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Basic Neuron Questions

BilZ0r BilZ0r at TAKETHISOUThotmail.com
Sat Apr 5 02:11:39 EST 2003


neo55592 at hotmail.com (Neo) wrote in news:4b45d3ad.0304042219.2e905a42
@posting.google.com:

> 1. What is the average refractory period (the duration a neuron needs
> to recover before being able to create a successive action potential)?
> 2. If neurons were arranged linearly, approximately how neurons will a
> signal have traveled thru during an average refractory period? TIA
> 

The ABSOLUTE refractory period is between 4 and 5ms (the time it takes 
for potassium channels to close). But a neuron needs a much larger 
stimulation to fire the directly after the absolute refractory period. 
The relative refractory period is any time from the end of the absolute 
refractory period untill the neuron can generate an action potential by 
the normal level of stimulation.

If we assume were dealing with a small, unmylinated neuron the AP 
propigates at about 5 meters a second, or 5mm a millisecond, so in 4-5ms 
it travels 20-25mm, about a 10th of an inch. 

If were dealing with a large mylinated neuron, were talking 100-120meters 
a second, to 100-120mm a millisecond, so in 4-5ms thats 400-600mm or 
about half a meter. (Someone correct me if my maths is wrong).



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