Summer Lecture Circulation 1 final

During ventricular ejection each ventricle will eject

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Unformatted text preview: he pressure in the ventricles rise above those in the atria, the AV valves snaps shut. • In the early phase of ventricular systole there is no blood flow, because ventricular pressures are not high enough to force open the semilunar valves and push blood into the pulmonary or aortic trunk. • During this period, the ventricles contract isometrically: They generate tension and ventricular pressures rise, but blood flow does not occur. Friday, July 20, 12 Ventricular Systole #2 AV = atrioventricular When the pressure in the ventricles exceeds that in the arterial trunks, the semilunar valves open and blood flows into the pulmonary and aortic trunks. This point marks the beginning of the period of ventricular ejection. During ventricular ejection, each ventricle will eject 70–80 ml of blood, the stroke volume (SV) of the heart. The stroke volume at rest is roughly 60 percent of the end–diastolic volume. This percentage, known as the ejection fraction , can vary in response to changing...
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