NURSING EXAM QUESTIONS
PATHOLOGY AND GENETICS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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AV valves
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Semilunar valves
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Either A or B
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None of the above
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Detailed explanation-1: -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-2: -Blood flows from the veins to the atria while the atrioventricular valves are closed. The atrial pressure increases to produce the v wave in the venous pulse (fig. 3.2). The decrease in the arterial pressure is interrupted by the dicrotic notch that is seen in the aortic pulse.
Detailed explanation-3: -Isovolumetric relaxation (d-e): When the ventricular pressures drop below the diastolic aortic and pulmonary pressures (80 mmHg and 10 mmHg respectively), the aortic and pulmonary valves close producing the second heart sound (point d). This marks the beginning of diastole.