ANATOMY

Detailed explanation-1: -The second heart sound (S2) is a short burst of auditory vibrations of varying intensity, frequency, quality, and duration. It has two audible components, the aortic closure sound (A2) and the pulmonic closure sound (P2), which are normally split on inspiration and virtually single on expiration.

Detailed explanation-2: -Second Heart Sound (S2) The second heart sound is produced by the closure of the aortic and pulmonic valves. The sound produced by the closure of the aortic valve is termed A2, and the sound produced by the closure of the pulmonic valve is termed P2.

Detailed explanation-3: -Thus, the correct answer is ‘Semilunar valves.

Detailed explanation-4: -The heart tone “lub, ” or S1, is caused by the closure of the mitral and tricuspid atrioventricular (AV) valves at the beginning of ventricular systole.

Detailed explanation-5: -Aortic valve closure (A2) which happens first. Pulmonic valve closure (P2) which happens second. A2 is heard widely all over the chest.