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24 Cards in this Set
- Front
- Back
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What are the 4 factors that determine contractility?
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ANS input, hormones: all ultimately affect calcium influx
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Why is preload and after load different from contractility?
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Preload and afterload are related to volumes of blood moved, contractility affect hearts ability to pump volume
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WHat inotropic effect does sympathetic stimulation have on the heart?
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positive inotropic effect
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How does sympathetic innervation maintain filling times?
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By increasing the force\rate of contraction and relaxation(graphically represented as more sloped parabola)
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How does increased sympathetic stimulation affect ESV?
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Makes it smaller
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What 2 things affect ESV?
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Contractility and afterload
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What 3 things does contractility affect in the cardiac cycle and how?
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Contraction velocity, Ejection fraction\ SV, Decrease ESV
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WHat can be measured via echocardiography, what by catheterization?
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Ejection fraction, Isovolumetric pressure change rates
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What is an abnormal ejection fraction?
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<40
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What is the equation for CO?
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CO=HR x SV
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Why is CO relatively constant between 50-150 bpm?
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Because HR and SV are inversely related.
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What are 2 ways that CO is maintained at high rates using Ca?
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At high rates more calcium is pulled in per unit time and more stored in SarcR
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What are the 2 ways to calculate LVSW?
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=MAP x SV
=LVPP x SV |
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How is MAP calculated?
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=DP + 1\3 PP
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How is LVMW calculated
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=LVSW x HR
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What is the oldest method of cardiac output and how is it calculated?
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Ficks method
CO=O2 consumption (respirometer)/(aterial O2-Venous O2) |
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Why cant O2 concentration be taken in the right atrium?
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Blood not sufficiently mixed
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What are the units of Ficks method/
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L blood\min
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What percentage of heart metabolic activity goes toward basal metabolism? Contraction?
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~25%, ~75%
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How much of the hearts metabolic needs are met by carbohydrate substrates? Where does rest come from?
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35-40%
Fatty acid oxidation |
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Is cardiac muscle highly aerobic?
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yEs
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What is cardiac efficiency? NOrmal range?
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ratio of work done to metabolic consumption
about 5-15% |
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Why does efficiency go up during exercise with regard to the work done?
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MOre volume work in exercise. Volume work is less costly than pressure work
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WHat is pressure work versus volume work?
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moving volume of blood
working against afterload |
