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Cardiac Output:. And Influencing Factors. Cardiac Output. Amount of blood pumped out by each ventricle in 1 min CO = HR x SV. Cardiac Reserve. The difference between resting and maximal CO. Stroke Volume. SV = EDV – ESV EDV (volume of blood in ventricle after diastole)
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Cardiac Output: And Influencing Factors
Cardiac Output • Amount of blood pumped out by each ventricle in 1 min • CO = HR x SV
Cardiac Reserve • The difference between resting and maximal CO
Stroke Volume • SV = EDV – ESV • EDV (volume of blood in ventricle after diastole) • ESV (volume of blood remaining in ventricle after contraction) • With each beat, ~ 60% of blood in chambers is emptied
Frank-Starling law of the heart • Preload = critical factor in determining SV
Preload • Degree to which cardiac cells are stretched before contraction • Optimal length determined by: • If max # of cross bridge attachments occur • If max force of contraction occurs
Venous Return • The volume of blood returning to heart and stretching ventricles • If venous return increases, EDV increases; therefore SV increases • Left and right ventricles have equal venous return; therefore blood does not “pool” or backflow in heart
Contractility • Contractile strength of heart (due to increased CA2+) • Causes increased release of blood (therefore lower ESV)
Afterload • Force to eject blood from ventricles • Constant in healthy people; lower in people with hypertension (therefore increases ESV and decreases SV)