Review Note
Last Update: 01/29/2025 02:35 PM
Current Deck: PHYSIOLOGY::exam one
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Commit #272769
What is the effect on increased aortic pressure (afterload)? On end-systolic volume?
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Commit #272769Basic answer: To open the aortic valve and eject blood, left ventricular pressure increases to higher than normal
Afterload is the pressure against which the
ventricles must eject blood- so afterload of the left ventricle is aortic
pressure. To open the aortic valve and
eject blood, left ventricular pressure must increase to a level greater than
aortic pressure. Thus, if afterload
increases, the left ventricle must work harder to overcome the higher
pressure. In the figure, during
isovolumic contraction (1-2) and ventricular ejection (2-3), ventricular
pressure increases to higher than normal.
Because of the increased afterload, stroke volume is compromised, more
blood remains in the left ventricle after ejection, and end-systolic volume is
increased. Because
stroke volume decreases and end-diastolic volume is unchanged, ejection
fraction must have decreased.
