Heart Sounds

The sounds (heard normally with the doctor’s stethoscope) which result from closure of the heart valves with each heart beat. The two atrioventricular valves (mitral valve and tricuspid valve) close at the beginning of each beat, producing the ‘first heart sound’. The two arterial valves (pulmonary valve and aortic valve) close at the end of each heart beat, producing the ‘second heart sound’.