During the ejection phase, left ventricular volume falls rapidly (Figure 1.03). Although pressure in the ventricle falls below aortic pressure in the second half of the phase, ejection continues, indicating that pressure is not the only form of fluid energy responsible for blood flow.
Kinetic energy which contributes heavily to total fluid energy due to the high blood flow velocity, acts to keep the valve open during late ejection. Only when total fluid energy in the ventricle falls below that in the aorta does the aortic valve close.
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