APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -S2 is produced in part by hemodynamic events immediately following closure of the aortic and pulmonic valves . The vibrations of the second heart sound occur at the end of ventricular contraction and identify the onset of ventricular diastole and the end of mechanical systole.

Detailed explanation-2: -As the ventricles contract, ventricular pressure exceeds arterial pressure, the semilunar valves open and blood is pumped into the major arteries. However, when the ventricles relax, arterial pressure exceeds ventricular pressure and the semilunar valves snap shut.

Detailed explanation-3: -The first sound LUB is produced when the atrioventricular valves i.e. tricuspid and bicuspid valves close at the start of ventricular systole. The second sound DUB is produced at the beginning of ventricular diastole when the pulmonary and aortic semilunar valves close.