Explain heart sounds.

(N/A) Heart sounds are noises generated by the closing and opening of the heart valves.
In a healthy individual,there are two normal heart sounds called $lub$ and $dub$.
$Lub$ is the first heart sound. It is associated with the closure of the tricuspid and bicuspid valves at the beginning of systole.
The second heart sound $dub$ is associated with the closure of the semilunar valves at the beginning of diastole.
These sounds provide important information about the condition and working of the heart.