypercapnia. The resultant rise in systemic arterial pressure (Cushing reflex) tends to restore the blood flow to the medulla.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 62
Incorrect
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In the blood supply of the heart, ‘dominance’ refers to the coronary artery which supplies the?
Your Answer: Sinoatrial node
Correct Answer: Posterior interventricular artery
Explanation:Dominance of the coronary artery system is defined by the artery that gives rise to the posterior interventricular artery. Dominance of the right coronary artery is more common (68%). It gives rise to the large posterior interventricular branch which goes down to the apex of the heart.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 63
Incorrect
-
Which statement about the 2nd heart sound is true?
Your Answer: It coincides with rapid ventricular filling.
Correct Answer: It is caused by closure of the aortic and pulmonary valves.
Explanation:The second heart sound is produced due to closure of the aortic and pulmonary valves. It is a high pitched dub sound. Splitting may occur due to pathology.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 64
Incorrect
-
Which is the commonest cardiovascular abnormality seen in an adult patient with Marfan’s syndrome?
Your Answer: Aortic dissection
Correct 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 65
Incorrect
-
Which of the following components regulate cardiac output?
Your Answer: A and B
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 66
Correct
-
The T-tubular system in cardiac muscle is:
Your 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 67
Incorrect
-
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 can be both shorter and longer
Correct 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 68
Correct
-
Vasodilatation of coronary arteries is caused by:
Your Answer: Hypoxia
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 69
Incorrect
-
Which of the following supplies the AV node?
Your Answer: Left anterior descending
Correct Answer: Right coronary artery
Explanation:The AV node is supplied by the right coronary artery near the origin of the posterior IV artery.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 70
Incorrect
-
Regarding cardiac contractility, catecholamines exert their inotropic effect via:
Your Answer: Β2-adrenergic receptors and gs
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 71
Incorrect
-
Which of the following suggests the presence of mitral regurgitation as well as mitral stenosis?
Your Answer: Raised JVP
Correct Answer: Displaced apex beat
Explanation:Mitral stenosis on its own does not lead to left ventricular dilatation and hence a displaced apex beat. Thus a displaced apex beat is suggestive of mixed mitral disease. The other options occur in mitral stenosis.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 72
Correct
-
Which of the following has the shortest duration:
Your Answer: Atrial systole: 0.1s
Explanation:Atrial systole: 0.1sAtrial diastole: around 0.4sVentricular diastole: 0.4-0.53s.Ventricular systole: 0.27sPR interval: 0.12-0.2 s
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 73
Incorrect
-
Describe the location of the SA node:
Your Answer: Posterior portion of the right interatrial septum
Correct 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 74
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 75
Incorrect
-
The following products of the vascular endothelium produce vasodilation except:
Your Answer: Nitrous oxide
Correct Answer: Endothelin
Explanation:Vascular endothelial growth factor (VEGF) is a signal protein produced by cells that stimulates vasculogenesis and angiogenesis. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate. VEGF’s normal function is to create new blood vessels during embryonic development, new blood vessels after injury, muscle following exercise, and new vessels (collateral circulation) to bypass blocked vessels.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 76
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 77
Correct
-
The following is true of the sinus node:
Your Answer: It generates impulses automatically & at a quicker rate than other cardiac cells
Explanation:The SA node exhibits automaticity. It generates the impulses to which the heart beats. It fires at a faster speed than the rest of the nervous components of the heart i.e. the AV nodes, purkinje fibers. This is the reason when the SA node fails the heart beats to the rhythm of the AV node.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 78
Incorrect
-
Question 79
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 80
Incorrect
-
Xanthines (for example Caffeine), exhibit their positive inotropic effect by:
Your Answer: Stimulating the sympathetic catecholamine release
Correct Answer: Inhibiting the breakdown cAMP
Explanation:Xanthines exert their positive inotropic effect by inhibiting the breakdown of the cAMP resulting in stronger and sustained contraction.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 81
Incorrect
-
Which structure forms the major part of the sternocostal surface of the heart?
Your Answer: The aortic arch
Correct Answer: Right ventricle
Explanation:The anterior (sternocostal) surface is formed mainly by the right ventricle.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 82
Correct
-
Question 83
Correct
-
Which of the following is the most common causative organism in infective endocarditis?
Your Answer: Streptococcus viridans
Explanation:Viridans Alpha-haemolytic streptococci, that are present in the mouth are the most frequently isolated microorganisms when the infection is acquired in a community setting. In contrast, Staphylococcus blood stream infections are frequently acquired in a health care setting where they can enter the blood stream through procedures that cause break in the integrity of skin like surgery, catheterisation or during access of long term indwelling catheters or secondary to intravenous injection of recreational drugs.Prosthetic valve endocarditis is commonly caused by Staphylococcus epidermidis as it is capable of growing as a biofilm on plastic surfaces
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 84
Incorrect
-
A trauma victim who has been intubated is tachycardic, hypotensive, and has a poor urine output. You feel she is dehydrated and decide to use a central venous catheter to help you manage her. As part of this, you keep an eye on the waveform of central venous pressure (CVP). Which of the following cardiac cycle phases corresponds to the CVP waveform's 'a wave'?
Your Answer: Early systole
Correct Answer: End diastole
Explanation:The pressure measured in the right atrium or superior vena cava is known as central venous pressure (CVP). In a spontaneously breathing subject, the usual CVP value is 0-8 cmH2O (0-6 mmHg). The structure of the CVP waveform is as follows: The CVP’s components are listed in the table below: Component of the waveform The cardiac cycle phase. mechanical event mechanical event Diastole Atrial contraction a wave C wave v wave Early systole The tricuspid valve closes and bulges Late Systole Filling of the atrium with systolic blood x descent y descent Mid systole Relaxation of the atrium Early diastole Filling of the ventricles at an early stage
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 85
Incorrect
-
In a normal heart rate at rest, the left ventricular end-diastolic volume is ….
Your Answer: 70-100 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).
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 86
Incorrect
-
In the cardiac cycle, all of the following are true except:
Your Answer: The ejection fraction is about 55%
Correct Answer: Mitral valve is closed by contraction of papillary muscles
Explanation:The mitral valve closes during the phase of isovolumetric contraction. After atrial systole blood is pumped into the ventricles. When the ventricles begin to contract the pressure in the ventricles increases enough to close the mitral valve but not to open the aortic and pulmonary valves. During this phase the volume remains constant but the pressure continues to increase.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 87
Incorrect
-
Which of the following makes up the thick filaments?
Your Answer: Actin
Correct Answer: Myosin
Explanation:The thick filaments are made up of myosin and the thin filaments are made up of actin. The thick filaments are twice the size of the thin filaments and are aligned to form the A band. The thin filaments extending out from the A band form the less dense I bands.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 88
Incorrect
-
According to Poiseuille’s formula, which 1 of the following will lead to increased flow?
Your Answer: Smaller radius
Correct Answer: Shorter tube
Explanation:V = π p r4 / 8 η lwhere V = discharge volume flow (m3/s)p = pressure difference between the ends of the pipe (N/m2, Pa)r = internal radius of pipe (m)l = length of pipe (m)η = viscosity of fluid
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 89
Incorrect
-
Which of the following conditions has no effect on cardiac output?
Your Answer: Anxiety
Correct Answer: Sleep
Explanation:Sleep has no effect on the cardiac output. Anxiety, excitement and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 90
Incorrect
-
The rate of depolarisation of the sinus node membrane potential is modulated by all the following except:
Your Answer: Autonomic tone
Correct Answer: Cardiac output
Explanation:Cardiac output has no effect on the depolarization of the pacemaker potential of the heart.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 91
Incorrect
-
Which one of the following ECG findings is least associated with digoxin use?
Your Answer: Flattened T waves
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 92
Incorrect
-
Which of the following normally has a slow depolarizing “prepotential”?
Your Answer: Bundle of his
Correct Answer: Sinoatrial node
Explanation:There are 2 main types of action potentials (AP) in the heart, the slow response and the fast response:The slow response is initiated by the slow calcium-sodium channels, found in the SA node (which is the natural pacemaker of the heart) and the conduction fibers of the AV node.The fast response occurs in the atrial and ventricles muscle cells and the purkinje fibers.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 93
Correct
-
When does the heart rate decrease?
Your Answer: Pressure on the eyeball
Explanation:Various vagotonic manoeuvres (e.g. Valsalva manoeuvre, carotid sinus massage, pressure on eyeballs, ice-water facial immersion, swallowing of ice-cold water) result in increased parasympathetic tone through the vagus nerve which results in a decrease in heart rate. These manoeuvres may be clinically useful in terminating supraventricular arrhythmias.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 94
Incorrect
-
Concerning coronary arteries, what is the net effect of B2 stimulation on the heart (e.g. Running athlete)?
Your Answer: Vasodilation directly
Correct Answer: Vasodilation via production of metabolites
Explanation:The coronary arterioles contain α-adrenergic receptors, which cause vasoconstriction, and β-adrenergic receptors, which cause vasodilation. Activity in the noradrenergic nerves to the heart and injections of norepinephrine cause coronary vasodilation. However, norepinephrine also increases the heart rate and the force of cardiac contraction, and the vasodilation is due to production of vasodilator metabolites in the myocardium secondary to the increase in its activity. As exercise has the same effect as sympathetic stimulation, it will result in vasodilation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 95
Correct
-
Xanthines such as caffeine and theophylline are positively inotropic due to:
Your Answer: Inhibition of cAMP breakdown
Explanation:Xanthines exert their positive inotropic effect by inhibiting the breakdown of the cAMP resulting in stronger and sustained contractions.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 96
Correct
-
The initial rapid depolarization in the action potential of cardiac muscle cells is due to:
Your Answer: Opening of voltage-gated Na+ channels
Explanation:The initial depolarization of the action potential in a cardiac muscle cell is due to the sodium current generated by opening of the voltage gated sodium channels leading to an influx of sodium ions into the cell and raising the membrane potential towards threshold.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 97
Correct
-
Tunica intima is made up of?
Your Answer: Endothelial cells
Explanation:Tunica intima is a single cell thick lining of endothelial cells that lines the inside of the blood vessels. It is the inner most layer of the blood vessel.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 98
Correct
-
AV valves open during?
Your 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 99
Correct
-
What is the normal duration of the ST segment?
Your Answer: 0.08 s
Explanation:The ST segment lies between the QRS complex and the T-wave. The normal duration of the ST segment is 0.08 s. ST-segment elevation or depression may indicate myocardial ischaemia or infarction.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 100
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 101
Correct
-
Question 102
Incorrect
-
The process by which depolarization of the muscle fiber initiates contraction is called?
Your Answer: Activation of contraction
Correct Answer: Action potential
Explanation:This process is known as an action potential. Upon generation of an action potential when depolarization reaches threshold, it spreads throughout the muscle fiber, resulting in generation of an excitation-contraction coupling leading to contraction of the muscle.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 103
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 104
Correct
-
The function of ATP in cardiac muscle contraction includes:
Your Answer: Binding to myosin after the power stroke to allow uncoupling of actin and myosin
Explanation:After calcium binds to the troponin C, there is a conformational change in the structure of troponin I and tropomyosin, which moves out of the way and frees the site where myosin can bind to actin. This results in the formation of the cross linkage of the actin and myosin giving rise to the power stroke in the contraction phase. This occurs with the release of ADP. When ATP combines to this complex it breaks and the cycle repeats itself.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 105
Incorrect
-
The Wiebel-Palade body found in the endothelial cells is responsible for the production and release of which factor?
Your Answer: Tissue plasminogen activator
Correct Answer: Von Willebrand factor
Explanation:Weibel-Palade bodies are the storage granules of endothelial cells, the cells that form the inner lining of the blood vessels and heart. They store and release two principal molecules, von Willebrand factor and P-selectin, and thus play a dual role in haemostasis and inflammation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 106
Incorrect
-
Calcium needed for cardiac muscle contraction is made available during which phase of the action potential?
Your Answer: 3
Correct 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 107
Incorrect
-
Where is the carotid sinus located?
Your Answer: At the start of the carotid artery
Correct Answer: After the bifurcation of the carotid artery, on the internal carotid
Explanation:The carotid sinus is a small dilation in the internal carotid artery just above its bifurcation into the external and internal carotid branch. Baroreceptors are present at this dilation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 108
Correct
-
Angina pectoris develops when the flow through the coronary artery becomes:
Your Answer: Oxygen deficient
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 109
Correct
-
Question 110
Incorrect
-
Select the correct statement regarding the 4th heart sound, it?
Your Answer: Occurs during isovolumetric ventricular contraction.
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 111
Incorrect
-
The branche(s) of the left coronary artery are
Your Answer: Posterior descending artery: no comes from right coronary artery
Correct Answer: A and b
Explanation:Posterior descending artery comes from Right coronary artery. The anterior interventricular artery is otherwise known as the anterior descending branch.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 112
Correct
-
Which of the following is NOT true of the parasympathetic control of the heart?
Your 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 113
Correct
-
Question 114
Correct
-
Question 115
Correct
-
Question 116
Correct
-
Question 117
Correct
-
What type of intercellular connection found between cardiac muscle fibers allow for the spread of excitation from one cell to another?
Your Answer: Gap junctions
Explanation:The cardiac muscles have gap junctions in-between the cells. They form 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 118
Incorrect
-
Regarding cardiac muscle contractility, the afterload refers to:
Your Answer: The amount of blood pumped out of the heart per beat
Correct Answer: The resistance against which blood is expected
Explanation:The afterload for the left ventricle is the aortic pressure. Hence it is this pressure that offers resistance against which the blood is to be expelled from the heart.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 119
Incorrect
-
You've been requested to give a discussion to a group of medical students about cardiovascular physiology. One of them inquires about cardiac output and asks if you can explain it. Which of the following statements is correct?
Your Answer: An average resting cardiac output in a man is 6 L/min
Correct Answer: An average resting cardiac output in a woman is 5 L/min
Explanation:The terminology cardiac output refers to the amount of blood pumped by the heart in one minute. Women’s rates are around 5 L/min, whereas men’s rates are somewhat higher, around 5.5 L/min. Cardiac output (CO) is calculated by multiplying stroke volume (SV) by heart rate (HR): CO = HR x SV As a result, both stroke volume and heart rate are exactly proportional to cardiac output. There will be an increase in cardiac output if the stroke volume or heart rate increases, and a reduction in cardiac output if the stroke volume or heart rate lowers.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
-
Question 120
Incorrect
-
B1 adrenergic stimulation produces:
Your Answer: Decrease in muscle contraction
Correct Answer: Increase in calcium cytosolic concentration
Explanation:Norepinephrine secreted by the sympathetic endings binds to B1 receptors, and the resulting increase in intracellular cAMP facilitates the opening of L channels, increasing Ica and the rapidity of the depolarization phase of the impulse and activates PKA which leads to phosphorylation of the voltage-gated Ca2+ channels, causing them to spend more time in the open state.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 121
Incorrect
-
Currents caused by opening of which of the following channels contribute to the repolarization phase of the action potential of the ventricular muscle fibers?
Your Answer: Sodium channels
Correct Answer: Potassium channels
Explanation:Depolarization occurs due to opening of the voltage gated sodium channels. Repolarization occurs due to opening of the voltage gates potassium channels causing an out flux of potassium ions, decreasing the membrane potential towards resting potential.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 122
Incorrect
-
The a-wave is created by:
Your Answer: Increased pulmonary vascular pressure
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 123
Incorrect
-
Which of the following is a method for measurement of cardiac output?
Your Answer: Starling method
Correct Answer: Indicator dilution method
Explanation:There are two methods of calculating the cardiac output in humans other than doppler with echocardiography: The direct Fick’s method and the indicator dilution method. In the indicator dilution technique, a known amount of a substance such as a dye or, more commonly, a radioactive isotope is injected into an arm vein and the concentration of the indicator in serial samples of arterial blood is determined. The output of the heart is equal to the amount of indicator injected divided by its average concentration in arterial blood after a single circulation through the heart.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 124
Correct
-
Cholinergic vagal supply to the SA and AV nodes results in slowing of the heart rate via:
Your Answer: M2 muscarinic receptors
Explanation:M2 muscarinic receptors are the receptors for the parasympathetic system to the SA and the AV node.
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This question is part of the following fields:
- Cardiovascular
- Physiology
-
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Question 125
Correct
-
During exercise, a man consumes 2L O2/min, his arterial 02 content is 190 ml/l and the 02 content of his mixed venous blood is 130ml/l. His cardiac output is approximately:
Your Answer: 33l/min
Explanation:In Fick’s original method, the following variables are measured:VO2, oxygen consumption in ml of pure gaseous oxygen per minute. This may be measured using a spirometer within a closed rebreathing circuit incorporating a CO2 absorberCa, the oxygen concentration of blood taken from the pulmonary vein (representing oxygenated blood)Cv, the oxygen concentration of blood from an intravenous cannula (representing deoxygenated blood)From these values, we know that:VO2 = (CO x Ca) – (CO x Cv)where CO = Cardiac Output, Ca = Oxygen concentration of arterial blood and Cv = Oxygen concentration of mixed venous blood.This allows us to sayCO = VO2/{Ca – Cv}and hence calculate cardiac output.Therefore CO = 2/(0.190-0.130) = 33l/minNote that (Ca – Cv) is also known as the arteriovenous oxygen difference.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 126
Correct
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Cross-bridges between actin and myosin filaments contain:
Your Answer: Calcium ions
Explanation:At rest troponin I is bound to actin and tropomyosin and covers the site where the myosin head interacts with actin. When calcium enters into the muscle, it binds with troponin C and causes a structural change in troponin I which moves out of the myosin binding site and causes the cross bridges between the actin and myosin filaments to occur.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 127
Correct
-
The interventricular septum is supplied anteriorly by the?
Your Answer: Left anterior descending artery
Explanation:The anterior interventricular artery or left anterior descending artery supplies the anterior 2/3rds of the interventricular septum.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 128
Incorrect
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 129
Incorrect
-
Closure of the tricuspid valve is marked by which of the following features of the jugular venous waveform?
Your Answer: a wave
Correct Answer: c wave
Explanation:The jugular venous pressure (JVP) classically has three upward deflections and two downward deflections. 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).
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 130
Incorrect
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The approximate incidence of deep venous thrombosis (DVT) in the general population each year is:
Your Answer: 50 per 1000
Correct Answer: 1 per 1000
Explanation:About 1 in 1000 adults per year has DVT, but as of 2011, available data is dominated by North American and European populations. DVT is rare in children, with an incidence of about 1 in 100,000 a year. From childhood to old age, incidence increases by a factor of about 1000, with almost 1% of the elderly experiencing DVTs yearly.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 131
Incorrect
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The function of Troponin T in cardiac muscle is?
Your Answer: Generation of ATP which is passed on to the contractile mechanism
Correct Answer: Allows attachment of troponin components to tropomyosin
Explanation:Troponin T binds the troponin components to tropomyosin. Troponin I inhibits the interaction of myosin with actin, and troponin C contains the binding sites for the Ca2+ that helps initiate contraction.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 132
Incorrect
-
Sinus bradycardia may be caused by disease of which of the following:
Your Answer: Left coronary artery
Correct Answer: Right coronary artery
Explanation:Disease of the right coronary artery may cause sinus bradycardia and AV nodal block.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 133
Incorrect
-
Water hammer pulse is found in:
Your Answer: Aortic stenosis
Correct Answer: Aortic insufficiency
Explanation:Watson’s water hammer pulse is the medical sign which describes a pulse that is bounding and forceful, rapidly increasing and subsequently collapsing, as if it were the sound of a water hammer that was causing the pulse. A water hammer was a Victorian toy in which a tube was half filled with fluid, the remainder being a vacuum. The child would invert and reinvert the tube; each time the impact of the fluid at each end would sound like a hammer blow. This is associated with increased stroke volume of the left ventricle and decrease in the peripheral resistance leading to the widened pulse pressure of aortic regurgitation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 134
Incorrect
-
Which of the following concerning PR interval is INCORRECT?
Your Answer: PR interval allows the atria to contract and fill the ventricle with blood
Correct Answer: Always measured from the beginning of p wave to the beginning of r wave
Explanation:The PR interval measures the time from the start of atrial depolarization to the start of ventricular depolarization. The PR interval is only measured from the beginning of P wave to beginning of R wave if the Q wave is absent.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 135
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 136
Incorrect
-
Concerning S3, which of the following statements is INCORRECT?
Your Answer: Occurs during ventricular rapid filling phase
Correct Answer: Coincide with atrial contraction
Explanation:A third heart sound also called a ventricular gallop occurs at the beginning of diastole after S2 and is lower in pitch than S1 or S2 as it is not of valvular origin. The third heart sound is benign in youth, some trained athletes, and sometimes in pregnancy but if it re-emerges later in life it may signal cardiac problems, such as a failing left ventricle as in dilated congestive heart failure (CHF). S3 is thought to be caused by the oscillation of blood back and forth between the walls of the ventricles initiated by blood rushing in from the atria. The reason the third heart sound does not occur until the middle third of diastole is probably that during the early part of diastole, the ventricles are not filled sufficiently to create enough tension for reverberation. It may also be a result of tensing of the chordae tendineae during rapid filling and expansion of the ventricle. In other words, an S3 heart sound indicates increased volume of blood within the ventricle. An S3 heart sound is best heard with the bell-side of the stethoscope (used for lower frequency sounds). A left-sided S3 is best heard in the left lateral decubitus position and at the apex of the heart, which is normally located in the 5th left intercostal space at the midclavicular line. A right-sided S3 is best heard at the lower-left sternal border. The way to distinguish between a left and right-sided S3 is to observe whether it increases in intensity with inhalation or exhalation. A right-sided S3 will increase on inhalation, while a left-sided S3 will increase on exhalation.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 137
Incorrect
-
Which one of the following is a risk factor for torsade de pointes?
Your Answer: Hyperkalaemia
Correct Answer: Hypothermia
Explanation:The following is a list of factors associated with an increased tendency toward torsades de pointes:- Hypokalaemia (low blood potassium)- Hypomagnesemia (low blood magnesium)- Hypocalcaemia (low blood calcium)- Bradycardia (slow heartbeat)- Heart failure- Left ventricular hypertrophy- Hypothermia- Subarachnoid haemorrhage- Hypothyroidism
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 138
Incorrect
-
The positive inotropic effect of digoxin is due to?
Your Answer: Inhibition of breakdown of cAMP
Correct Answer: Inhibition of the sodium potassium ATPase in the myocardium
Explanation:Digitalis compounds are potent inhibitors of cellular Na+/K+-ATPase. This ion transport system moves sodium ions out of the cell and brings potassium ions into the cell. By inhibiting the Na+/K+-ATPase, cardiac glycosides cause the intracellular sodium concentration to increase. This then leads to an accumulation of intracellular calcium via the Na+/Ca++ exchange system. In the heart, increased intracellular calcium causes more calcium to be released by the sarcoplasmic reticulum, thereby making more calcium available to bind to troponin-C, which increases contractility (inotropy).
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 139
Correct
-
Myocyte action potentials – Choose the false statement:
Your Answer: Repolarisation is due to net k+ influx
Explanation:Final repolarization (phase 3) to the resting membrane potential (phase 4) is due to closure of the Ca2+ channels and a slow, delayed increase of K+ efflux through various types of K+ channels.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 140
Incorrect
-
Which of the following structures is not part of the conducting system of the heart?
Your Answer: Internodal pathway
Correct 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
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 141
Incorrect
-
When looking at the JVP what does the c wave signify:
Your Answer: Ventricular diastole
Correct Answer: Isovolumetric ventricular contraction
Explanation:The C wave signifies a rise in the atrial pressure during isovolumetric contraction due to the tricuspid valve bulging into the atria.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 142
Incorrect
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The postextrasystolic potentiation of myocardial contractility is due to:
Your Answer: Increased ventricular filling
Correct Answer: Increase in intracellular Ca2+
Explanation:The postextrasystolic potentiation of myocardial contractility Is not due to ventricular filling. It occurs in isolated locations in the heart and is due to increase availability of intracellular calcium.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 143
Incorrect
-
Regarding cardiac output, an increased ejection fraction results from increases in which of the following?
Your Answer: None of the above
Correct Answer: Strength of contraction without increase in muscle fiber length
Explanation:When the strength of contraction increases without an increase in fiber length, the EF increases.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 144
Incorrect
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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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 145
Incorrect
-
Myocardium requires more oxygen to expel blood in:
Your Answer: A stenotic pulmonary valve
Correct Answer: A stenotic aortic valve
Explanation:In aortic valve stenosis, increased ventricular pressure Is needed to expel the blood into the aorta. Increased pressure means increased contractility hence increase O2 consumption by the heart muscles.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 146
Incorrect
-
Activation of baroreceptor reflex involves:
Your Answer: Increase in heart rate base of inhibition of the vagal cardiac motor neurons
Correct 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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 147
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]
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 148
Incorrect
-
The most resistant area in the brain to hypoxia is:
Your Answer: Inferior colliculus
Correct Answer: Brain stem
Explanation:The structures in the brainstem are more resistant to hypoxia than the cerebral cortex and the rest of the brain structures.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 149
Incorrect
-
Which one of the following have not been shown to improve mortality in patients with chronic heart failure?
Your Answer: Beta-blockers
Correct Answer: Furosemide
Explanation:A number of drugs have been shown to improve mortality in patients with chronic heart failure:• ACE inhibitors (SAVE, SOLVD, CONSENSUS)• spironolactone (RALES)• beta-blockers (CIBIS)• hydralazine with nitrates (VHEFT-1)
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 150
Incorrect
-
The basic unit of contraction in myocytes is:
Your Answer: Myosin
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.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
