-
Question 1
Correct
-
Relaxation of the cardiac muscle at the actin-myosin cross bridges is initiated by binding of which molecule to the exposed site on the myosin.
Your Answer: ATP
Explanation:A crossbridge is a myosin projection, consisting of two myosin heads, that extends from the thick filaments. Each myosin head has two binding sites: one for ATP and another for actin. The binding of ATP to a myosin head detaches myosin from actin, thereby allowing myosin to bind to another actin molecule. Once attached, the ATP is hydrolysed by myosin, which uses the released energy to move into the cocked position whereby it binds weakly to a part of the actin binding site.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 2
Correct
-
Which factor produced by the endothelium is responsible for the regulation of vascular cell growth?
Your Answer: Vascular endothelial growth factor (VEGF)
Explanation:VEGF is produced by the endothelial cells and is the major growth factor responsible for causing vasculogenesis. Some isoforms of this growth factor also have a prominent role in formation of lymphatic vessels.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 3
Correct
-
Which one of the following is a risk factor for torsade de pointes?
Your 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
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 4
Incorrect
-
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: Leak of calcium from cell membranes of overstretched cardiac muscle
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 5
Correct
-
Where would one find pericytes around endothelial cells?
Your Answer: Post-capillary venules
Explanation:Pericytes release a wide variety of vasoactive agents which regulate the flow through the junction between endothelial cells.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 6
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 7
Correct
-
Which of the following isoforms of Nitric oxide synthase (NOS) is found in endothelial cells?
Your 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
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 8
Incorrect
-
Vasodilatation in skeletal muscle can be caused by:
Your Answer: Neuropeptide y
Correct Answer: Sympathetic cholinergic nerves
Explanation:In skeletal muscles some fibers that cause vasodilation run with the nerves of the sympathetic system but are cholinergic in nature. These nerves are not active during rest but become active during exercise and stress.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 9
Correct
-
The posterior aspect of the interventricular septum is supplied by:
Your Answer: A branch of the right coronary artery
Explanation:The posterior aspect of the heart is supplied by the posterior interventricular artery which is a branch of the right coronary artery.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 10
Incorrect
-
Catecholamines…
Your Answer: Inhibit Ca++ influx into myocytes
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 11
Correct
-
Angina pectoris develops when blood through the coronary artery becomes:
Your Answer: Restricted, limiting blood blow
Explanation:Angina pectoris develops when stenosis ( >70%) of the artery occurs as a result of formation of an atherosclerotic plaque. This leads to a decrease in the O2 carried to the thickened heart muscle by the blood, leading to the characteristic chest pain associated with angina pectoris.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 12
Incorrect
-
Which of the following pairs are correct concerning arteriolar tone?
Your Answer: Myogenic control: vascular smooth muscle responds to changes in pressure
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 13
Incorrect
-
Hyperkalaemia [K+ =7meq/l] can lead to the following ECG changes [Ca++ normal]
Your Answer: QRS lengthened
Correct Answer: Peaked T waves
Explanation:Hyperkalaemia causes the formation of tall tented T waves due to altered repolarization.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 14
Correct
-
Pacemaker cells in the SA node and the AV node are connected by?
Your Answer: Gap junctions
Explanation:Gap junctions allows for rapid propagation of the action potential from one cell to the other. The cells of the heart are connected by gap junctions.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 15
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 16
Correct
-
The V wave in the jugular pulse is caused by:
Your 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 17
Incorrect
-
The hyperpolarization phase of pacemaker cells is dominated by ____ current.
Your Answer: H+
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 18
Incorrect
-
Which factors increase the end-diastolic volume?
Your Answer: Infiltrative disease
Correct Answer: Constriction of veins
Explanation:End diastolic volume is also known as preload. It is the amount of blood the heart contracts against. Constriction of veins will decrease venous pooling and increase venous return, hence increasing the end diastolic volume. Standing will increase venous pooling hence decreasing venous return and end diastolic volume. Raised intrapericardial pressure will also decrease venous return and hence end diastolic volume.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 19
Correct
-
Question 20
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 21
Incorrect
-
Tunica intima is made up of?
Your Answer: Endothelial cells and smooth muscle cells
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 22
Incorrect
-
The initial rapid depolarization in the action potential of cardiac muscle cells is due to:
Your Answer: Closure of Ca2+ channels
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 23
Incorrect
-
The coronary arteries supply which part of the heart’s subendocardial region exclusively in diastole?
Your Answer: Left atrium
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 24
Incorrect
-
Excitation-contraction coupling in cardiac muscle involves all of the following except:
Your Answer: Increase in permeability of muscle fiber to Na+
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 25
Correct
-
Question 26
Correct
-
Depolarization of the T tubule membrane activates the sarcoplasmic reticulum via which receptors?
Your Answer: Dihydropyridine receptors
Explanation:Action potentials are transmitted to the fibrils of a fiber through the T tubule system. It triggers the release of Ca 2+ form the terminal cisterns. Depolarization of the T tubules activates the sarcoplasmic reticulum through the dihydropyridine receptors.
Dihydropyridine receptors (DHPRs), are voltage-gated Ca2+ channels, and ryanodine receptors (RyRs), which are intracellular Ca2+ release channels, are expressed in diverse cell types, including skeletal and cardiac muscle.
Ryanodine receptors (RyRs) are located in the sarcoplasmic/endoplasmic reticulum membrane and are responsible for the release of Ca2+ from intracellular stores during excitation-contraction coupling in both cardiac and skeletal muscle.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 27
Incorrect
-
Cholinergic nerves from the vagus innervate the SA and AV nodes via which receptor in the heart?
Your Answer: B2 receptor
Correct Answer: M2 receptor
Explanation:M2 receptor is found in the heart. M3 and M4 are associated with smooth muscle.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 28
Incorrect
-
Question 29
Incorrect
-
The principle by which the energy of contraction is proportional to the initial length of cardiac muscle fiber is known as:
Your Answer: Indicator dilution method
Correct Answer: Starling’s law
Explanation:The Frank starling relationship describes that an increase in the venous return or the end diastolic volume will cause an increase in the stroke volume/ preload and also cardiac output. It stems from the fact that increase venous return will increase the stretch on the ventricular muscle fibers. The sarcomere will stretch a considerable length that is needed for maximum contraction and increased development of tension in the muscle fiber. The greater the venous return the greater the cardiac output. This relation is directly proportional.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 30
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 31
Incorrect
-
The heart rate can be accelerated by:
Your Answer: Expiration
Correct Answer: Exercise and thyroid hormones
Explanation:The firing of the SA node will increase due to exercises and as the thyroid hormone has a chronotropic effect on the heart, it too will result in an increase in the heart rate via stimulation of the adrenergic receptors of the heart. As during exercise the sympathetic nervous system is activated, it will directly have an positive chronotropic effect on the heart.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 32
Incorrect
-
The right border of the heart corresponds to which line on the surface of the chest?
Your Answer: Line drawn from the 2nd left costal cartilage to the 5th left intercostal space
Correct Answer: Line drawn from the 3rd right costal cartilage to the 6th right costal cartilage
Explanation:The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 33
Incorrect
-
The direct determinants of cardiac output are
Your Answer: Stroke volume and peripheral resistance
Correct Answer: Stroke volume and heart rate
Explanation:Cardiac output is classically defined alongside stroke volume (SV) and the heart rate (HR) as:Cardiac Output [L/min] = Stroke Volume [L/beat] x Heart Rate [beats/min]
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 34
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 35
Incorrect
-
In the blood supply of the heart, ‘dominance’ refers to the coronary artery which supplies the?
Your Answer: Right atrium
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 36
Incorrect
-
Coronary arteries fill up during
Your Answer: Atrial systole
Correct Answer: Diastole
Explanation:During contraction of the ventricular myocardium (systole), the subendocardial coronary vessels (the vessels that enter the myocardium) are compressed due to the high ventricular pressures. This compression results in momentary retrograde blood flow (i.e., blood flows backward toward the aorta) which further inhibits perfusion of myocardium during systole. However, the epicardial coronary vessels (the vessels that run along the outer surface of the heart) remain open. Because of this, blood flow in the sub endocardium stops during ventricular contraction. As a result, most myocardial perfusion occurs during heart relaxation (diastole) when the subendocardial coronary vessels are open and under lower pressure.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 37
Incorrect
-
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 stroke volume
Correct 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
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 38
Incorrect
-
According to Starling's law of the heart:
Your Answer: Cardiac output is not affected by change in venous return
Correct Answer: The extent of the preload is proportional to the end-diastolic volume
Explanation:Frank starlings law describes that an increase in the venous return or the end diastolic volume will cause an increase in the stroke volume/ preload and also cardiac output. It stems from the fact that increased venous return will increase the stretch on the ventricular muscle fibers. The sarcomere will stretch a considerable length that is needed for maximum contraction and the development of tension in the muscle fiber. The greater the venous return the greater the cardiac output. This relationship is directly proportional.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 39
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 40
Correct
-
Question 41
Incorrect
-
Regarding blood supply to the heart;
Your Answer: There are three main coronary arteries
Correct Answer: Coronary arteries fill as the heart relaxes
Explanation:The heart muscles acts like the skeletal muscle in the fact that it also compress the vessels during contraction. As the pressure in the ventricle is slightly greater than in the aorta the coronary vessels collapse during systole. Blood flows through them during the diastole phase of contraction.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 42
Incorrect
-
The predominant receptors in the hearts conduction system are?
Your Answer: Α1
Correct Answer: Β1
Explanation:All of the components of the intrinsic conduction system contain autorhythmic cells that spontaneously depolarize. In the absence of extrinsic neural or hormonal influences, the SA node pacing rate would be about 100 beats per minute (bpm). The heart rate and cardiac output, however, must vary in response to the needs of the body’s cells for oxygen and nutrients under varying conditions. In order to respond rapidly to changing requirements of the body’s tissues, the heart rate and contractility are regulated by the autonomic nervous system (ANS), hormones, and other factors. The ANS has two interacting systems: the sympathetic and parasympathetic systems.
Sympathetic receptors: There are two types of adrenergic receptors: β and α. In the cardiovascular system there are β1, β2, α1, and α2 adrenergic receptors. β1 adrenergic receptors are expressed in the heart conduction system (in the SA node, AV node, and on atrial and ventricular cardiomyocytes). The activation of β1 receptors increases heart rate (via the SA node), and contractility.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 43
Incorrect
-
The coronary arteries fill during?
Your Answer: Occlusion by valve cusps
Correct Answer: Diastole
Explanation:During systole the coronary arteries collapse as a result of the pressure due to contraction that is exerted on them. During diastole the heart muscle relaxes and the pressure on the coronary vessels is relieved allowing blood to flow through them to the subendocardium.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 44
Correct
-
In a 30 year old male with hypertrophic obstructive cardiomyopathy (HOCM), which of the following is not associated with increased risk of sudden death?
Your Answer: Age
Explanation:Hypertrophic cardiomyopathy (HCM) is a disease in which a portion of the myocardium (heart muscle) is enlarged without any obvious cause, creating functional impairment of the heart. It is the leading cause of sudden death in young athletes. The major risk factors for sudden death (SD) are recent unexplained syncope unlikely to be neurocardiogenic; HCM-related SD in first-degree or other close relatives; repetitive and/or prolonged nonsustained ventricular tachycardia (NSVT) episodes on Holter or extended ambulatory monitoring; massive left ventricular hypertrophy (LVH) (wall thickness ≥30 mm); extensive/diffuse late gadolinium enhancement (LGE); end-stage heart failure usually with systolic dysfunction; and thin-walled akinetic LV apical aneurysm with regional scarring.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 45
Incorrect
-
Where would one normally find venous valves?
Your Answer: Inferior vena cava
Correct Answer: Saphenous vein
Explanation:The intima of the limb veins is folded at intervals to form venous valves that prevent retrograde flow. There are no valves present in the very small veins, the great veins, or the veins in the brain and viscera.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 46
Incorrect
-
Concerning surface anatomy, where is the base of the heart
Your Answer: 5th intercostal space mid clavicular line
Correct Answer: 2nd left costal to 3rd right costal cartilage
Explanation:The base of the heart, also known as the superior border of the heart corresponds to a line connecting the inferior border of the 2nd left costal cartilage to the superior border of the 3rd right costal cartilage.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 47
Incorrect
-
Nitric oxide triggers vascular smooth muscle contraction through activation of which enzyme?
Your Answer: Adenylate cyclase
Correct Answer: Guanylyl cyclase
Explanation:Impaired production or excess catabolism of NO impairs this endothelium-dependent vasodilator function and may contribute to excessive vasoconstriction under various pathological situations.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 48
Incorrect
-
Although variable, branches of which artery most often supply the SA and AV nodes?
Your Answer: Left coronary artery
Correct Answer: Right coronary artery
Explanation:The RCA (right coronary artery) supplies the SA and the AV nodes along with the postero-basal wall of the left ventricle, posterior one third of the inferior vena cava, right ventricle and the posteromedial papillary muscle in the left ventricle.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 49
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 50
Incorrect
-
Which of the following antiarrhythmic drugs may be used in the treatment of long QT syndrome?
Your Answer: Propafenone
Correct Answer: Atenolol
Explanation:Beta-blockers are the mainstay of treatment in long QT syndrome. Implantable cardioverter-defibrillators are the most effective treatment in genotypes with a high risk of recurrence.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 51
Correct
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 52
Incorrect
-
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: 15 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 53
Incorrect
-
Which of the following are responsible for the 4th heart sound?
Your Answer: Closure of the atrio-ventricular valves
Correct Answer: Ventricular hypertrophy
Explanation:The fourth heart sound is not normally audible in a normal adult. It occurs as a consequence of ventricular hypertrophy. It is caused by filling of the ventricle in atrial systole.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 54
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 55
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 56
Incorrect
-
The ability of the SA node cells to allow ionic flow through channels activated in a hyperpolarized state is known as:
Your Answer: Non of the above
Correct Answer: Pace maker potential
Explanation:Rhythmically discharging cells have a membrane potential that, after each impulse, declines to the firing level. Thus this prepotential or Pacemaker potential triggers the next impulse. The inherent leakiness of the sinus nodal fibers to Na+ and Ca2+ causes their self excitation.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 57
Correct
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 58
Incorrect
-
Arterioles stemming from the coronary artery can also empty into the heart directly via the:
Your Answer: AV fistulas
Correct Answer: Arteriosinusoidal vessels
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. They include arteriosinusoidal vessels, which connect the arterioles to the heart chambers. The thebesian veins drain the capillaries into the chambers and the arterioluminal vessels drain small arteries directly into the chambers.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 59
Incorrect
-
Regarding the length of systole and diastole which of the following is true?
Your Answer: At very rapid heart rates diastole is adequate
Correct Answer: The duration of systole is more fixed than diastole
Explanation:The duration of systole is more fixed than the duration of diastole. When the heart rate increases the timing of systole remains more or less the same however, diastole decreases.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 60
Incorrect
-
Which of the following phases in depolarization and repolarization of cardiac muscle cells are caused by the inactivation of Na+ channels?
Your Answer: Phase 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 61
Incorrect
-
What is the isolated effect of B2 stimulation on the coronaries?
Your Answer: The coronary arteries have no B2 receptors
Correct Answer: Vasodilatation
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 beta. 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 62
Incorrect
-
In cardiac muscle, which of the following is directly responsible for the release of Ca2+ stored in the sarcoplasmic reticulum (calcium-induced calcium release)?
Your Answer: Dihydropyridine receptors (DHPR)
Correct Answer: Ryanodine receptor (RyR)
Explanation:Ryanodine receptor (RyR) is a ligand-gated Ca2+ channel with Ca2+ as its natural ligand. In skeletal muscle, Ca2+ entry from ECF by this route is not required for Ca2+ release. Instead, the DHPR that serves as the voltage sensor unlocks release of Ca2+ from the nearby SR via physical interaction with the RyR. The release is amplified through ca-induced ca release. However, in cardiac muscle, it is the influx of extracellular Ca2+ through the voltage-sensitive DHPR in the T system that triggers ca-induced ca release trough the RyR at the SR.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 63
Incorrect
-
A sarcomere is the area between:
Your Answer: Two adjacent a bands
Correct Answer: Two adjacent z lines
Explanation:The area that lies between the two adjacent Z lines is known as a sarcomere and is the contractile unit of the muscle. The line passing in the middle of the myosin filaments is the M line. It also passes through the middle of the sarcomere.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 64
Incorrect
-
The isoforms of nitric oxide synthase which are found in the nervous system (NOS1) and endothelial cells (NOS3) are activated by agents that increase which of the following intracellular electrolytes?
Your Answer: K
Correct Answer: Ca
Explanation:Synthesis of nitric oxide is stimulated by activation of the NMDA receptors by certain agents. This leads to opening of the Calcium channels and an influx of calcium into the cell. This will activate the nitric oxide synthase. Nitric oxide is produced on demand.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 65
Incorrect
-
Which of the following structures of the cardiac conduction system is located in the right posterior portion of the interatrial septum?
Your Answer: Bundle of his
Correct Answer: AV node
Explanation:AV node is located at the right posterior portion of the interatrial septum.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 66
Incorrect
-
The following is true of the sinus node:
Your Answer: It discharges at a rate of 80-100 bpm
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 67
Correct
-
Where does the SA node develop?
Your Answer: From structures on the right side of the embryo.
Explanation:The SA node develops from the right side of the embryo and the AV node from the left. This is the reason why in adults the right vagus supplies the SA node and the left vagus supplies the AV node.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 68
Incorrect
-
In which organ will you find extremely porous sinusoidal capillaries, with discontinuous endothelium?
Your Answer: Intestine
Correct Answer: Liver
Explanation:The liver is the organ which contains sinusoidal capillaries with discontinuous endothelium. The brain, lungs and the intestine all contain continuous capillaries, however the kidney contains fenestrated capillaries to aid in filtration.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 69
Correct
-
Which of the atrial pressure changes represents the a-wave of the JVP
Your 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 70
Correct
-
Which of the following causes the closure of the ductus arteriosus during birth?
Your Answer: Reduced levels of prostaglandins
Explanation:Ductus arteriosus is kept open by the prostaglandin E2 which is a vasodilator. At birth the high levels of cyclooxygenase blocks the production of prostaglandins which results in the closure of the ductus arteriosus.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 71
Correct
-
Question 72
Correct
-
Question 73
Correct
-
The Plateau phase in myocyte action potentials does all of the following except:
Your Answer: It allows early reactivation of the myocytes
Explanation:The presence of the plateau in the action potential causes ventricular contraction to last as much as 15 times longer in cardiac muscle as in skeletal muscle. The plateau phase which follows is unique to myocytes and results from a small, but sustained inward calcium current through L-type calcium channels lasting 200-400 ms. This calcium influx is caused by a combined increase in permeability of the cell and especially the sarcolemmal membranes to calcium. This plateau (refractory) phase prevents early reactivation of the myocytes and directly determines the strength of contraction.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 74
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 75
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 76
Incorrect
-
Myocardial contractility is improved by:
Your Answer: Procainamide
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 77
Incorrect
-
Vasodilatation of coronary arteries is caused by:
Your Answer: Hypothermia
Correct Answer: Hypoxia
Explanation:The heart is highly metabolically active and boasts the highest oxygen consumption by mass of any organ. This demand for oxygen is met by the coronary circulation, which is responsible for delivering blood to the myocardium and represents approximately 5% of cardiac output. Vasodilation may be due to the local effect of hypoxia on coronary vessels, or local metabolic vasodilation, or the activation of β-adrenoceptors or some combination of these mechanisms.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 78
Incorrect
-
Concerning S3, which of the following statements is INCORRECT?
Your Answer: Normal in children
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 79
Incorrect
-
The interventricular septum is supplied anteriorly by the?
Your Answer: Circumflex artery
Correct Answer: Left anterior descending artery
Explanation:The anterior interventricular artery or left anterior descending artery supplies the anterior 2/3rds of the interventricular septum.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 80
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 81
Correct
-
Question 82
Incorrect
-
Which of the following components regulate cardiac output?
Your Answer: Afterload and preload
Correct Answer: All of the above
Explanation:Cardiac output is regulated by the autonomic nervous system with sympathetic nerves having a positive chronotropic and inotropic effect and parasympathetic nerves having the opposite effect. An increase in preload will increase cardiac output likewise an afterload increase will also increase cardiac output.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 83
Incorrect
-
In a normal heart rate at rest, the left ventricular end-diastolic volume is ….
Your Answer: 10-30 ml
Correct Answer: 100-130 ml
Explanation:In cardiovascular physiology, end-diastolic volume (EDV) is the volume of blood in the right and/or left ventricle at end load or filling in (diastole) or the amount of blood in the ventricles just before systole. Because greater EDVs cause greater distention of the ventricle, EDV is often used synonymously with preload, which refers to the length of the sarcomeres in cardiac muscle prior to contraction (systole). End-diastolic volume: Right = 144 mL(± 23mL) & Left = 142 mL (± 21 mL).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 84
Incorrect
-
Concerning surface anatomy, where is the apex beat found?
Your Answer: 6th intercostal space mid clavicular line
Correct Answer: 5th intercostal space mid clavicular line
Explanation:The location of the apex beat may vary but it is mostly found in the left 5th intercostal space 6 cm from the anterior median line or in the mid clavicular line.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 85
Incorrect
-
The postextrasystolic potentiation of myocardial contractility is due to:
Your Answer: Increased myocardial fiber length
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 86
Incorrect
-
Calcium is mobilized from the sarcoplasmic reticulum through:
Your Answer: Na/k ATPase pump
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 87
Incorrect
-
Question 88
Incorrect
-
Myocardium requires more oxygen to expel blood in:
Your Answer: None of the above
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 89
Incorrect
-
Regarding the myofilament molecules, which of the following contains binding sites for calcium that helps to initiate contraction?
Your Answer: Titin
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 90
Incorrect
-
Xanthines such as caffeine and theophylline are positively inotropic due to:
Your Answer: Circulating catecholamines
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 91
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 92
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 93
Incorrect
-
Which of the following is a method for measurement of cardiac output?
Your Answer: Swan-ganz catheterization
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 94
Incorrect
-
Regarding the surface anatomy of the orifices of the heart, where is the aortic valve located?
Your Answer: Opposite the right 3rd intercostal space
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 95
Incorrect
-
The major factor in controlling coronary artery blood flow is considered to be?
Your Answer: Sympathetic input
Correct Answer: Metabolites of oxygen consumption
Explanation:There is a strong relationship between myocardial blood flow and oxygen consumption. This indicates that products of metabolism may cause vasodilation of the coronary artery.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 96
Incorrect
-
Which of the following is NOT associated with the development of aortic regurgitation?
Your Answer: Bechet's disease
Correct Answer: Dilated cardiomyopathy
Explanation:Aortic insufficiency, is often due to the aortic root dilation, which is idiopathic in over 80% of cases, but otherwise may result from aging, syphilitic aortitis, osteogenesis imperfecta, aortic dissection, Bechet’s disease, reactive arthritis and systemic hypertension. Additionally, aortic insufficiency has been linked to the use of some medications and other potential causes that affect the valve directly including Marfan’s syndrome, Ehlers–Danlos syndrome, ankylosing spondylitis, and systemic lupus erythematosus. In acute cases of aortic insufficiency, the main causes are infective endocarditis, aortic dissection or trauma. Dilated cardiomyopathy is associated with the development of mitral regurgitation, not aortic regurgitation
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 97
Incorrect
-
The triangle with the heart at its centre, using limb leads is called:
Your Answer: Bornholm
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 98
Incorrect
-
The steps of cardiac cycle in sequence are:
Your Answer: Ejection, isovolumetric relaxation, passive ventricular filling, isovolumetric contraction, active ventricular filling.
Correct Answer: Isovolumic contraction, ejection, isovolumic relaxation, passive ventricular filling, active ventricular filling.
Explanation:The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat, and so includes the diastole, the systole, and the intervening pause.1st stage: diastole, or passive filling is when the semilunar valves (the pulmonary valve and the aortic valve) close, the atrioventricular (AV) valves (the mitral valve and the tricuspid valve) open, and the whole heart is relaxed. 2nd stage: atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle (active filling).3rd stage: isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. 4th stage: ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. 5th stage: isovolumic relaxation time, pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 99
Incorrect
-
The rate of depolarization of the SA node membrane potential is modulated by the following:
Your Answer: Autonomic tone
Correct Answer: All of the above
Explanation:Rate of depolarization of the SA node is modulated by all of these.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 100
Incorrect
-
The approximate incidence of deep venous thrombosis (DVT) in the general population each year is:
Your Answer: 10 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 101
Incorrect
-
Which of the following regulates the calcium release channels?
Your Answer: Both a and d
Correct Answer: Calstabin 2
Explanation:Ca2+ is released from the SR through a Ca2+ release channel, a cardiac isoform of the ryanodine receptor (RyR2), which controls intracytoplasmic [Ca2+] and, as in vascular smooth-muscle cells, leads to the local changes in intracellular [Ca2+] called calcium sparks. A number of regulatory proteins, including calstabin 2, inhibit RyR2 and, thereby, the release of Ca2+ from the SR.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 102
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 103
Incorrect
-
If both the noradrenergic and the cholinergic systems are blocked in the heart, the rate will be approximately:
Your Answer: 140/min
Correct Answer: 100/min
Explanation:The normal heart beat is about 70/min. This is due to a predominant parasympathetic activity. If sympathetic activity was unopposed the heart rate would have been 150/min. When both the noradrenergic and cholinergic systems are blocked the heart rate is 100/min. This is the normal firing rate of the SA node.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 104
Correct
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 105
Incorrect
-
The T-tubular system in cardiac muscle is:
Your Answer: Has dihydropyridine receptors which act as calcium activated Ca2+ release channels.
Correct Answer: Transmits action potential from sarcolemma to the SR to allow for Ca2+ release into the cytoplasm
Explanation:Action potentials are transmitted to the fibrils of a fiber through the T tubule system. It triggers the release of Ca 2+ from the terminal cisterns. Depolarization of the T tubules activates the sarcoplasmic reticulum through the dihydropyridine receptors, which are voltage gated calcium channels.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 106
Incorrect
-
Question 107
Incorrect
-
The following is true in relation to coronary venous drainage?
Your Answer: Drains into SVC and IVC respectively
Correct Answer: Most venous return ultimately drains into right atrium via the coronary sinus
Explanation:Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 108
Incorrect
-
The process by which depolarization of the muscle fiber initiates contraction is called?
Your Answer: Dystrophin-glycoprotein coupling
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 109
Incorrect
-
Where are the baroreceptors of the great arteries located?
Your Answer: In the endothelium
Correct Answer: In the adventitia
Explanation:Arterial baroreceptors are located in the aortic arch and carotid sinuses, and are formed by small nerve endings present in the adventitia of these vessels.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 110
Correct
-
Which of the following is true of the Natriuretic hormones?
Your Answer: They are released in response to hypervolemia
Explanation:Natriuretic hormones are vasodilators released in response to hypervolemia.
Natriuretic hormones (NH) include three groups of compounds: the natriuretic peptides NPs (ANP, BNP and CNP), the gastrointestinal peptides (guanylin and uroguanylin), and endogenous cardiac steroids. These substances induce the kidney to excrete sodium and therefore participate in the regulation of sodium and water homeostasis, blood volume, and blood pressure (BP). In addition to their peripheral functions, these hormones act as neurotransmitters or neuromodulators in the brain.
Atrial natriuretic peptide (ANP) plays a crucial role in blood pressure regulation by inducing natriuresis and diuresis in the kidney, inhibiting renin secretion, aldosterone production, and promoting vasorelaxation. Two paracrine factors derived from endothelial cells play important roles in modulating ANP secretion. Endothelin, a potent vasoconstrictor, stimulates ANP secretion and augments stretch induced ANP secretion. The dramatic increase in ANP release produced by cardiac ischemia appears to be mediated in part by endothelin. Nitric oxide (NO), an important vasodilator, is also produced by endothelial cells and inhibits ANP secretion.
Brain natriuretic peptide (BNP) shares ANP’s receptor but is primarily associated with antifibrotic effects in ventricular remodeling, serving as a biomarker for heart failure and myocardial infarction.
C-type natriuretic peptide (CNP) acts locally in an autocrine/paracrine manner, exerting potent cardiovascular effects, including vasorelaxation and vascular remodeling post-injury. NPs also demonstrate diverse effects beyond cardiovascular and renal systems, such as bronchodilation, anti-inflammatory actions, and metabolic effects on adipose tissue and long bones.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 111
Incorrect
-
Digoxin causes:
Your Answer: Na/k ATPase stimulation
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 112
Incorrect
-
Which membrane bound protein in the sarcoplasmic reticulum regulates calcium return from the cytosol to the sarcoplasmic reticulum?
Your Answer: Camp
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).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 113
Incorrect
-
Regarding cardiac output, an increased ejection fraction results from increases in which of the following?
Your Answer: Strength of contraction with increase in muscle fiber length
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 114
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 115
Correct
-
B1 adrenergic stimulation produces:
Your 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 116
Incorrect
-
Which ion channel does not contribute to the myocardial action potential?
Your Answer: Transient type and long type calcium channels
Correct Answer: Chloride channel
Explanation:The upstroke in the cardiac action potential is due to opening of the sodium channels and an influx of sodium into the cell. The initial repolarization phase is due to transient opening of the potassium channels along with calcium channels. Influx of calcium causes the prolonged plateau phase of the action potential. Delayed opening of the rectifier potassium channel and delayed closure of the calcium channel leads to the repolarization phase of cardiac action potential.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 117
Incorrect
-
With regard to the endothelial structure, the epithelium constitute:
Your Answer: Stratified squamous
Correct Answer: Simple squamous
Explanation:The single layer of squamous epithelium lining the heart and blood vessels is known as the endothelium.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 118
Incorrect
-
Cholinergic vagal supply to the SA and AV nodes results in slowing of the heart rate via:
Your Answer: B2 receptors
Correct Answer: M2 muscarinic receptors
Explanation:M2 muscarinic receptors are the receptors for the parasympathetic system to the SA and the AV node.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 119
Correct
-
The coronary sinus drains into the:
Your Answer: Right atrium
Explanation:The coronary sinus drains into the right atrium. Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 120
Incorrect
-
Which of the following is the most common causative organism in infective endocarditis?
Your Answer: Staphylococcus aureus
Correct 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
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 121
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 122
Incorrect
-
Depolarization spreads rapidly through cardiac muscle fibers because of the presence of:
Your Answer: Adherent junctions
Correct Answer: Gap junctions
Explanation:The cardiac muscles have gap junctions in between the cells. They allow for the formation of low resistance passages, which allow ions to diffuse through every muscle fiber rapidly and result in the cardiac muscles functioning as a syncytium, without any protoplasmic bridges involved.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 123
Incorrect
-
In which area is depolarization initiated?
Your Answer: AV node
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 124
Incorrect
-
Which of the following does not contribute to increased stroke volume during exercise?
Your Answer: Increased end-diastolic volume
Correct Answer: Increased length of filling time during diastole
Explanation:Prolonged aerobic exercise training may also increase stroke volume, which frequently results in a lower (resting) heart rate. Reduced heart rate prolongs ventricular diastole (filling), increasing end-diastolic volume, and ultimately allowing more blood to be ejected.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 125
Incorrect
-
In ventricular fibrillation (VF), the first defibrillation attempt (with a biphasic defibrillator) should be made at:
Your Answer: 400 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 126
Incorrect
-
Question 127
Incorrect
-
Concerning surface anatomy, where is the mitral valve found?
Your Answer: Situated in the 4th intercostal space to the right of the sternum
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 128
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 129
Incorrect
-
Which of the following intercellular connections is important in endothelial barrier function?
Your Answer: Gap junctions
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 130
Incorrect
-
The internodal tract of Bachman:
Your Answer: Its main function is to reduce the amount of conduction to the AV node
Correct Answer: Connects the SA node to the AV node
Explanation:Internodal tract of Bachman connects the SA node to the AV node conducting the electrical impulses generated from the SA node to the AV node and from the AV node to the rest of the electrical complex of the heart.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 131
Correct
-
The rate of depolarisation of the sinus node membrane potential is modulated by all the following except:
Your Answer: Cardiac output
Explanation:Cardiac output has no effect on the depolarization of the pacemaker potential of the heart.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 132
Correct
-
Which is the commonest cardiovascular abnormality seen in an adult patient with Marfan’s syndrome?
Your Answer: Aortic aneurysm
Explanation:Marfan syndrome (MFS) is a genetic disorder of connective tissue. The degree to which people are affected varies. People with Marfan’s tend to be tall, and thin, with long arms, legs, fingers and toes. They also typically have flexible joints and scoliosis. The most serious complications involve the heart and aorta with an increased risk of mitral valve prolapse and aortic aneurysm.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 133
Correct
-
The function of Troponin T in cardiac muscle is?
Your 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 134
Incorrect
-
Initial depolarization of cardiac muscle is due to influx of:
Your Answer: Mg++
Correct Answer: Na+
Explanation:Initial depolarization of the cardiac muscle results from opening of the sodium voltage gated channels. This results in the influx of sodium and an increase in the membrane potential towards threshold. Potassium efflux results in repolarization.
The cardiac action potential has 5 phases:
- Phase 0—depolarization because of the opening of fast sodium channels. Potassium flux also decreases.
- Phase 1—partial repolarization because of a rapid decrease in sodium ion passage as fast sodium channels close.
- Phase 2—plateau phase in which the movement of calcium ions out of the cell, maintains depolarization.
- Phase 3—repolarization, sodium, and calcium channels all close and membrane potential returns to baseline.
- Phase 4—resting membrane potential (−90 mV), resulting from the activity of the Na+/K+ ATPase pump which creates a negative intracellular potential because of the exchange of three sodium ions for only two potassium ions.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 135
Incorrect
-
Cross-bridges between actin and myosin filaments contain:
Your Answer: cAMP
Correct Answer: Calcium ions
Explanation:At rest troponin I is bound to actin and tropomyosin and covers the site where the myosin head interacts with actin. When calcium enters into the muscle, it binds with troponin C and causes a structural change in troponin I which moves out of the myosin binding site and causes the cross bridges between the actin and myosin filaments to occur.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 136
Correct
-
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: 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 137
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 138
Incorrect
-
Which of the following corresponds to an oblique line drawn from the sternal end of the left 3rd costal cartilage to the sternal end of the right 6th costal cartilage?
Your Answer: 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 139
Incorrect
-
The following contributes to the rate of depolarization?
Your Answer: pH
Correct Answer: All of the options given
Explanation:Depolarization occurs due to impulses generated by the SA node. As the heart beats to the rhythm of the SA node, certain factors will effect the rate of depolarization. All the mentioned options effect the rate of depolarization.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 140
Incorrect
-
All valves are closed in which phase of the cardiac cycle?
Your Answer: Ejection phase
Correct Answer: Isovolumetric relaxation
Explanation:The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat, and so includes the diastole, the systole, and the intervening pause.The first stage, diastole, is when the semilunar valves (the pulmonary valve and the aortic valve) close, the atrioventricular (AV) valves (the mitral valve and the tricuspid valve) open, and the whole heart is relaxed. The second stage, atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle.The third stage, isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. The fourth stage, ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. During the fifth stage, isovolumic relaxation time, pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 141
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 is equal to systole
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 142
Incorrect
-
The areas of extensive series of sarcoplasmic folds known as intercalated discs always occur at what portion of the muscle fiber?
Your Answer: A band
Correct Answer: Z lines
Explanation:The muscle fibers of the heart branch and interdigitate, but one complete unit is surrounded by a cell membrane. The place where one muscle fiber abuts the other, the cell membrane of both the fibers run parallel to each other through a series of extensive folds. These areas always occur on the Z lines and are known as intercalated discs.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 143
Incorrect
-
When looking at the JVP what does the c wave signify:
Your Answer: Atrial systole
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 144
Incorrect
-
Stimulation of the carotid sinus results in:
Your Answer: Cyanosis
Correct Answer: Drop in blood pressure
Explanation:Stimulation of the carotid sinus will result in an increase in the baroreceptor discharge. This will travel via the afferent nerves to the medulla. Signals will pass through the vagus nerve to decrease the sympathetic outflow to the heart and the blood vessels. This inhibition will result in vasodilation of the blood vessels, venodilation and bradycardia hence decreasing the total peripheral resistance and lowering the blood pressure.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 145
Incorrect
-
Transport of Ca2+ into the reticulum to initiate cardiac muscle relaxation in via:
Your Answer: Voltage-gated Ca2+ channels
Correct Answer: Serca (sarcoplasmic or endoplasmic reticulum Ca2+ ATPase)
Explanation:Phosphorylation of phospholamban, which increases calcium ATPase activity and sequestration of calcium in the sarcoplasmic reticulum. An increased rate of relaxation is explained because cAMP also activates the protein phospholamban, situated on the membrane of the SR, that controls the rate of uptake of calcium into the SR. The latter effect explains enhanced relaxation (lusitropic effect).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 146
Incorrect
-
What are the diagnostic criteria for an ST segment elevation type of acute myocardial infarction?
Your Answer: Epstein's anomaly
Correct Answer: 1 mm ST elevation in 2 limb leads
Explanation:The current guidelines for the ECG diagnosis of the ST segment elevation type of acute myocardial infarction require at least 1 mm (0.1 mV) of ST segment elevation in the limb leads, and at least 2 mm elevation in the precordial leads. These elevations must be present in anatomically contiguous leads. (I, aVL, V5, V6 correspond to the lateral wall; V3-V4 correspond to the anterior wall ; V1-V2 correspond to the septal wall; II, III, aVF correspond to the inferior wall.)
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 147
Incorrect
-
Sinus bradycardia may be caused by disease of which of the following:
Your Answer: Circumflex artery
Correct Answer: Right coronary artery
Explanation:Disease of the right coronary artery may cause sinus bradycardia and AV nodal block.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 148
Incorrect
-
In the jugular venous pressure wave…
Your Answer: Consists of 3 troughs and 3 peaks
Correct Answer: Consists of 3 peaks and 2 troughs
Explanation:The jugular venous pressure (JVP, sometimes referred to as jugular venous pulse) is the indirectly observed pressure over the venous system via visualization of the internal jugular vein. It can be useful in the differentiation of different forms of heart and lung disease. Classically three upward deflections (peaks) and two downward deflections (troughs) have been described:The upward deflections are the a (atrial contraction), c (ventricular contraction and resulting bulging of tricuspid into the right atrium during isovolumetric systole) and v = venous filling.The downward deflections of the wave are the x (the atrium relaxes and the tricuspid valve moves downward) and the y descent (filling of ventricle after tricuspid opening).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 149
Incorrect
-
Water hammer pulse is found in:
Your Answer: Mitral incompetence
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 150
Incorrect
-
Which one of the following have not been shown to improve mortality in patients with chronic heart failure?
Your Answer: Enalapril
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)
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 151
Incorrect
-
Regarding cardiac contractility, catecholamines exert their inotropic effect via:
Your Answer: Reduced intracellular Ca2+
Correct Answer: Β1-adrenergic receptors and gs
Explanation:Catecholamines exert their inotropic effect on the heart via the B1 adrenergic receptors and Gs, stimulating adenyl cyclase and increasing the production of cAMP.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 152
Correct
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 153
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 154
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 155
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 156
Incorrect
-
Coronary blood flow occurs in?
Your Answer: Corresponds with the QRS complex on ECG
Correct Answer: Diastole
Explanation:Coronary arteries are unique in that they fill during diastole, when not occluded by valve cusps nor compressed by myocardial contraction).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 157
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 158
Incorrect
-
Which of the following statements is true regarding pulsus alternans?
Your Answer: The pulse is irregular
Correct Answer: It is found in association with a third heart sound
Explanation:Pulsus alternans is a physical finding with arterial pulse waveform showing alternating strong and weak beats. It is almost always indicative of left ventricular systolic impairment, and carries a poor prognosis. A pathological third heart sound is usually associated.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 159
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 160
Incorrect
-
Endothelial cells are attached to adjacent cells by adherent junctions via:
Your Answer: Mucins
Correct Answer: Cadherins
Explanation:Cadherins are calcium dependant molecules that mediate cell to cell adhesions in epithelial and endothelial cells among others.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 161
Correct
-
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).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 162
Incorrect
-
Question 163
Correct
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 164
Incorrect
-
Afferent fibers from the baroreceptors of the great arteries form branches of which cranial nerves?
Your Answer: Vagus and hypoglossal nerve
Correct Answer: Glossopharyngeal and vagus nerves
Explanation:The receptors of the carotid sinus are innervated by the carotid sinus nerve, a branch of the glossopharyngeal nerve. The aortic arch receptors located in the arch of the aorta are innervated by the aortic depressor nerve, a branch of the vagus nerve.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 165
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 0
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 166
Correct
-
Question 167
Incorrect
-
Stroke volume in a average sized man lying in supine position is about?
Your Answer: 100ml
Correct Answer: 70 ml
Explanation:The stroke volume of an average sized man who is lying is the supine position is about 70 ml.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 168
Incorrect
-
The following products of the vascular endothelium produce vasodilation except:
Your Answer: Vascular endothelial growth factor
Correct Answer: Endothelin
Explanation:Endothelin: This is incorrect in the context of vasodilation. Endothelin is actually a potent vasoconstrictor produced by the endothelium, leading to the narrowing of blood vessels and increased blood pressure.
Nitrous oxide (Nitric oxide): This is correct for vasodilation. Nitric oxide is a powerful vasodilator produced by the endothelium, which helps relax and widen blood vessels.
Prostacyclin: This is correct for vasodilation. Prostacyclin (PGI2) is a vasodilator and inhibits platelet aggregation, helping to maintain blood flow and reduce clot formation.
Endothelial-derived hyperpolarizing factor (EDHF): This is correct for vasodilation. EDHF causes vasodilation by hyperpolarizing the smooth muscle cells of blood vessels.
Vascular endothelial growth factor (VEGF): This is correct for vasodilation. VEGF primarily promotes the growth of new blood vessels but also has vasodilatory effects through nitric oxide production.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 169
Incorrect
-
Which of the following best describes the cardiac muscle?
Your Answer: Smooth 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 170
Incorrect
-
The following determines the strength of contraction
Your Answer: Depolarization
Correct Answer: Plateau phase
Explanation:The plateau phase which follows is unique to myocytes and results from a small, but sustained inward calcium current through L-type calcium channels lasting 200-400 ms. This calcium influx is caused by a combined increase in permeability of the cell and especially the sarcolemmal membranes to calcium. This plateau (or refractory) phase in myocyte action potential prevents early reactivation of the myocytes and directly determines the strength of contraction
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 171
Correct
-
Which one of the following is a cause of a soft second heart sound?
Your Answer: Aortic stenosis
Explanation:Second heart sound (S2) forms the dub of lub-dub and is composed of components A2 and P2. • loud: hypertension• soft: AS• fixed split: physiological split (normally occurs during inhalation), right bundle branch block, pulmonary stenosis, and atrial septal defect.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 172
Incorrect
-
What is the effect of catecholamines (i.e. increased heart rate) on the pressure volume loop?
Your Answer: Left ventricular end diastolic volume is unchanged
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 173
Incorrect
-
When is the blood pressure at its lowest during pregnancy?
Your Answer: During ovulation
Correct Answer: Second trimester
Explanation:It is lowest during the second trimester.
Previous studies have reported changes in blood pressure (BP) throughout pregnancy, and it was generally accepted that in clinically healthy pregnant women, BP falls gradually at first trimester, reaching the lowest around 22–24 weeks, rising again from 28 weeks, and reaching preconception levels by 36 weeks of gestation
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 174
Incorrect
-
The positive inotropic effect of digoxin is due to?
Your Answer: Increased intracellular c amp
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).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 175
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 176
Incorrect
-
When observing a JVP, which of the following would lead to prominent v waves?
Your Answer: Constrictive pericarditis
Correct Answer: Tricuspid regurgitation
Explanation:The v wave corresponds to Venous filling when the tricuspid valve is closed and venous pressure increases from venous return. In Tricuspid regurgitation there is additional blood from the regurgitant flow and thus this leads to a more prominent V wave.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 177
Incorrect
-
Which coronary artery supplies the right atria?
Your Answer: Circumflex
Correct Answer: Right coronary
Explanation:The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum. The circumflex artery arises from the left coronary artery and follows the coronary sulcus to the left. Eventually, it will fuse with the small branches of the right coronary artery. The right coronary artery proceeds along the coronary sulcus and distributes blood to the right atrium, portions of both ventricles, and the heart conduction system.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 178
Correct
-
Which of the following occurs during a Valsalva manoeuvre?
Your 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 179
Incorrect
-
Generalized vasoconstrictors include:
Your Answer: Carbon monoxide, prostacyclin, catecholamines
Correct Answer: Norepinephrine, endothelin, angiotensin ii
Explanation:Vasopressin, angiotensin II, adrenaline and endothelin are generalized vasoconstrictors.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 180
Incorrect
-
The bradycardia that occurs in patients with raised intracranial pressure is a result of the?
Your Answer: Somatosympathetic reflex
Correct 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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 181
Incorrect
-
Calcium induced calcium release occurs in the sarcoplasmic reticulum by activation of which receptors
Your Answer: Alpha receptors
Correct Answer: Ryanodine receptors
Explanation:Calcium-induced calcium release (CICR) describes a biological process whereby calcium is able to activate calcium release from intracellular Ca2+ stores (e.g., endoplasmic reticulum or sarcoplasmic reticulum). CICR occurs when the resulting Ca2+ influx activates ryanodine receptors on the SR membrane, which causes more Ca2+ to be released into the cytosol.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 182
Incorrect
-
Question 183
Incorrect
-
Which of the following conditions has no effect on cardiac output?
Your Answer: Pregnancy
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 184
Incorrect
-
Impulse conduction through the AV node is slow and depends on the action potential produced by which of the following.
Your Answer: Sodium diffusion
Correct Answer: Calcium flux
Explanation:The action potentials in the SA and AV nodes are largely due to Ca2+, with no contribution by Na+ influx.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 185
Incorrect
-
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
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 186
Correct
-
Question 187
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).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 188
Incorrect
-
The following are examples of the functions of the vascular endothelium except:
Your Answer: Vasomotor control
Correct Answer: Tumour suppression
Explanation:Vascular endothelium has many important functions including regulation of vascular tone, molecular exchange between blood and tissue compartments, hemostasis and signaling for the immune regulation and inflammation. Depending on specific tissue needs and local stresses, endothelial cells are capable of evoking either antithrombotic or prothrombotic events. Tumor suppression is related to genes, or anti-oncogenes, that regulate a cell during cell division and replication.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 189
Correct
-
The branche(s) of the left coronary artery include:
Your Answer: Left circumflex artery & anterior interventricular artery
Explanation:The left main coronary divides into branches:
1. The left anterior descending artery branches off the left coronary artery and supplies blood to the front of the left side of the heart.
2. The circumflex artery branches off the left coronary artery and encircles the heart muscle.
The anterior interventricular artery is otherwise known as the anterior descending branch. The posterior descending artery comes from Right coronary artery.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 190
Incorrect
-
In Jugular vein pressure the “a” wave represents?
Your Answer: None of above
Correct Answer: Atrial systole
Explanation:The jugular venous pressure (JVP, sometimes referred to as jugular venous pulse) is the indirectly observed pressure over the venous system via visualization of the internal jugular vein. It can be useful in the differentiation of different forms of heart and lung disease. Classically three upward deflections and two downward deflections have been described: The upward deflections are the a (atrial contraction), c (ventricular contraction and resulting bulging of tricuspid into the right atrium during isovolumetric systole) and v = venous filling.The downward deflections of the wave are the x (the atrium relaxes and the tricuspid valve moves downward) and the y descent (filling of ventricle after tricuspid opening).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 191
Incorrect
-
Concerning surface anatomy, where is the aortic valve found?
Your Answer: Situated in the right third intercostal space underneath the sternum
Correct Answer: Situated in the left third intercostal space underneath the sternum
Explanation:The aortic valve is situated in the left 3rd intercostal space just beneath the sternum.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 192
Incorrect
-
The effects of β1 stimulation include the following
Your Answer: Only a and b are correct
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 193
Incorrect
-
With regards to the cardiac cycle which of the following is true
Your Answer: Left ventricular ejection begins before right ventricular ejection
Correct Answer: Right atrial systole occurs before left atrial systole: as below
Explanation:Cardiac cycle: The first event in the cycle is atrial depolarization (a P wave on the surface ECG) follows by RIGHT ATRIAL and then LEFT ATRIAL contraction. Ventricular activation (QRS) follows after a short interval (the PR interval). LEFT VENTRICULAR contraction starts shortly thereafter RIGHT VENTRICULAR contraction begins. At the end, the aortic valve closure is followed by pulmonary valve closure.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 194
Incorrect
-
Following an action potential, cytosolic Ca2+ is increased. The binding of free Ca2+ to troponin C results in all of the following except:
Your Answer: Exposure of actin binding site for myosin
Correct Answer: Weakening of the troponin i interaction with actin
Explanation:At rest, troponin i is bound to actin and tropomyosin and covers the site where the myosin head interacts with actin. When Calcium enters into the muscle, it binds with troponin C and cause a structural change in troponin i which moves out of the myosin binding site and causes the cross bridges between the actin and myosin filaments to occur.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 195
Incorrect
-
Concerning coronary arteries, what is the net effect of B2 stimulation on the heart (e.g. Running athlete)?
Your Answer: Vasoconstriction via production of metabolites
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 196
Incorrect
-
Which of the following has the shortest duration:
Your Answer: Atrial diastole
Correct Answer: Atrial systole
Explanation:Atrial systole: 0.1s
Atrial diastole: around 0.4s
Ventricular diastole: 0.4-0.53s
Ventricular systole: 0.27s
PR interval: 0.12-0.2 s
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 197
Incorrect
-
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.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 198
Correct
-
Question 199
Incorrect
-
What is the most common cardiac defect seen in patients with Down’s syndrome?
Your Answer: Ventricular septal defect
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
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 200
Incorrect
-
AV valves open during?
Your Answer: None of the above
Correct Answer: Early diastole
Explanation:The cardiac cycle refers to a complete heartbeat from its generation to the beginning of the next beat, and so includes the diastole, the systole, and the intervening pause.The first stage, diastole, is when the semilunar valves (the pulmonary valve and the aortic valve) close, the atrioventricular (AV) valves (the mitral valve and the tricuspid valve) open, and the whole heart is relaxed. The second stage, atrial systole, is when the atrium contracts, and blood flows from atrium to the ventricle.The third stage, isovolumic contraction is when the ventricles begin to contract, the AV and semilunar valves close, and there is no change in volume. The fourth stage, ventricular ejection, is when the ventricles are contracting and emptying, and the semilunar valves are open. During the fifth stage, isovolumic relaxation time, pressure decreases, no blood enters the ventricles, the ventricles stop contracting and begin to relax, and the semilunar valves close due to the pressure of blood in the aorta.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
SESSION STATS - PERFORMANCE PER SPECIALTY
