Valvular Heart Disease - developinganaesthesia

Name the normal sounds of the heart and indicate what causes these sounds. S1 is the first heart sound or "lub" and occurs due to closure of the atrioventricular (tricuspid and bicuspid) valves. S2 is the second heart sound or "dup" and occurs due to closure of the pulmonary and aortic (semilunar) valves. ................
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