What causes the lub-dub sound of your heartbeat?

Answer 1

The 'lub' is the S1 sound. It occurs due to normal closure of the mitral and tricuspid (atrioventricular) valves. With these valves closed, systole commences and blood is actively squeezed from the ventricles. The second sound is the 'dub' or S2 sound. It occurs as the aortic (to LV) and pulmonary (to RV) valves close to prevent backflow from the blood ejected from the ventricles and marks the beginning of diastole (or filling) of the heart.

Answer 2

Heart sounds are described by the syllables "lub" and "dub." The sequence is lub-dub, pause, lub-dub, pause, and so on. The first sound (lub) is caused by the closing of the AV valves, and the second sound, (dub) is caused by the closing of the semilunar valves at the end of a systole.

The first sound (lub) is louder and longer and the second (dub) is short and sharp.

Answer 3

The Dub sound occurs when the semi-lunar valves close.