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8 Cards in this Set
- Front
- Back
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Preload is...
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degree of myocardial fiber stretch at end of diastole & before contraction. It's determined by amount of blood returning to heart from both the venous system(right heart) & pulmonary system(left)
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Afterload is...
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pressure or resistance that the ventricles must overcome to eject blood thru semilunar valves into peripheral blood vessels; amount of resistance directly r/t arterial BP & blood vessel diameter.
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Cardiac output (CO)...
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volume of blood pumped from LV each minute; normal range in adults is 4 to 7L/min
(CO=HR x SV) |
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Stroke volume (SV)...
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amount of blood pumped by LV during each contraction.
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Systemic vascular resistance....
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resistance to flow of blood thru blood vessels; it increases when vessels contract & decreases when they dialate.
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Variables that influence SV and, ultimately, CO?
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HR, preload, afterload & contractility.
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Contractility is increased by what factors?
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sympathetic stimulation, calcium release & positive inotropic drugs.
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Contractility is decreased by what factors?
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hypoxia and acidemia.
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