Doctors use a stethoscope to hear the sounds produced during each cardiac cycle. The second sound is heard when:
AV valves open up
Ventricular walls vibrate due to the gushing of blood from the atria
Semi-lunar valves close down after the blood flows into vessels from the ventricles
AV node receives a signal from SA node
During each cardiac cycle, two prominent sounds are produced which can be heard through a stethoscope. The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves. The second heart sound (dub) is associated with the closure of the semilunar valves, which occurs when the ventricles relax (ventricular diastole) preventing backflow from the vessels , .
Join thousands of students and practice with AI-generated mock tests.