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What is First heart sound corresponds to: and explain in detail?
The first heart sound (S1) includes mitral and tricuspid valve closure. 

The First heart sound is associated with closure of the A-V Valves.
The Second heart sound Is associated with closure of the Aortic and Pulmonary Valves.
The Third heart sound occurs at the beginning of the middle third of diastole. Occasionally a weak, rumbling third heart sound is heard at the beginning of the middle third of diastole.  
Atrial contraction sound (Fourth heart sound). 

Reference: : Guyton and Hall Physiology page no  283,284