Lub Dub Sound Heart |best| ⚡ | Tested |

Occurs at the beginning of systole (ventricular contraction). Cause: The closure of the atrioventricular (AV) valves :

The mitral valve closes slightly before the tricuspid valve, but normally they are heard as a single sound. lub dub sound heart

Occurs at the end of systole / beginning of diastole (ventricular relaxation). Cause: The closure of the semilunar valves : Occurs at the beginning of systole (ventricular contraction)

Bilal Hasdemir * The 'lub-dub' sound of a healthy heart is more than just a beat. It's a key to understanding heart health. ... * ... Liv Hospital Heart Murmurs | The Texas Heart Institute® Heart Murmurs. ... Normal heart sounds come in pairs. The sounds are often described as a constant “lub-dub, lub-dub.” The first “... The Texas Heart Institute Heart Murmurs | The Texas Heart Institute® Normal heart sounds come in pairs. The sounds are often described as a constant “lub-dub, lub-dub.” The first “lub-dub” is the sou... The Texas Heart Institute 17.4C: Heart Sounds - Medicine LibreTexts Oct 14, 2025 — Cause: The closure of the semilunar valves :

The lub-dub sound of the heart is an important indicator of heart health. A normal heart rate is between 60-100 beats per minute, and a regular rhythm is essential for maintaining proper blood flow and overall health.

In conclusion, the "lub-dub" sound is much more than a biological heartbeat; it is the audible evidence of a high-pressure pumping system functioning with incredible precision. The "lub" guards the filling stations of the heart, while the "dub" protects the exit routes. This rhythmic cycle occurs approximately 100,000 times a day, moving roughly 2,000 gallons of blood. It is a testament to the body’s engineering that such a vital, continuous process can be summarized in two simple sounds—the timeless rhythm of life itself.