HUMAN PHYSIOLOGY
BODY FLUIDS AND CIRCULATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Lubb sound at the end of systole
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Lubb sound at the beginning of ventrical systole
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Dup sound at the end of systole
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Dup sound at the beginning of ventrical systole
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Detailed explanation-1: -The first heart sound, called S1, makes a “lub” sound caused by the closure of the mitral and tricuspid valves as ventricular systole begins. There is a very slight split between the closure of the mitral and tricuspid valves, but it is not long enough to create multiple sounds.
Detailed explanation-2: -The first heart sound coincides with contraction of the ventricles, thus identifying the onset of ventricular systole and the end of mechanical diastole.
Detailed explanation-3: -The ejection systolic sounds are heard during the early part of ventricular systole. These sounds are generally high pitched and best audible with the diaphragm of the stethoscope. They can be valvular or vascular in origin.
Detailed explanation-4: -Normally, two distinct sounds are heard through the stethoscope: a low, slightly prolonged “lub” (first sound) occurring at the beginning of ventricular contraction, or systole, and produced by closure of the mitral and tricuspid valves, and a sharper, higher-pitched “dup” (second sound), caused…
Detailed explanation-5: -The first sound LUB is produced when the atrioventricular valves i.e. tricuspid and bicuspid valves close at the start of ventricular systole. The second sound DUB is produced at the beginning of ventricular diastole when the pulmonary and aortic semilunar valves close.