-
Question 1
Incorrect
-
If both the noradrenergic and the cholinergic systems are blocked in the heart, the rate will be approximately:
Your Answer: 70/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 2
Incorrect
-
The initial rapid depolarization in the action potential of cardiac muscle cells is due to:
Your Answer: Opening of voltage-gated 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 3
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 4
Correct
-
The following is true of the sinus node:
Your Answer: It generates impulses automatically & at a quicker rate than other cardiac cells
Explanation:The SA node exhibits automaticity. It generates the impulses to which the heart beats. It fires at a faster speed than the rest of the nervous components of the heart i.e. the AV nodes, purkinje fibers. This is the reason when the SA node fails the heart beats to the rhythm of the AV node.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 5
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 6
Correct
-
Why does arterial blood pressure drop during pregnancy?
Your Answer: Progesterone relaxes vascular smooth muscle
Explanation:Progesterone relaxes vascular smooth muscle thus resulting In a decrease in total peripheral resistance. This accounts for the increase in the cardiac output.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 7
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 8
Correct
-
Which of the following results in the resting membrane potential of a myocyte?
Your Answer: Activation of outward K+ channels
Explanation:Phase 0 is caused by the sodium current. Voltage gated sodium channels open leading to the influx of sodium into the cardiac muscle cell. Phase 1 is the rapid transient repolarization phase which is caused by the inactivation of the voltage gated sodium channels and opening of the voltage gated potassium channels along with opening of the slow calcium channels. Phase 2 which is the plateau is caused by opening of the slow calcium channels. Phase 4 is caused by closing of the slow calcium channels and opening of the potassium channels leading to efflux of potassium leading to the establishment of the resting membrane potential.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 9
Correct
-
Question 10
Correct
-
The positive inotropic effect of digoxin is due to?
Your Answer: Inhibition of the sodium potassium ATPase in the myocardium
Explanation:Digitalis compounds are potent inhibitors of cellular Na+/K+-ATPase. This ion transport system moves sodium ions out of the cell and brings potassium ions into the cell. By inhibiting the Na+/K+-ATPase, cardiac glycosides cause the intracellular sodium concentration to increase. This then leads to an accumulation of intracellular calcium via the Na+/Ca++ exchange system. In the heart, increased intracellular calcium causes more calcium to be released by the sarcoplasmic reticulum, thereby making more calcium available to bind to troponin-C, which increases contractility (inotropy).
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 11
Incorrect
-
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: Nonsustained ventricular tachycardia (NSVT)
Correct Answer: Age
Explanation:Hypertrophic cardiomyopathy (HCM) is a disease in which a portion of the myocardium (heart muscle) is enlarged without any obvious cause, creating functional impairment of the heart. It is the leading cause of sudden death in young athletes. The major risk factors for sudden death (SD) are recent unexplained syncope unlikely to be neurocardiogenic; HCM-related SD in first-degree or other close relatives; repetitive and/or prolonged nonsustained ventricular tachycardia (NSVT) episodes on Holter or extended ambulatory monitoring; massive left ventricular hypertrophy (LVH) (wall thickness ≥30 mm); extensive/diffuse late gadolinium enhancement (LGE); end-stage heart failure usually with systolic dysfunction; and thin-walled akinetic LV apical aneurysm with regional scarring.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 12
Incorrect
-
Vasodilatation in skeletal muscle can be caused by:
Your Answer: AVP
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 13
Incorrect
-
Which of the following occurs during a Valsalva manoeuvre?
Your Answer: Disruption of autonomic function
Correct Answer: An initial rise in blood pressure
Explanation:The Valsalva maneuver involves forced expiration against a closed glottis. It has several phases, each affecting the cardiovascular system differently:
- Phase I: During the initial forced expiration against the closed glottis, there is a transient rise in intrathoracic pressure, which compresses the thoracic aorta and causes a brief increase in blood pressure.
- Phase II: Continued straining leads to decreased venous return to the heart, reducing cardiac output and causing a drop in blood pressure. This phase is characterized by a compensatory increase in heart rate.
- Phase III: Upon releasing the strain, there is a sudden drop in intrathoracic pressure, which momentarily decreases blood pressure.
- Phase IV: Blood pressure then rises rapidly as venous return to the heart is restored, leading to increased cardiac output. This is often followed by a reflex bradycardia (slow heart rate).
Given these phases, the most accurate statement about what occurs during the Valsalva maneuver is the initial rise in blood pressure (Phase I).
Other options explained:
- Forced inspiration against a closed glottis: Incorrect. The Valsalva maneuver involves forced expiration, not inspiration, against a closed glottis.
- Low intrathoracic pressures throughout: Incorrect. The Valsalva maneuver involves high intrathoracic pressures due to forced expiration.
- Disruption of autonomic function: Incorrect. The Valsalva maneuver affects autonomic function but does not disrupt it. Instead, it triggers autonomic responses to changes in blood pressure and heart rate.
- No change: Incorrect. The Valsalva maneuver causes significant changes in blood pressure and heart rate.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 14
Incorrect
-
The predominant receptors in the hearts conduction system are?
Your Answer: Α1
Correct Answer: Î’1
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 15
Correct
-
Which of the following are responsible for the 4th heart sound?
Your 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 16
Incorrect
-
Transport of Ca2+ into the reticulum to initiate cardiac muscle relaxation in via:
Your Answer: Dihydropyridine receptors
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 17
Correct
-
The right border of the heart corresponds to which line on the surface of the chest?
Your Answer: Line drawn from the 3rd right costal cartilage to the 6th right costal cartilage
Explanation:The right border corresponds to a line drawn from the 3rd right costal cartilage to the 6th right costal cartilage; this border is slightly convex to the right.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 18
Correct
-
When looking at the JVP what does the c wave signify:
Your 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 19
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 20
Incorrect
-
Xanthines (for example Caffeine), exhibit their positive inotropic effect by:
Your Answer: Stimulation of b1-adrenergic receptors
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 21
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 22
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 23
Correct
-
The amount of a substance taken up by an organ (or whole body) per unit time is = (the arterial level - the venous level) * the blood flow. This statement describes?
Your Answer: The Fick principle
Explanation:The essence of the Fick principle is that blood flow to an organ can be calculated using a marker substance if the following information is known:- Amount of marker substance taken up by the organ per unit time- Concentration of marker substance in arterial blood supplying the organ- Concentration of marker substance in venous blood leaving the organ
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 24
Correct
-
Calcium induced calcium release occurs in the sarcoplasmic reticulum by activation of which receptors
Your 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 25
Correct
-
What is a characteristic findings on ECG in hyperkalaemia?
Your Answer: Tall, tented T waves
Explanation:Hyperkalaemia leads to:
– Prolonged PR interval
– Small P waves
– Tall, tented T waves
– Widened QRS complexes and eventually asystole.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 26
Incorrect
-
Which of the following best describes the cardiac muscle?
Your Answer: Striated and voluntary
Correct Answer: Striated and involuntary
Explanation:Cardiac muscle (heart muscle) is an involuntary, striated muscle that is found in the walls and histological foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 27
Incorrect
-
Which of the following structures of the cardiac conduction system is located in the right posterior portion of the interatrial septum?
Your Answer: Internodal atrial pathways
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 28
Correct
-
Water hammer pulse is found in:
Your 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 29
Correct
-
Regarding cardiac muscle contractility, the afterload refers to:
Your Answer: The resistance against which blood is expected
Explanation:The afterload for the left ventricle is the aortic pressure. Hence it is this pressure that offers resistance against which the blood is to be expelled from the heart.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 30
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 31
Incorrect
-
Which one of the following is a cause of a soft second heart sound?
Your Answer: Mitral regurgitation
Correct Answer: Aortic stenosis
Explanation:Second heart sound (S2) forms the dub of lub-dub and is composed of components A2 and P2. •   loud: hypertension•   soft: AS•   fixed split: physiological split (normally occurs during inhalation), right bundle branch block, pulmonary stenosis, and atrial septal defect.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 32
Correct
-
Which of the following components regulate cardiac output?
Your 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 33
Incorrect
-
Which of the following makes up the thick filaments in muscle fibers?
Your Answer: Actin
Correct Answer: Myosin
Explanation:The thick filaments are made up of myosin and the thin filaments are made up of actin. The thick filaments are twice the size of the thin filaments and are aligned to form the A band. The thin filaments extending out from the A band form the less dense I bands.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 34
Incorrect
-
Cross-bridges between actin and myosin filaments contain:
Your Answer: ATPase
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 35
Incorrect
-
The approximate incidence of deep venous thrombosis (DVT) in the general population each year is:
Your Answer: 50 per 1000
Correct Answer: 1 per 1000
Explanation:About 1 in 1000 adults per year has DVT, but as of 2011, available data is dominated by North American and European populations. DVT is rare in children, with an incidence of about 1 in 100,000 a year. From childhood to old age, incidence increases by a factor of about 1000, with almost 1% of the elderly experiencing DVTs yearly.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 36
Correct
-
Question 37
Correct
-
A 27-year-old man presents with a regular tachycardia of 190 bpm. He is healthy and has no past medical history. Blood pressure and blood tests are all within normal parameters however the ECG confirms a narrow complex tachycardia. The tachycardia persists after giving IV adenosine 6mg. What should be the next step in management of this patient?
Your Answer: IV 12mg adenosine
Explanation:For narrow complex tachycardias with no compromise then vagal manoeuvres should be trialled first. The Valsalva manoeuvre should be the first vagal manoeuvre tried and works by increasing intra-thoracic pressure and affecting baroreceptors (pressure sensors) within the arch of the aorta. It is carried out by asking the patient to hold his/her breath while trying to exhale forcibly as if straining during a bowel movement. Adenosine, an ultra-short-acting AV nodal blocking agent, is indicated if vagal manoeuvres are not effective. Adenosine may be safely used during pregnancy. In adults the recommended first dose of intravenous adenosine is 6 mg. The dose is administered rapidly and then followed by a saline flush. Adenosine is only present in the circulation for about 5 seconds, so it is an excellent drug for diagnosis and treatment. If there was a response to adenosine but it was not long lasting, an additional dose of 12 mg of adenosine intravenously can be attempted. Doses greater than 12 mg are not recommended. If adenosine fails then Verapamil or a beta blocker can be used as alternatives. If the patient is hemodynamically unstable or other treatments have not been effective, synchronized electrical cardioversion may be used.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 38
Incorrect
-
The function of ATP in cardiac muscle contraction includes:
Your Answer: Cross linkage of actin and myosin
Correct Answer: Binding to myosin after the power stroke to allow uncoupling of actin and myosin
Explanation:After calcium binds to the troponin C, there is a conformational change in the structure of troponin I and tropomyosin, which moves out of the way and frees the site where myosin can bind to actin. This results in the formation of the cross linkage of the actin and myosin giving rise to the power stroke in the contraction phase. This occurs with the release of ADP. When ATP combines to this complex it breaks and the cycle repeats itself.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 39
Incorrect
-
The following contributes to the rate of depolarization?
Your Answer: Stretch
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 40
Correct
-
The Wiebel-Palade body found in the endothelial cells is responsible for the production and release of which factor?
Your Answer: Von Willebrand factor
Explanation:Weibel-Palade bodies are the storage granules of endothelial cells, the cells that form the inner lining of the blood vessels and heart. They store and release two principal molecules, von Willebrand factor and P-selectin, and thus play a dual role in haemostasis and inflammation.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 41
Correct
-
Question 42
Correct
-
Which ion channel does not contribute to the myocardial action potential?
Your Answer: Chloride channel
Explanation:The upstroke in the cardiac action potential is due to opening of the sodium channels and an influx of sodium into the cell. The initial repolarization phase is due to transient opening of the potassium channels along with calcium channels. Influx of calcium causes the prolonged plateau phase of the action potential. Delayed opening of the rectifier potassium channel and delayed closure of the calcium channel leads to the repolarization phase of cardiac action potential.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 43
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 44
Incorrect
-
Regarding the cardiac muscle striations as viewed under the microscope, which areas are dark?
Your Answer: I band and z line
Correct Answer: A band and z line
Explanation:Dark bands: a, h. Dark line: z. Clear band: i, m
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 45
Incorrect
-
Which one of the following is a risk factor for torsade de pointes?
Your Answer: Hyperkalaemia
Correct Answer: Hypothermia
Explanation:The following is a list of factors associated with an increased tendency toward torsades de pointes:- Hypokalaemia (low blood potassium)- Hypomagnesemia (low blood magnesium)- Hypocalcaemia (low blood calcium)- Bradycardia (slow heartbeat)- Heart failure- Left ventricular hypertrophy- Hypothermia- Subarachnoid haemorrhage- Hypothyroidism
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 46
Incorrect
-
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: ADP
Correct 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 47
Correct
-
What are the diagnostic criteria for an ST segment elevation type of acute myocardial infarction?
Your Answer: 1 mm ST elevation in 2 limb leads
Explanation:The current guidelines for the ECG diagnosis of the ST segment elevation type of acute myocardial infarction require at least 1 mm (0.1 mV) of ST segment elevation in the limb leads, and at least 2 mm elevation in the precordial leads. These elevations must be present in anatomically contiguous leads. (I, aVL, V5, V6 correspond to the lateral wall; V3-V4 correspond to the anterior wall ; V1-V2 correspond to the septal wall; II, III, aVF correspond to the inferior wall.)
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 48
Incorrect
-
Following an action potential, cytosolic Ca2+ is increased. The binding of free Ca2+ to troponin C results in all of the following except:
Your Answer: Formation of myosin/troponin i cross-bridges
Correct Answer: Weakening of the troponin i interaction with actin
Explanation:At rest, troponin i is bound to actin and tropomyosin and covers the site where the myosin head interacts with actin. When Calcium enters into the muscle, it binds with troponin C and cause a structural change in troponin i which moves out of the myosin binding site and causes the cross bridges between the actin and myosin filaments to occur.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 49
Incorrect
-
The process by which depolarization of the muscle fiber initiates contraction is called?
Your Answer: Activation of contraction
Correct Answer: Action potential
Explanation:This process is known as an action potential. Upon generation of an action potential when depolarization reaches threshold, it spreads throughout the muscle fiber, resulting in generation of an excitation-contraction coupling leading to contraction of the muscle.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
-
Question 50
Correct
-
Which of the following conditions has no effect on cardiac output?
Your Answer: Sleep
Explanation:Sleep has no effect on the cardiac output. Anxiety, excitement and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.
-
This question is part of the following fields:
- Cardiovascular
- Medicine
-
SESSION STATS - PERFORMANCE PER SPECIALTY
