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22 Cards in this Set
- Front
- Back
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function of :
sodium leak channel |
resting membrane potential
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function of :
voltage-activated sodium channel |
upswing of AP
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function of :
leak K channel |
RMP
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function of :
A-type rapid inactivating K channel |
rapid repol
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function of :
T type Ca channel |
pacemaker potential
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function of :
L type Ca channel |
long lasting
plateau potential |
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function of :
H type non selective cation |
pacemaker potential
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sodium/K pump
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RMP
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examples of types of channelopathies
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Na+ fails to turn off inc depol
K+ fail to turn on dec repol |
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epicardium vs endocardium
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epi have more K+ A type fast inactivating channels
lack of O2 causes A type to become hyperactivate therefore inc in hyperpolarization back to RMP |
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HR modulation in SA node
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1. slow activation of T-type Ca+ pacemaker currents
2. change threshold potential 3. activate G-Pr coupled K+ channels (hyperpolarize the cell) (using M agonists) |
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phase 0 of ventricle
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fast Na+ activated channel
T-type Ca+ upswing of AP/rapid depol |
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phase 4 of ventricle
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K+ inward leak
Na+ leak Na+/K+ pump RMP close to equil of K to keep cell from spontaneous contraction |
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phase 1 of ventricle
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repol
inactivate: Na+ voltage T type Ca+ A type K+ open for rapid repol inactivates quickly too |
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phase 2 of ventricle
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plateau
depolarization and K+ channels blocked by Mg and polyamines keeping depol currents unbalanced L type Ca+ Na+/Ca+ exchanger couple with Na+/K+ pump |
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phase 3 of ventricle
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final repol
delayed K+ current activation |
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K+ slow delayed
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slow repolarization during phase 3
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phase 4 in SA node
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RMP
dynamic/slow depol Na+ leak channel pacemaker currents - cation and t type Ca+ |
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phase 0 in SA node
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no voltage Na+ channels
L type Ca+ channel which are slower depol |
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phase 3 in SA node
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repol
delayed K+ current stronger and quicker |
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why no phase 2 in SA node
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small group of purkinje cells whose only job is to initiate AP
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long QT syndrome
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defective K+ channel of fast Na+ channel
long AP -> SA node expects ventricular cells to be hyperpolarized so when they aren't bc of the the long repolarization; SA node ends up doing nothing and skips beats |
