Heartbeat Lub Dub [better] · Genuine

, occurs when the —the aortic and pulmonary valves—close.

The "lub-dub" sound of a heartbeat is the sound of your heart valves closing to control blood flow. Each heartbeat consists of two distinct sounds that represent different parts of the cardiac cycle: The "Lub" (First Heart Sound) : This sound, known as heartbeat lub dub

: These valves control blood flow from the heart's upper chambers (atria) to the lower chambers (ventricles). Their closure prevents blood from flowing backward when the ventricles contract to pump blood out to the body. The "Dub" (Second Heart Sound) Cause : This sound, known as , occurs when the —the aortic and pulmonary valves—close