2. Autonomic modulation of heart rate

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7 Terms

1
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Sympathetic and parasympathetic inputs _ intrinsic rhythm.

modulate, not replace

2
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Sympathetic stimulation

norepinephrine and epinephrine

3
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What is the pacemaker-cell effect of norepinephrine and epinephrine?

Increase inward sodium and calcium currents, which steepens the pacemaker slope and can raise average membrane potential. This causes the threshold to be reached sooner and for heart rate to increase.

4
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Parasympathetic stimualtion

acetylcholine

5
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What is the pacemaker-cell effect of acetylcholine?

Increase potassium efflux and decrease calcium influx, hyperpolarizes the cell and flattens the pacemaker slope. This leaders to the threshold being reached later and heart rate decreasing.

6
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autonomic input -> (5 things)

change in ion permeability -> change in pacemaker slope or

starting voltage -> change in time to threshold -> change in heart rate

7
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Circulating epinephrine from the _ can reinforce the _.

adrenal gland, sympathetic effect