S1 And S1: Heart Sounds

It is caused by the near-simultaneous closure of the atrioventricular (AV) valves : the mitral and tricuspid valves. This closure prevents blood from leaking back into the atria as the ventricles squeeze.

Contrary to popular belief, S1 is not the sound of the heart "beating" or contracting. Instead, it is generated by the and the subsequent vibration of cardiac structures immediately following the closure of the atrioventricular (AV) valves. s1 and s1 heart sounds

The First Heart Sound - Clinical Methods - NCBI Bookshelf - NIH It is caused by the near-simultaneous closure of

As the ventricles contract during systole, ventricular pressure rises sharply above atrial pressure. This pressure gradient forces the mitral and tricuspid valves to snap shut, preventing blood from flowing backward (regurgitation) into the atria. The sudden tensing of the valve leaflets and the surrounding chordae tendineae creates audible vibrations—this is S1. Instead, it is generated by the and the