When the doctor uses a stethoscope,she can listen to your beating heart.She hears "lub-dub,lub-dub." These sounds are created by _____.

Question

Quizplus · Accepted Answer

The "lub-dub" sounds heard through a stethoscope are caused by the heart valves closing. The first sound ("lub") occurs when the mitral and tricuspid valves close at the beginning of systole, and the second sound ("dub") occurs when the aortic and pulmonary valves close at the beginning of diastole. This action prevents the backflow of blood and is not directly related to muscle contractions, blood flow through the aorta, or pressure differentials alone, but rather the effect of blood recoiling against the closed valves.

When the Doctor Uses a Stethoscope,she Can Listen to Your