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15 Cards in this Set

  • Front
  • Back
How does the heart provide for circulatory blood flow and maintain bp?
By delivering the necessary CO
How is CO regulated?
Heart rate - pacemaker cells
Strok Vol - Starlings
adrenal medulla
secretes epinephrine from vagus

acts as NE does
Autonomic Regulation of the Heart
Area symp para
SA inc HR dec HR
AV inc cond dec cond
atrialm inc cont dec contr
ventm inc cont dec cont
effect on

intrinsic rate of SA node
remove symp and para input
Muscarinic blocker
Blocks Parasympathetics
Inhibits AcH
Increases HR
Beta adrenergic blocker
Blocks sympathetic
decreases HR
Slope and Effect of autonomic system
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
How do you increase HR?
1. Increase plasma epinenphrine
2. Increase activity of sympathetic nerves B1 receptors (NE)
3. Decrease Para activity (muscarinic)
Regulation of Stroke Volume
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
Sympathetic input and contractility
1. Sympathetic stimualtion creates a new upward shifted Starling curve of increased contractility
2. This increases ejection fraction
3. This increases stroke volume
Positive Inotropic Effect
Negative Inotropic Effect
Increased contractility
decreased Contractility
Physiology of Sympathetic Input on Contraction
1. increases Ca influx
2. increases strength of contraction
3. increases rate of Ca remova from cytoplasm
4. strengthens and shortens the contractile twitch
How do you increase SV?
1. Increase EDV
2. Activate Sympathetic
3. Increase plasma epinephrine
Regulation Of CO
cardiac muscle HR
inc epi inc epi
sympa sympa
inc EDV Dec para