PHYSIOLOGY
CARDIOVASCULAR PHYSIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Flow of blood
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Closing of valves
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Opening of valves
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Breathing
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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: -Heart Sounds The first heart sound (S1) represents closure of the atrioventricular (mitral and tricuspid) valves as the ventricular pressures exceed atrial pressures at the beginning of systole (point a). S1 is normally a single sound because mitral and tricuspid valve closure occurs almost simultaneously.
Detailed explanation-3: -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.