Question

Heart sounds are produced due to ______.

1. closure of tricuspid and bicuspid valves

2. rushing of blood through valves producing turbulence

3. closure of atrioventricular and semilunar valves

4. entry of blood into auricles

Answer 1

Heart sounds are produced due to closure of tricuspid and bicuspid valves and closure of atrioventricular and semilunar valves.

Explanation:

The first sound "LUBB" is produced when the atrio-ventricular (tricuspid and bicuspid) valves get closed sharply at the start of ventricular systole. The second sound "DUP" is produced when at the beginning of ventricular diastole, the semilunar valves at the roots of aorta and pulmonary artery get closed.