Question

The first heart sound 'lubb?
(1) marks the beginning of ventricular systole
(2) marks the end of ventricular systole
(3) is due to closure of atrioventricular valves
(4) is produced by the closure of semilunar valves

• A. 1, 2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (D)

Each heart beat is accompanied by two heart sounds. The first heart sound of 'lubb' marks the beginning of ventricular systole and is due to closure of atrioventricular valves. The second heart sound of 'dupp' marks the end of ventricular systole and beginning of its diastole. It is produced by the closure of semilunar valves.