: This closure prevents blood from flowing backward into the atria while the ventricles are squeezing.
: Occurs at the end of ventricular systole and the beginning of ventricular diastole (when the ventricles relax to refill with blood). heartbeat lub dub sound
The rhythmic "lub-dub" sound of a heartbeat is one of the most fundamental signs of life. While it may seem like a simple mechanical beat, it is actually a precisely timed acoustic event caused by the heart's valves snapping shut. : This closure prevents blood from flowing backward
: Prevents blood that has just been pumped into the arteries from leaking back into the heart. heartbeat lub dub sound