EVERYDAY SCIENCE

Detailed explanation-1: -Normal heart sounds come in pairs. The sounds are often described as a constant “lub-dub, lub-dub.” The first “lub-dub” is the sound of the mitral and tricuspid valves closing. The second “lub-dub” is the sound of the aortic and pulmonary valves closing soon after.

Detailed explanation-2: -(a) First heart sound lub is produced due to closure of atrioventricular valves.

Detailed explanation-3: -When the two atrium chambers contract, the tricuspid and mitral valves open, which both allow blood to move to the ventricles. When the two ventricle chambers contract, they force the tricuspid and mitral valves to close as the pulmonary and aortic valves open.

Detailed explanation-4: -Due to the closure of the atrio-ventricular valves, dup sound is produced.

Detailed explanation-5: -The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves whereas the second heart sound (dub) is associated with the closure of the semilunar valves.