PATHOLOGY

Detailed explanation-1: -The second heart sound (S2) represents closure of the semilunar (aortic and pulmonary) valves (point d). S2 is normally split because the aortic valve (A2) closes before the pulmonary valve (P2).

Detailed explanation-2: -It is caused by the closure of the atrioventricular valves, i.e. tricuspid and mitral (bicuspid), at the beginning of ventricular contraction, or systole.

Detailed explanation-3: -As your heart pumps blood, four valves open and close to make sure blood flows in the correct direction. As they open and close, they make two sounds that create the sound of a heartbeat. The four valves are the aortic valve, mitral valve, pulmonary valve and tricuspid valve.