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10 Cards in this Set
- Front
- Back
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membrane pot of sinus node
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-55 to -60mV
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sinus node has slow leak of _____ at rest pot of -55mV
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Na ions
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why is the SA node at a more positive resting pot than ventricular muscle?
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leaky to Na and Ca ions
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conduction velocity of atrial and ventricular muscle?
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0.3 to 0.5 m/s
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conduction velocity of purkinje fibers?
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2 to 4 m/s
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the cardiac pacemaker
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SA node
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autorhythmicity is due to _______
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leakiness to ions (sodium)
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depolarization of the SA node is due to_________
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opening of the slow calcium channels (h gates closed)
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Each time A-V conduction ceases, the ventricles often do not start their own beating until after a delay of 5 to 30 seconds. This results from the phenomenon called ___________
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overdrive suppression
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stokes-adams syndrome
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periodic fainting spells cuased by intermittant A-V block. (Overdrive suppression causes fainting, ventricular escape causes recovery)
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