Which one of the following statements is correct?
The atrio-ventricular node (AVN) generates an action potential to stimulate atrial contraction
The tricuspid and the bicuspid valves open due to the pressure exerted by the simultaneous contraction of the atria
Blood moves freely from atrium to the ventricle during joint diastole.
Increased ventricular pressure causes closing of the semilunar valves.
Option (3) is the correct answer because during joint diastole, blood moves freely from atrium to ventricle as atrioventricular valve remain open during joint diastole. Option (4) is incorrect because decrease in ventricular pressure, during ventricular diastole closes semilunar valves to produce 'dub' heart sound. Option (1) is incorrect because SA node generates action potential to stimulate atrial contraction. Option (2) is incorrect because bicuspid and tricuspid valves open due to pressure exerted by blood present in atria and decrease in pressure in ventricles during ventricular diastole.
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