Of the four "normal" heart sounds,the initial "lubb" sound is heard when the
A)AV valves close.
B)semilunar valves close.
C)AV valves open.
D)semilunar valves open.
E)foramen ovale closes.

Question

Quizplus · Accepted Answer

The initial "lubb" sound is heard when the AV (atrioventricular) valves close. This sound is caused by the sudden cessation of blood flow from the atria to the ventricles as the valves close during ventricular systole.

Of the Four "Normal" Heart Sounds,the Initial "Lubb" Sound Is