Question

define or describe first heart sounds

Answer 1

Ans: The first heart sounds or S1 heart sound is a low-frequency sound, occurring at the beginning of systole. S1 can be best heard over the apex, using a stethoscope's bell or diaphragm. The first heart sound is caused by turbulence created when the mitral and tricuspid valves close. The first heart sound (S₁) is composed of several high-frequency components; only the first two are normally audible. These two sets of audible vibrations are temporally related to the closure of the mitral and tricuspid valves.

While the first heart sound coincides with contraction of the ventricles, thus identifying the onset of ventricular systole and the end of mechanical diastole.