Question

Which one of the following statements is correct?

• A. The atrioventricular node (AVN) generates an action potential to stimulate atrial contraction
• B. The tricuspid and the bicuspid valves open due to the pressure exerted by the simultaneous contraction of the atria
• C. Blood moves freely from atrium to the ventricle during joint diastole
• D. Increased ventricular pressure causes closing of the semilunar valves

Answer 1

Answer: (C)

Blood moves freely from atrium to the ventricle during joint diastole

Answer 2

The Sino-atrial node generates new action potential. With the decline of ventricular pressure, the tricuspid and bicuspid valves are pushed open by the pressure in the atria exerted by the blood which was being emptied into them by the veins. Joint diastole refers to the phase in the cardiac cycle of the heart when both atria and ventricles are relaxed. During joint diastole, blood is poured into the left and right atria. Due to this filling of blood, atrioventricular valves (Bicuspid and Tricuspid valves) open and allow blood to flow from atria to ventricles. During ventricular diastole, the ventricular pressure falls causing the closure of semilunar valves and this prevents the backflow of blood into the ventricles.