Quiz: Physiology

Regarding the right coronary artery, one statement is wrong

A Arises from anterior aortic sinus. B Usually supplies sinoatrial node. C Gives anterior interventricular artery. D Gives posterior interventricular artery.

Which of the following is the shortest event in a cardiac cycle?

A ORS interval B ST segment C ST interval D RR interval

Stimulation of sympathetic nerves to the heart decreases

A Heart rate B Force of cardiac contraction C Heart conductivity D Refractory period

During the cardiac cycle, aortic valve closes at the end of

A Isovolumetric systole B Rapid ejection C Reduced ejection D Protodiastole

The best measure of left ventricular preload is

A Left ventricular end-diastolic volume B left atrial pressure C right atrial pressure D central venous pressure

During severe exercise, a well-trained athlete may be able to achieve a cardiac output of

A 10 liters B 15 liters C 25 liters D 35 liters

The mechanism that regulates cerebral blood flow during cerebral compression is the

A Baroreceptor reflex B Bezold-Jarisch reflex C Bainbridge reflex D Cushing's reflex

In ECG the depolarization of atria is indicated by

A T wave B P wave C Q wave D R wave

The Bainbridge reflex refers to

A The central venous pressure reflex B The carotid-sinus reflex C The aortic baroreceptors reflex D The chemoreceptor reflex

Cardiac output is determined by

A a) heart rate alone B b) stroke volume and ABP C c) blood flow D d) heart rate and stroke volume

An electrocardiogram is a graphic illustration of

A a) cardiac conduction system B b) cardiac cycle C c) cardiac output D d) ABP

These factors decrease the coronary blood flow EXCEPT

A a) Angiotensin II B b) Adrenaline C c) Noradrenaline D d) Prostaglandins

Pulmonary circulation differs from systemic circulation

A a. Pulmonary vasodilation in hypoxia B b. Pulmonary arteries Carry oxygenated blood C c. Pulmonary vasoconstriction in hypoxia D d. Decreased blood volume during systole

Starling's law of the heart states that the strength of contraction is proportional to

A a) Myocardial oxygen supply B b) Stroke volume C c) The end diastolic volume. D d) Arterial blood pressure.

All of the following parameters are increased during moderate exercise EXCEPT

A a) Arteriovenous difference for O2 B b) Heart rate C c) cardiac output D d) Total peripheral resistance (T.P.R

Conduction speed is slowest in the

A a) SA node B b) atrial pathways C c) bundle of His D d) Purkinje system

Normally, which of the following events in the cardiac cycle occurs at some point between S1 and the following S2?

A a) Onset of ventricular diastole B b) Atrial systole C c) Rapid ventricular filling D d) The 'a' wave of the JVP

The most appropriate index of left ventricular afterload is

A a) systolic arterial pressure B b) mean arterial pressure C c) systemic vascular resistance D d) left ventricular systolic pressure

All of the following are physiological factors affecting blood pressure except

A a) Sleep B b) Exercise C c) Emotions D d) Atherosclerosis

Blood pressure increases and heart rate decreases in response to

A a) Exercise B b) Increased body temperature C c) Exposure to high altitude D d) Increased intracranial pressure

In the heart, parasympathetic stimulation causes all of the following effects EXCЕРТ

A a) Decreased rate of discharge from the S.A.N. B b) Coronary V.C. C c) Increased ventricular contractility. D d) Increase HR

These factors increase the coronary blood flow EXCEPT

A a) Local hypoxia B b) Increased extracellular K+ level C c) Vasopressin D d) Adenosine

All these statements are true about cardiac output EXCEPT

A a) Is normally expressed as the output of one ventricle in litres/minute. B b) May not increase when heart rate rises. C c) Usually rises when a person lies down. D d) Does not increase in exercise following denervation of the heart.

The cardiac reserve refers to the increase than can be attained in the

A a) Cardiac work B b) Cardiac output C c) Stroke volume D d) All of the above

The maximal coronary blood flow occurs during the

A a) Early part of systole B b) Late part of systole. C c) Early part of diastole. D d) End of diastole.

Central venous pressure (CVP)

A a) It is the pressure in large veins just outside the right atrium B b) It is not changed during the cardiac cycle C c) It averages 20-30 mmHg in recumbancy and 40 mmHg on standing D d) It is unchanged in hypervolemia

The phase of cardiac cycle at which the heart is not responsive

A a) Is the absolute refractory period. B b) Is the relative refractory period. C c) Supernormal phase D d) Is shorter than that in the skeletal muscle.

Increased pressure within the carotid sinus causes

A a. An increase in heart rate B b. Increase COP C c. Reflex bradycardia D d. Reflex increase in venous pressure

Normally, the largest part of the blood volume is found in

A a. Veins B b. Arteries. C c. Capillaries. D d. Heart chambers

With respect to the human heart

A a. The spread of excitation through the wall of the ventricle during depolarization starts from epicardium to endocardium B b. Vagal stimulation decreases the force of ventricular contraction C c. In exercise, systole shortens more than diastole D d. In the resting subject, denervation of the heart would result in a rise in heart rate.

Regarding initiation and propagation of cardiac impulse, all are true EXCEPT

A a. The action potentials in the heart are about 100 times longer than those of skeletal muscle B b. The cells of the SA-node have a steady resting potential of -90 mV C c. The spread of cardiac excitation is delayed by about 0.15 at AVN D d. The conducting tissue of the heart is composed of specialized cardiac myocytes linked by gap junction

Venoconstriction

A a. Decreases compliance of vein walls B b. Increases compliance of vein walls C c. Increases total peripheral resistance D d. All of the above are true

Regarding the functional structure and arrangement of the cardiovascular system,all are true EXCEPT

A a. The elastic arteries act as Windkessel vessels B b. Muscular arteries offer high resistance to blood flow C c. Left ventricle pumps blood to tissues in parallel D d. Left ventricle constitutes part of the low pressure system

Contractile response of cardiac muscle

A a. Obeys the all or none law B b. Starts at the same time of electric excitation C c. Is triggered by the release of Ca+2 from SR as in skeletal muscle D d. Last for the same time as its action potential

Regarding veins, all are true EXCEPT

A a. About two-thirds of all the blood in the body is found in the systemic veins person is walking B b. The pressure in the veins of the foot will be lower when a than it will be when he is standing still C c. Sub atmospheric pressures are never found in blood vessels outside the thoracic cavity D d. They are conduits to carry blood from tissues to the right atrium

Regarding the transmission of the cardiac impulse through the heart

A a. Purkinje system having the slowest propagation velocity B b. Repolarization of atrium is represented by T-wave C c. Atrial endocardium depolarizes before epicardium D d. Ventricular endocardium repolarizes before epicardium

The slowest conduction velocity is in the

A a. Purkinje fibers B b. A-N region of AV-node C c. N-Zone of AV-node D d. N-H region of AV-node

A decrease in AV-node conduction velocity will

A a. Increase P-wave amplitude B b. Increase P-R interval C c. Widen the QRS complex D d. Increases S-T segment duration

Characteristic features of cardiac muscle fibers are all of the following EXCEPT

A a. They act as a functional syncytium B b. They are rich in mitochondria C c. They have a right junctions called intercalated discs D d. T-tubules are located at A-I junctions

Cardiac muscle cannot be tetanized because

A a. The action potential travel too slowly along the conducting tissue to stimulate the muscle B b. Contraction is possible only when the heart is filled with blood C c. The autonomic nervous system blocks rapid action potential D d. The long absolute refractory period prevented the muscle from becoming re-stimulated while still contracting.

The Frank-Starling law of the heart shows a direct relationship between stroke volume and

A a. End-systolic volume B b. End-diastolic volume C c. Mean arterial pressure D d. Cardiac output

Contractile response of cardiac muscle

A a. Starts at the same time of electric excitation B b. Is triggered by the ionic calcium from S-R as in the skeletal muscle C c. Reaches its peak tension during the last third of the plateau of A.P D d. Lasts for the same time as its action potential and not obey the all or none rule

Regarding myocardial contraction

A a. Is stronger when inward Ca+2 current is increased B b. Has higher velocity when suddenly after loaded C c. Is weaker is the beat next to an extrasystole D d. Is enhanced in systolic dysfunction

Concerning myocardial contractility, all are true EXCEPT

A a. Is dependent of preload. B b. Is homeometric and not heterometric C c. Is increased when heart rate increases D d. Can be measured by stroke volume

An increase in contractility is demonstrated in is demonstrated in a Frank Starling relationship

A a. Increased cardiac output for a given end diastolic volume B b. Increased cardiac output for a given end systolic volume. C c. Decreased cardiac output for a given end diastolic volume. D d. Decreased cardiac output for a given end systolic volume

Regarding cardiac contraction

A a. Has higher velocity when suddenly after loaded B b. Is weaker in the beat next to an extrasystole C c. Is enhanced in systolic dysfunction. D d. Is stronger when inward Ca++ current increased.

Starling law of the heart

A a. Does to opiate in the failing heart B b. Does not opiate when the heart has been denervated for transplanted C c. Does not equalizes the COP of both ventricles when changed D d. It affects the end diastolic volume of the ventricles through preload mechanism

Regarding sympathetic stimulation of the heart, all are true EXCEPT

A a. It has a positive intotropic action B b . Results in relative prolongation of the systole C c. Is mediated by increased influx of ECF ionic calcium D d. Decreases the velocity of relaxation

Stimulating the parasympathetic nerves to the heart results in

A a. An increased heart rate B b. A decreased permeability of the SA-node to K+ C c. A diminished conduction velocity through the A-V node D d. Vasoconstriction of the coronary vessels

Sympathetic stimulation of the heart causes all EXCEPT

A a. Increases the rate of the SA-node. B b. Increases force of myocardial contraction and increases the duration of the plateau of ventricular action potentia C c. Decreases the conduction time in the AV-node. D d. Increases permeability of SA-node to K+ ions

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