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...
View Full Document
- Spring '13