drhouse
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What happens to conductance of Na and K during phase of repolarization, compared to resting state
Na conductance--------------K conductance
A. inc rease------------decrease
B. increase-------------increase
C. same--------------increase
D. same --------------decrease
E. same----------------same
F, decrease------------decrease
Edited by drhouse on 07/25/07 - 08:03 PM
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| P4a99
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C ... ?
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| d
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i wuld have said decrease - increase. But since there is no such option so I go with C
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| silver
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CCCCCCCCCCCCCC
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| drhouse
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think again guys, its compared to resting state
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| P4a99
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please dont tell me its: same .... same ! (cuz i dont think that that would be fast enough for the repolarization process)
Na channels are usually close ... so : same
K channels are usually open but we need the K to get out of the cell very rapidly ... so : increase
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| drhouse
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Ready for surprise,,,,,,,,,,,,,,,
dont follow knee jerk guys...
conductance of both Na and K is increased compared to resting state..
Edited by drhouse on 07/26/07 - 12:16 PM
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| d
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drhouse - can u explain for sodium !
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| P4a99
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arnt you talking about (repolarization) ? Na channels already closed a long time ago!
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| drhouse
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yeah.
most of the time we think that Na channels are closed during repolarization. but the process is like this.
during depolarization Na channels open and increases its conductance, it reaches maximum conductance just near the peak of the action potential. Now during repolarization Na channel start closing, but its not like we turn off switch and light is off. so during repolarization Na channels are in process of closing. so its conductance is decreasing but still its higher compared resting state...
refer to the graph of action potential and conductance from physio kaplan
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| P4a99
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drhouse wrote:
but its not like we turn off switch and light is off
this is how i thought it was ...
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| P4a99
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The initial repolarization (phase 1) is dependent on the inactivation of Na+ channels and the opening of a transient K+ channel. Repolarization (phase 3) is produced by the inactivation of Ca2+ channels and the activation of the delayed rectifier K+ channels.
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| simi
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drhouse thanks for the good qs.
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| Ig F
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very smart drhouse..........
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