Q. Doctors use stethoscope to hear the sound; produced during each cardiac cycle. The second sound is heard when :
A) AV node receives signal from SA node
B) AV valves open up
C) Ventricular walls vibrate due to gushing of blood from atria
D) Semilunar valves close down after the blood flows into vessels from ventricles
Explanation
[Solution] The second heart sound 'dub' is due to closure of the semilunar valves. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.