Question
Doctors use stethoscope to hear the sounds produced during each cardiac cycle. The second sound is heard when
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AB valves open up
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Ventricular walls vibrate due to gushing in of blood from atria
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Semilunar valves close down after the blood flows into vessels from ventricles
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AV node receives signal from SA node
Solution
C.
Semilunar valves close down after the blood flows into vessels from ventricles
In healthy adults, there are two normal heart sounds often described as lubb and dup. These are the first heart sound and second heart sound produced by closing of the AV valves and semilunar valves respectively.
