PATHOLOGY MCQ
HEART
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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opening of the pulmonary and aortic valves
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closure of the tricuspid and bicuspid valves
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closure of the pulmonary and aortic valves
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opening of the tricuspid and bicuspid valves
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Detailed explanation-1: -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.
Detailed explanation-2: -Rouanet, more than 140 years ago, attributed the second heart sound to closure of the aortic and pulmonic valves.
Detailed explanation-3: -The second heart sound (S2) represents closure of the semilunar (aortic and pulmonary) valves (point d). S2 is normally split because the aortic valve (A2) closes before the pulmonary valve (P2). The closing pressure (the diastolic arterial pressure) on the left is 80 mmHg as compared to only 10 mmHg on the right.
Detailed explanation-4: -The valves are located between the atria and ventricles, and between the ventricles and the major arteries from the heart. Normal heart sounds are called S1 and S2. They are the “lubb-dupp” sounds that are thought of as the heartbeat. These sounds are produced when the heart valves close.