The "lub-dub" sound of a heartbeat is the sound of your heart valves closing as they direct blood flow through the heart's chambers. These sounds, known medically as S1 and S2, mark the two main phases of the cardiac cycle: systole and diastole. Licensed by Google The "Lub" (S1)
Doctors use a stethoscope to listen to these sounds (a process called cardiac auscultation ) because they provide a window into your cardiovascular health. nhlbi, nih (.gov)https://www.nhlbi.nih.gov How the Heart Works - How the Heart Beats | NHLBI, NIH what is the lub dub sound in your heart
The second sound, "dub," is shorter and slightly higher in pitch. It happens at the end of the contraction phase when the heart begins to relax. As the pressure in the ventricles drops, the —the aortic and pulmonary valves—snap shut to prevent blood from leaking back into the heart from the main arteries. Why It Matters The "lub-dub" sound of a heartbeat is the