NEET BIOLOGY

Detailed explanation-1: -The second sound results from vibrations set up in the pulmonary artery walls, the aorta, and the ventricles, as the blood rebounds back and forth between the walls of arteries and the valves after the closure of pulmonary and semi-aortic valves.

Detailed explanation-2: -During each cardiac cycle two prominent sounds are produced which can be heard by stethoscope. The first heart sound (lub) is associated with the closure of bicuspid and tricuspid valves while the second heart sound (dub) is associated with a closure of the semilunar valves.

Detailed explanation-3: -The most tenable to date suggests that closure of the aortic and pulmonic valves initiates the series of events that produces the second heart sound. The main audible components, however, result from vibrations of the cardiac structures after valve closure.

Detailed explanation-4: -What is a stethoscope? The stethoscope is a device that helps physicians or healthcare providers primarily to listen to the sounds generated internally by your heart, lungs and intestinal tract. It is also used to check blood pressure.

Detailed explanation-5: -The first sound (lub) is associated with the closure of the tricuspid and bicuspid valves during ventricular systole to prevent the backflow of blood to atria. The second sound (dub) is associated with the closure of semilunar valves during ventricular diastole to prevent the backflow of blood to ventricles.