refrac, repolariz

eliot gelwan eliot.gelwan at channel1.com
Fri Apr 17 15:37:46 EST 1992


On 04-17-92 ALLEN SMITH wrote:

AS>Strictly speaking, repolarisation time is the time it takes for the
AS>membrane potential to return to rest from the peak of the depolarising
AS>phase of the action potential.  This is generally less than 1ms in
AS>normal neurones.  Following repolarisation, there is a period called
AS>the refractory period during which it is impossible/difficult to evoke
AS>subsequent action potentials.  The length of this period is very
AS>variable from neuron type to neuron type and can be hundred of ms
AS>long, or only a few tens...  'it depends'.
AS
AS        There seems to be a contradiction in the definitions of refractory
ASperiod and repolarization time. What's the name for how long it takes
ASbefore a neuron can send a signal again?

That's what he said -- refractory period is how long it takes
before a neuron can send a signal again, "the...period during
which it is impossible/difficult to evoke su=bsequent action
potentials." (Action potential = propagation of signal). In
essence, repolarization time is a mechanically defined term,
refractory period a functionally defined one. I think it's
invariably true that refractoriness is resolved by a *tendency*
toward repolarization, but not necessarily return to baseline.
That's the difference.



                                        012 eliot 210
Internet: eliot.gelwan at channel1.com
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