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15 Cards in this Set
- Front
- Back
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How does the heart provide for circulatory blood flow and maintain bp?
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By delivering the necessary CO
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How is CO regulated?
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Heart rate - pacemaker cells
Strok Vol - Starlings contractility |
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adrenal medulla
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secretes epinephrine from vagus
acts as NE does |
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Autonomic Regulation of the Heart
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Area symp para
SA inc HR dec HR AV inc cond dec cond atrialm inc cont dec contr ventm inc cont dec cont little effect on contracti pacemakers |
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intrinsic rate of SA node
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remove symp and para input
~100 |
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Atropine
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Muscarinic blocker
Blocks Parasympathetics Inhibits AcH Increases HR |
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Propranolol
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Beta adrenergic blocker
Blocks sympathetic decreases HR |
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Slope and Effect of autonomic system
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1. Sympathetics increase slope and HR
2. Parasympathetics decrease slope and HR To decrease slope: 1. hyperpolarize w/ paraympethetics via K channel 2. Decrease sympathetic input To increase slope: 1. Open depolarizing channels w/ sympathetic input leads to faster AP |
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How do you increase HR?
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1. Increase plasma epinenphrine
2. Increase activity of sympathetic nerves B1 receptors (NE) 3. Decrease Para activity (muscarinic) |
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Regulation of Stroke Volume
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1. Increase end diastolic volume which lengthens the cardiac muscle and allows for maximal contraction due to length/tension relationship (Starling's Law)
VERY important b/c if you give heart more blood it WILL pump it; prevents pooling Allows matching cardiac output b/w left and right |
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Sympathetic input and contractility
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1. Sympathetic stimualtion creates a new upward shifted Starling curve of increased contractility
2. This increases ejection fraction 3. This increases stroke volume |
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Positive Inotropic Effect
Negative Inotropic Effect |
Increased contractility
decreased Contractility |
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Physiology of Sympathetic Input on Contraction
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1. increases Ca influx
2. increases strength of contraction 3. increases rate of Ca remova from cytoplasm 4. strengthens and shortens the contractile twitch |
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How do you increase SV?
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1. Increase EDV
2. Activate Sympathetic 3. Increase plasma epinephrine |
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Regulation Of CO
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cardiac muscle HR
inc epi inc epi sympa sympa inc EDV Dec para |
