PHYSIOLOGY
CARDIOVASCULAR PHYSIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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closing of the mitral and tricuspid valves
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closing of the pulmonary and aortic valves
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sound of blood rushing into the atria
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sound of blood rushing into the ventricles
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Detailed explanation-1: -This sound comes from the valves shutting on the blood inside the heart. The first sound (the lub) happens when the mitral and tricuspid valves close. The next sound (the dub) happens when the aortic and pulmonary valves close after the blood has been squeezed out of the heart.
Detailed explanation-2: -The “lub” sound occurs during the early phase of ventricular contraction and is produced by closing of the atrioventricular valves, which prevents blood backflow into the atria. When the ventricles relax, the blood pressure drops below what is in the arteries and the semilunar valves close, producing the “dub” sound.
Detailed explanation-3: -At this time, semilunar valves are open, and both the AV valves (bicuspid-tricuspid valves) are closed. The closing of the AV valves during the ventricular systole produces the first heart sound called “LUB".