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Question 1
Incorrect
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The triangle with the heart at its centre, using limb leads is called:
Your Answer: Duke
Correct Answer: Einthoven
Explanation:The Einthoven triangle is formed by placing the limb leads on both the arms and on the left leg with the heart in the centre.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 2
Incorrect
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The hyperpolarization phase of pacemaker cells is dominated by ____ current.
Your Answer: Ca++
Correct Answer: K+
Explanation:The hyperpolarization phase is a continuation of the repolarization phase but the membrane potential dips below the resting membrane potential. This results due to the fact that the K+ channels take a longer time to close than the Na+ channels. Hence efflux of the K+ will result in hyperpolarization.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 3
Incorrect
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Which of the atrial pressure changes represents the a-wave of the JVP
Your Answer: Rise in atrial pressure before tricuspid valve opens
Correct Answer: 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
- Medicine
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Question 4
Correct
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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: 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
- Medicine
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Question 5
Incorrect
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The T-tubular system in cardiac muscle is:
Your Answer: Has serca molecules that pump Ca2+ into the SR to initiate muscle relaxation
Correct Answer: Transmits action potential from sarcolemma to the SR to allow for Ca2+ release into the cytoplasm
Explanation:Action potentials are transmitted to the fibrils of a fiber through the T tubule system. It triggers the release of Ca 2+ from the terminal cisterns. Depolarization of the T tubules activates the sarcoplasmic reticulum through the dihydropyridine receptors, which are voltage gated calcium channels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 6
Correct
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Question 7
Incorrect
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B1 adrenergic stimulation produces:
Your Answer: Negative inotropy
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
- Medicine
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Question 8
Incorrect
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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
- Medicine
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Question 9
Incorrect
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Cholinergic vagal supply to the SA and AV nodes results in slowing of the heart rate via:
Your Answer: B1 receptors
Correct Answer: M2 muscarinic receptors
Explanation:M2 muscarinic receptors are the receptors for the parasympathetic system to the SA and the AV node.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 10
Correct
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The following is true in relation to coronary venous drainage?
Your Answer: Most venous return ultimately drains into right atrium via the coronary sinus
Explanation:Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 11
Incorrect
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Endothelial cells are attached to adjacent cells by adherent junctions via:
Your Answer: Integrins
Correct Answer: Cadherins
Explanation:Cadherins are calcium dependant molecules that mediate cell to cell adhesions in epithelial and endothelial cells among others.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 12
Correct
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Which of the following is NOT an effect of a positive inotropic agent on the heart?
Your Answer: It decreases the rate of rise in ventricular blood pressure during systole
Explanation:Inotropic agents increase the contractility of the heart as well as the rate of rise in ventricular blood pressure during systole, generating a greater pressure and increasing the stroke volume e.g. like catecholamines do.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 13
Incorrect
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All of the following are consistent with the indicator dilution method except---
Your Answer: When saline is used as an indicator, it is easy to make repeated determinations
Correct Answer: In thermodilution, the indicator used is warm saline
Explanation:In thermodilution, the indicator used is cold saline.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 14
Correct
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Which factor produced by the endothelium is responsible for the regulation of vascular cell growth?
Your Answer: Vascular endothelial growth factor (VEGF)
Explanation:VEGF is produced by the endothelial cells and is the major growth factor responsible for causing vasculogenesis. Some isoforms of this growth factor also have a prominent role in formation of lymphatic vessels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 15
Correct
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Question 16
Correct
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What is the most common cardiac defect seen in patients with Down’s syndrome?
Your Answer: Atrioventricular septal defect
Explanation:The rate of congenital heart disease in new-borns with Down syndrome is around 40%. Of those with heart disease, about 80% have an atrioventricular septal defect or ventricular septal defect with the former being more common. Mitral valve problems become common as people age, even in those without heart problems at birth.[3] Other problems that may occur include tetralogy of Fallot and patent ductus arteriosus.[38] People with Down syndrome have a lower risk of hardening of the arteries
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 17
Incorrect
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The SA and AV nodes are usually supplied by which artery?
Your Answer: Left anterior descending artery
Correct Answer: Right coronary artery
Explanation:The right coronary artery supplies the right atrium, right ventricle, SA and AV nodes.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 18
Incorrect
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In ventricular fibrillation (VF), the first defibrillation attempt (with a biphasic defibrillator) should be made at:
Your Answer: 100 J
Correct Answer: 200 J
Explanation:Defibrillation is a common treatment for life-threatening cardiac dysrhythmias and ventricular fibrillation. If the patient is in Ventricular tachycardia (VT) or ventricular fibrillation (VF) on the monitor, immediately apply the pads and shock the patient with 120-200 Joules on a biphasic defibrillator or 360 Joules on a monophasic defibrillator.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 19
Correct
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Which of the following concerning PR interval is INCORRECT?
Your 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
- Medicine
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Question 20
Correct
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The positive inotropic effect of digoxin is due to?
Your 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
- Medicine
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Question 21
Incorrect
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In a 30 year old male with hypertrophic obstructive cardiomyopathy (HOCM), which of the following is not associated with increased risk of sudden death?
Your Answer: left ventricular hypertrophy (LVH)
Correct Answer: Age
Explanation:Hypertrophic cardiomyopathy (HCM) is a disease in which a portion of the myocardium (heart muscle) is enlarged without any obvious cause, creating functional impairment of the heart. It is the leading cause of sudden death in young athletes. The major risk factors for sudden death (SD) are recent unexplained syncope unlikely to be neurocardiogenic; HCM-related SD in first-degree or other close relatives; repetitive and/or prolonged nonsustained ventricular tachycardia (NSVT) episodes on Holter or extended ambulatory monitoring; massive left ventricular hypertrophy (LVH) (wall thickness ≥30 mm); extensive/diffuse late gadolinium enhancement (LGE); end-stage heart failure usually with systolic dysfunction; and thin-walled akinetic LV apical aneurysm with regional scarring.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 22
Correct
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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
- Medicine
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Question 23
Correct
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Which coronary artery supplies the right atria?
Your Answer: Right coronary
Explanation:The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum. The circumflex artery arises from the left coronary artery and follows the coronary sulcus to the left. Eventually, it will fuse with the small branches of the right coronary artery. The right coronary artery proceeds along the coronary sulcus and distributes blood to the right atrium, portions of both ventricles, and the heart conduction system.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 24
Correct
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Question 25
Incorrect
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The internodal tract of Bachman:
Your Answer: Connects the AV node to the rest of the heart
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
- Medicine
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Question 26
Correct
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Which of the following conditions has no effect on cardiac output?
Your Answer: Sleep
Explanation:Sleep has no effect on the cardiac output. Anxiety, excitement and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 27
Incorrect
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Which of the following intercellular connections is important in endothelial barrier function?
Your Answer: Desmosomes
Correct Answer: Tight junctions
Explanation:Tight junctions surround the apical margins of the epithelial cells such as in the intestinal mucosa and the choroid plexus. They are also important to the endothelial barrier function. They are made up of ridges that adhere to each other strongly at the cell junction, obliterating the space completely between the cells.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 28
Correct
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Which of the following pairs are correct concerning arteriolar tone?
Your Answer: Hormonal control: catecholamines affect the adrenergic receptors of the vascular smooth muscle
Explanation:Catecholamines released from the adrenal medulla act on the noradrenergic receptors of the vascular smooth muscles. In the skeletal muscles and liver it causes vasodilation whilst it causes vasoconstriction in the rest of the blood vessels of the body.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 29
Correct
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Question 30
Correct
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Most of the venous blood returns to the heart through the:
Your Answer: Coronary sinus and anterior cardiac veins
Explanation:Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins which drain into the right atrium.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 31
Incorrect
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Question 32
Incorrect
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Which membrane bound protein in the sarcoplasmic reticulum regulates calcium return from the cytosol to the sarcoplasmic reticulum?
Your Answer: Actin
Correct Answer: Phospholamban
Explanation:Phosphorylation of phospholamban increases calcium ATPase activity and sequestration of calcium in the sarcoplasmic reticulum. An increased rate of relaxation is explained because cAMP also activates the protein phospholamban, situated on the membrane of the sarcoplasmic reticulum (SR), that controls the rate of uptake of calcium into the SR. The latter effect explains enhanced relaxation (lusitropic effect).
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 33
Incorrect
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The function of Troponin T in cardiac muscle is?
Your Answer: Binding site for Ca2+ to initiate muscle contraction
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
- Medicine
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Question 34
Incorrect
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Coronary vasoconstriction can be caused by:
Your Answer: Vagal tone
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
- Medicine
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Question 35
Correct
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Activation of nitric oxide synthesis by endothelial cells is triggered by:
Your 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
- Medicine
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Question 36
Incorrect
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Coronary flow is reduced during
Your Answer: Ventricular filling
Correct Answer: Tachycardia
Explanation:Maximum amount of blood flow in the coronary arteries occur during diastole. When the heart rate increases which is also called tachycardia the duration of diastole decreases. Hence the amount of blood flow to the cardiac muscle also decreases.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 37
Incorrect
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Vasodilatation in skeletal muscle can be caused by:
Your Answer: Thromboxane a2
Correct Answer: Sympathetic cholinergic nerves
Explanation:In skeletal muscles some fibers that cause vasodilation run with the nerves of the sympathetic system but are cholinergic in nature. These nerves are not active during rest but become active during exercise and stress.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 38
Correct
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Concerning surface anatomy, where is the aortic valve found?
Your Answer: Situated in the left third intercostal space underneath the sternum
Explanation:The aortic valve is situated in the left 3rd intercostal space just beneath the sternum.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 39
Incorrect
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The effects of β1 stimulation include the following
Your Answer: Increased Ca++ efflux from myocytes
Correct Answer: Increased strength of contraction
Explanation:β1 stimulation include the phosphorylation of L type Ca++ channels and phospholamban and increased Ca++ influx from myocytes.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 40
Correct
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Question 41
Incorrect
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Which of the following are responsible for the 4th heart sound?
Your Answer: Elevated diastolic pressure in the aortic and pulmonary artery
Correct Answer: Ventricular hypertrophy
Explanation:The fourth heart sound is not normally audible in a normal adult. It occurs as a consequence of ventricular hypertrophy. It is caused by filling of the ventricle in atrial systole.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 42
Correct
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The posterior aspect of the interventricular septum is supplied by:
Your Answer: A branch of the right coronary artery
Explanation:The posterior aspect of the heart is supplied by the posterior interventricular artery which is a branch of the right coronary artery.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 43
Correct
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The amount of a substance taken up by an organ (or whole body) per unit time is = (the arterial level - the venous level) * the blood flow. This statement describes?
Your Answer: The Fick principle
Explanation:The essence of the Fick principle is that blood flow to an organ can be calculated using a marker substance if the following information is known:- Amount of marker substance taken up by the organ per unit time- Concentration of marker substance in arterial blood supplying the organ- Concentration of marker substance in venous blood leaving the organ
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 44
Incorrect
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If both the noradrenergic and the cholinergic systems are blocked in the heart, the rate will be approximately:
Your Answer: 50/ min
Correct Answer: 100/min
Explanation:The normal heart beat is about 70/min. This is due to a predominant parasympathetic activity. If sympathetic activity was unopposed the heart rate would have been 150/min. When both the noradrenergic and cholinergic systems are blocked the heart rate is 100/min. This is the normal firing rate of the SA node.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 45
Incorrect
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Which ion channel does not contribute to the myocardial action potential?
Your Answer: Transient outward potassium channel
Correct Answer: Chloride channel
Explanation:The upstroke in the cardiac action potential is due to opening of the sodium channels and an influx of sodium into the cell. The initial repolarization phase is due to transient opening of the potassium channels along with calcium channels. Influx of calcium causes the prolonged plateau phase of the action potential. Delayed opening of the rectifier potassium channel and delayed closure of the calcium channel leads to the repolarization phase of cardiac action potential.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 46
Incorrect
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In which area is depolarization initiated?
Your Answer: Purkinje fibers
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
- Medicine
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Question 47
Incorrect
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Dicrotic notch is produced by which valves?
Your Answer: 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
- Medicine
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Question 48
Correct
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Question 49
Incorrect
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Which of the following normally has a slow depolarizing “prepotential”?
Your Answer: Purkinje fibers
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
- Medicine
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Question 50
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
- Medicine
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Question 51
Incorrect
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Which of the following occurs during a Valsalva manoeuvre?
Your Answer: Disruption of autonomic function
Correct Answer: An initial rise in blood pressure
Explanation:The Valsalva maneuver involves forced expiration against a closed glottis. It has several phases, each affecting the cardiovascular system differently:
- Phase I: During the initial forced expiration against the closed glottis, there is a transient rise in intrathoracic pressure, which compresses the thoracic aorta and causes a brief increase in blood pressure.
- Phase II: Continued straining leads to decreased venous return to the heart, reducing cardiac output and causing a drop in blood pressure. This phase is characterized by a compensatory increase in heart rate.
- Phase III: Upon releasing the strain, there is a sudden drop in intrathoracic pressure, which momentarily decreases blood pressure.
- Phase IV: Blood pressure then rises rapidly as venous return to the heart is restored, leading to increased cardiac output. This is often followed by a reflex bradycardia (slow heart rate).
Given these phases, the most accurate statement about what occurs during the Valsalva maneuver is the initial rise in blood pressure (Phase I).
Other options explained:
- Forced inspiration against a closed glottis: Incorrect. The Valsalva maneuver involves forced expiration, not inspiration, against a closed glottis.
- Low intrathoracic pressures throughout: Incorrect. The Valsalva maneuver involves high intrathoracic pressures due to forced expiration.
- Disruption of autonomic function: Incorrect. The Valsalva maneuver affects autonomic function but does not disrupt it. Instead, it triggers autonomic responses to changes in blood pressure and heart rate.
- No change: Incorrect. The Valsalva maneuver causes significant changes in blood pressure and heart rate.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 52
Incorrect
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The celiac trunk consists of which arteries?
Your Answer: Right gastric, common hepatic, superior mesenteric
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
- Medicine
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Question 53
Incorrect
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Which of the following corresponds to an oblique line drawn from the sternal end of the left 3rd costal cartilage to the sternal end of the right 6th costal cartilage?
Your Answer: Pulmonary trunk
Correct Answer: Atrio-ventricular (coronary) groove
Explanation:The AV groove corresponds to the right border of the heart. The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 54
Correct
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What is a characteristic findings on ECG in hyperkalaemia?
Your Answer: Tall, tented T waves
Explanation:Hyperkalaemia leads to:
– Prolonged PR interval
– Small P waves
– Tall, tented T waves
– Widened QRS complexes and eventually asystole.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 55
Correct
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Which of the following results in the resting membrane potential of a myocyte?
Your Answer: Activation of outward K+ channels
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
- Medicine
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Question 56
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
- Medicine
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Question 57
Incorrect
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Which of the following is first to rise following myocardial infarction?
Your Answer: Troponin I
Correct 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
- Medicine
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Question 58
Incorrect
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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
- Medicine
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Question 59
Incorrect
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Which of the following does not lower ventricular rate in atrial fibrillation?
Your Answer: Acetylcholine
Correct 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
- Medicine
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Question 60
Incorrect
-
Which is the commonest cardiovascular abnormality seen in an adult patient with Marfan’s syndrome?
Your Answer: Mitral regurgitation
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
- Medicine
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Question 61
Incorrect
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Calcium is mobilized from the sarcoplasmic reticulum through:
Your Answer: Passive diffusion
Correct Answer: Ryanodine receptor (RyR2) calcium release channels
Explanation: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. As a result intracellular calcium increases binding to troponin C resulting in contraction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 62
Correct
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Myocardial contractility is improved by:
Your Answer: Caffeine
Explanation:Caffeine and other theophyllines breakdown cAMP and have a positive ionotropic effect on the heart. Drugs like quinidine, procainamide and conditions like hypoxia and hypercapnia decreases the contractility of the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 63
Incorrect
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During which phase of the cardiac cycle does most of the ventricular filling occur?
Your Answer: Isovolumetric ventricular contraction
Correct Answer: Ventricular diastole
Explanation:During the phase of ventricular diastole when the heart muscle relaxes and all the valves are open, blood flows easily into the heart. This is the phase of rapid ventricular filling. During isovolumetric contraction and relaxation the volume of blood in the heart does not change. During ventricular ejection blood enters into the aorta and pulmonary vessels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 64
Correct
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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
- Medicine
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Question 65
Incorrect
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Question 66
Correct
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Question 67
Incorrect
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Closure of the tricuspid valve is marked by which of the following features of the jugular venous waveform?
Your Answer: v 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
- Medicine
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Question 68
Correct
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Vasodilatation of coronary arteries is caused by:
Your Answer: Hypoxia
Explanation:The heart is highly metabolically active and boasts the highest oxygen consumption by mass of any organ. This demand for oxygen is met by the coronary circulation, which is responsible for delivering blood to the myocardium and represents approximately 5% of cardiac output. Vasodilation may be due to the local effect of hypoxia on coronary vessels, or local metabolic vasodilation, or the activation of β-adrenoceptors or some combination of these mechanisms.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 69
Incorrect
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Generalized vasoconstrictors include:
Your Answer: Nitric oxide, carbon monoxide, natriuretic peptide
Correct Answer: Norepinephrine, endothelin, angiotensin ii
Explanation:Vasopressin, angiotensin II, adrenaline and endothelin are generalized vasoconstrictors.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 70
Correct
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Regarding cardiac muscle contractility, the afterload refers to:
Your 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
- Medicine
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Question 71
Incorrect
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Blood flow to the subendocardial portions of the left ventricular muscle occurs mainly during:
Your Answer: Isovolumetric ventricular contraction
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
- Medicine
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Question 72
Correct
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Which of the following has the shortest duration:
Your Answer: Atrial systole
Explanation:Atrial systole: 0.1s
Atrial diastole: around 0.4s
Ventricular diastole: 0.4-0.53s
Ventricular systole: 0.27s
PR interval: 0.12-0.2 s
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 73
Correct
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Question 74
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
- Medicine
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Question 75
Incorrect
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Concerning surface anatomy, where is the mitral valve found?
Your Answer: Situated in the 4th intercostal space in the mid clavicular line
Correct Answer: Situated in the 4th intercostal space to the left of the sternum
Explanation:The mitral valve is situated in the left 4th intercostal space just beneath the sternum.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 76
Incorrect
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Catecholamines…
Your Answer: Are both positive ionotropic and negative chronotropic
Correct Answer: Activate adenylyl cyclase
Explanation:Norepinephrine and epinephrine activate or deactivate adenylyl cyclase resulting in a decrease or an increase in the production of cAMP.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 77
Incorrect
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Calcium needed for cardiac muscle contraction is made available during which phase of the action potential?
Your Answer: 1
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
- Medicine
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Question 78
Incorrect
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In the Fick‘s method of measuring cardiac output, the arterial oxygen content can be measured in a sample obtained from
Your Answer: The left ventricle
Correct Answer: The pulmonary vein
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.Note that (Ca – Cv) is also known as the arteriovenous oxygen difference.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 79
Correct
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Initial depolarization of cardiac muscle is due to influx of:
Your Answer: Na+
Explanation:Initial depolarization of the cardiac muscle results from opening of the sodium voltage gated channels. This results in the influx of sodium and an increase in the membrane potential towards threshold. Potassium efflux results in repolarization.
The cardiac action potential has 5 phases:
- Phase 0—depolarization because of the opening of fast sodium channels. Potassium flux also decreases.
- Phase 1—partial repolarization because of a rapid decrease in sodium ion passage as fast sodium channels close.
- Phase 2—plateau phase in which the movement of calcium ions out of the cell, maintains depolarization.
- Phase 3—repolarization, sodium, and calcium channels all close and membrane potential returns to baseline.
- Phase 4—resting membrane potential (−90 mV), resulting from the activity of the Na+/K+ ATPase pump which creates a negative intracellular potential because of the exchange of three sodium ions for only two potassium ions.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 80
Incorrect
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Myocardium requires more oxygen to expel blood in:
Your Answer: An incompetent tricuspid 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
- Medicine
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Question 81
Incorrect
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Which of the following is NOT true of the parasympathetic control of the heart?
Your Answer: It affects muscarinic receptors
Correct Answer: It can be blocked by beta blockers
Explanation:Parasympathetic fibers do not innervate the Beta receptors on the heart. They are innervated by the sympathetic nerve fibers. Then a beta blocker such as propranolol will block the sympathetic outflow and increase the parasympathetic tone of the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 82
Correct
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How does pregnancy affect the cardiac output of a patient?
Your Answer: Increased cardiac output due to increase in heart rate and stroke volume
Explanation:Cardiac Output increases to a similar degree as the blood volume. During the first trimester cardiac output is 30-40% higher than in the non-pregnant state. Steady rises are shown on Doppler echocardiography, from an average of 6.7 litres/minute at 8-11 weeks to about 8.7 litres/minute flow at 36-39 weeks; they are due, primarily, to an increase in stroke volume (35%) and, to a lesser extent, to a more rapid heart rate (15%). There is a steady reduction in systemic vascular resistance (SVR) which contributes towards the hyperdynamic circulation observed in pregnancy
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 83
Correct
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The coronary arteries supply which part of the heart’s subendocardial region exclusively in diastole?
Your Answer: Left ventricle
Explanation:It is only during diastole that the blood flows to the subendocardial portion of the left ventricle, as the heart muscle relaxes and the coronary arteries regain their patency.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 84
Incorrect
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Which one of the following have not been shown to improve mortality in patients with chronic heart failure?
Your Answer: Nitrates and hydralazine
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
- Medicine
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Question 85
Incorrect
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Digoxin causes:
Your Answer: Decrease in cardiac contractility
Correct Answer: Increase in cytosolic calcium concentration
Explanation:Digoxin is a positive inotrope which inhibits NA/K ATPase, increases cardiac contractility and can cause hypokalaemia.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 86
Incorrect
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Which of the following is NOT associated with the development of aortic regurgitation?
Your Answer: Marfan's syndrome
Correct Answer: Dilated cardiomyopathy
Explanation:Aortic insufficiency, is often due to the aortic root dilation, which is idiopathic in over 80% of cases, but otherwise may result from aging, syphilitic aortitis, osteogenesis imperfecta, aortic dissection, Bechet’s disease, reactive arthritis and systemic hypertension. Additionally, aortic insufficiency has been linked to the use of some medications and other potential causes that affect the valve directly including Marfan’s syndrome, Ehlers–Danlos syndrome, ankylosing spondylitis, and systemic lupus erythematosus. In acute cases of aortic insufficiency, the main causes are infective endocarditis, aortic dissection or trauma. Dilated cardiomyopathy is associated with the development of mitral regurgitation, not aortic regurgitation
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 87
Incorrect
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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: 54 l/min
Correct 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
- Medicine
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Question 88
Correct
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Which of the following suggests the presence of mitral regurgitation as well as mitral stenosis?
Your 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
- Medicine
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Question 89
Incorrect
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What is troponin?
Your Answer: A myosin heavy chain
Correct Answer: A component of thin filaments
Explanation:Skeletal muscle cytoplasmic proteins include myosin and actin (also known as thick and thin filaments, respectively) which are arranged in a repeating unit called a sarcomere. Troponin is a component of thin filaments (along with tropomyosin), and is the protein to which calcium binds.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 90
Correct
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Question 91
Incorrect
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Nitric oxide triggers vascular smooth muscle contraction through activation of which enzyme?
Your Answer: Protein kinase a
Correct Answer: Guanylyl cyclase
Explanation:Impaired production or excess catabolism of NO impairs this endothelium-dependent vasodilator function and may contribute to excessive vasoconstriction under various pathological situations.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 92
Correct
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Angina pectoris develops when blood through the coronary artery becomes:
Your Answer: Restricted, limiting blood blow
Explanation:Angina pectoris develops when stenosis ( >70%) of the artery occurs as a result of formation of an atherosclerotic plaque. This leads to a decrease in the O2 carried to the thickened heart muscle by the blood, leading to the characteristic chest pain associated with angina pectoris.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 93
Incorrect
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Which of the following isoforms of Nitric oxide synthase (NOS) is found in endothelial cells?
Your Answer: Nos 1
Correct Answer: Nos 3
Explanation:There are only 3 isoforms:NOS 1: found in nervous systemNOS 2: in macrophages and other immune cellsNOS 3: In endothelial cells
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 94
Incorrect
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Stimulation of the carotid sinus results in:
Your Answer: Tachycardia
Correct Answer: Drop in blood pressure
Explanation:Stimulation of the carotid sinus will result in an increase in the baroreceptor discharge. This will travel via the afferent nerves to the medulla. Signals will pass through the vagus nerve to decrease the sympathetic outflow to the heart and the blood vessels. This inhibition will result in vasodilation of the blood vessels, venodilation and bradycardia hence decreasing the total peripheral resistance and lowering the blood pressure.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 95
Incorrect
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Select the correct statement regarding the 4th heart sound, it?
Your Answer: Coincides with rapid ventricular filling.
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
- Medicine
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Question 96
Correct
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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
- Medicine
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Question 97
Incorrect
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The V wave in the jugular pulse is caused by:
Your Answer: Ventricular contraction
Correct Answer: Atrial filling
Explanation:The v wave reflects the passive increase in pressure and volume of the right atrium as it fills in late systole and early diastole.
The jugular vein pulsations usually have two elevations and two troughs. The first elevation (a wave) corresponds to the slight rise in atrial pressure resulting from atrial contraction. The first descent (x descent) reflects a fall in atrial pressure that starts with atrial relaxation. The second elevation (v wave) corresponds to ventricular systole when blood is entering the right atrium from the vena cavae while the tricuspid valve is closed. Finally, the second descent (y descent) reflects falling right atrial pressure as the tricuspid valve opens and blood drains from the atrium into the ventricle.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 98
Incorrect
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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: Ventricular pressure decreases often on this portion
Correct 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
- Medicine
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Question 99
Correct
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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
- Medicine
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Question 100
Correct
SESSION STATS - PERFORMANCE PER SPECIALTY
