@anonymously.m3too: The familiar "lub-dub" sound of a heartbeat is primarily produced by the rhythmic closure of the heart's valves, rather than the contraction of the heart muscle itself. The first sound, known as S1 or "Lub," occurs when the atrioventricular valves, specifically the mitral and tricuspid valves, close at the onset of ventricular contraction (systole), preventing backflow into the atria. The second sound, referred to as S2 or "Dub," is a sharper noise generated by the closure of the semilunar valves—the aortic and pulmonary valves—at the conclusion of ventricular contraction, which stops blood from returning to the heart from the major arteries. These valves act as one-way doors, ensuring unidirectional blood flow through the circulatory system, and their closure is driven by pressure changes within the heart chambers. If a valve fails to close properly, it can lead to turbulent blood flow, potentially resulting in a heart murmur detectable by a stethoscope. #heart #heartbeat #bloodflow #valves #artery

AnonymouslyM3Too

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Saturday 07 February 2026 22:08:17 GMT