Term
| SA node/Pacemaker action potential |
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Definition
rising resting potential: Na+[f] open (-60)
prethreshold: T-type Ca+ open
threshold: L-type Ca+ open
peak: K+ open
(-60): K+ close and Na+[f] open back up |
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Term
| Ventricular myocyte action potential |
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Definition
flat resting potential: K+ open
depolarization: Na+ open (sharp increase)
peak: transient K+ open
repolarization: slow closing L-type Ca+ then K+ open back up |
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Term
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Definition
I - Na+ channel blockers**
II - beta blockers
III - K+ channel blockers**
IV - Ca+ channel blockers |
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Term
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Definition
class - IA Na+ channel blocker
MOA - moderate slowing of depolarization, prolonged repolarization
Increases: duration
Decreases: velocity, excitability
AE - Lupus-like syndrome, hypotension |
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Term
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Definition
class - IB Na+ channel blocker
MOA - mild slowing of depolarization, shortened repolarization
Decreases: velocity, duration, excitability
AE - CNS effects, hypotension |
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Term
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Definition
class - IC Na+ channel blocker
MOA - severe slowing of depolarization, no change in repolarization
*blocks some K+ channels as well
*lipophillic and so has biggest effect
Decreases: velocity
AE - may exacerbate arrhythmia |
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Term
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Definition
class - K+ channel blocker
MOA - prolongs phase 3 of the cardiac action potential and also weakly blocks Na, Ca, and alpha/beta
Increases: duration, vasodilation
Decreases: velocity, heart rate
AE - hypotension, bradycardia, thyroid effects |
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Term
digoxin
(Lanoxin)(digitalis) |
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Definition
class - cardiac glycoside
MOA - inhibits Na-K-ATPase causing Ca++ influx
Increases: cardiac contractility, duration
Decreases: heart rate, velocity
AE - preventricular contractions, blurred/yellow vision |
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