(D) The first heart sound,known as $LUBB$,is produced by the sudden closure of the atrioventricular $(A.V.)$ valves (tricuspid and bicuspid valves).Th

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Sudden closure of $A.V.$ valves

(D) The first heart sound,known as $LUBB$,is produced by the sudden closure of the atrioventricular $(A.V.)$ valves (tricuspid and bicuspid valves).This closure occurs at the beginning of ventricular systole due to a sharp rise in intraventricular pressure,which prevents the backflow of blood into the atria.