511. First heart sound occurs during the period of________________?

A. Isotonic relaxation
B. Isovolumetric relaxation
C. Isovolumetric contraction
D. Isotonic contraction

512. Cardiac output in L/min divided by heart rate equals_______________?

A. Cardiac efficiency
B. Cardiac index
C. Mean stroke volume
D. Mean arterial pressure

513. Under resting condition the cardiac output is _______ L/ min ?

A. 2.5
B. 4.25
C. 5.25

514. Conduction velocity is least in_______________?

A. AV node
B. SA node
C. SA node
D. Purkinje fibers

515. Absolute refractory period in heart______________?

A. Lasts till cardiac contraction
B. Longer than refractory period in skeletal muscle
C. A phase of cardiac cycle in which heart cannot be stimulated by any amount of stimulus
D. Corresponds with duration of action potential
E. All of the above

516. Increased functional demand on the heart produces increased size of the myocardium by _______________?

A. Hyperplasia
B. Hypertrophy
C. Fatty infiltration
D. Increased amounts of fibrous connective tissue

517. Peripheral resistance is maximum in_______________?

A. Aorta
B. Artery
C. Arteriole
D. Vein

518. Starling’s law of the heard________________?

A. Does not operate in the failing heart
B. Does not operate during exercise
C. Explains the increase in cardiac output that occurs when venous return is increased
D. Explains the increase in cardiac output when the sympathetic nerves supplying the heart stimulated

519. All the heart valves are open during which stage of cardiac cycle __________________?

A. Systolic ejection
B. Isovolumetric relaxation
C. Isovolumetric contraction
D. None of the above

520. Cardiac output is not affected by __________________?

A. Heart rate
B. Peripheral resistance
C. Systolic blood pressure
D. Venous return


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