Question

When are the sounds ‘LUBB’ and ‘DUB’ produced during heartbeat ?

Answer 1

The first sound ‘LUBB’ is produced when the atrioventricular valves get closed sharply at the start of ventricular systole. The second sound ‘DUB’ is produced at the beginning of ventricular diastole when the semilunar valves, at the roots of aorta and pulmonary artery get closed.