Heart Sound Cause A. First Heart Sound (S1) 1. Rapid filling of ventricles B. Second Heart Sound (S2) 2. Closure of tricuspid and mitral valves C. Third Heart Sound (S3) 3. Atrial contraction D. Fourth Heart Sound (S4) 4. Closure of aortic and pulmonary valves

Step-by-step solution

First Heart Sound (S1) is caused by the closure of the tricuspid and mitral valves, marking the beginning of systole. Second Heart Sound (S2) occurs due to the closure of the aortic and pulmonary valves, indicating the end of systole and the start of diastole. Third Heart Sound (S3) is produced by the rapid filling of ventricles during early diastole, often associated with heart failure or high cardiac output. Fourth Heart Sound (S4) results from atrial contraction just before the S1 sound, indicating increased res