From: Steven Eiger (eiger@montana.edu)
Date: Tue Mar 21 2000 - 08:54:50 PST
Message-Id: <l03102800b4fd5730ab85@[153.90.241.107]> Date: Tue, 21 Mar 2000 09:54:50 -0700 From: Steven Eiger <eiger@montana.edu> Subject: Re: pinhole Re: numb
>> 5) How come you get numb when you're cold?
>
>Probably same thing for a different reason. Your body conserves heat by
>closing down capillaries to the extremities.
>
Biological molecules are very sensitive to temperature (Q10). Ion channels
etc do not work properly at very cold temperatures, thus signals can not be
transmitted. I wonder about the compression as well as; Nerves can
transmit action potentials in the absence of oxygen, ATP, glucose for many
minutes, probably hours, thus the compression on the nerves may be acting
by changing the ionic conductance within the cell by lowering the
cross-sectional surface area which the current flows down the nerve. In
certain disease, eg. MS, the length constant is changed by demyelination
and people suffer from numbness and paralysis, changing the cross sectional
area would also do this, but the compression time can also cut off blood
flow, whether it is long enough to efffect the ionic concentration
gradients by stopping the pump is unclear to me.
Steven Eiger, Ph.D.
Departments of Biology and the WWAMI Medical Education Program
Montana State University - Bozeman
Bozeman, MT 59717-3460
Voice: (406) 994-5672
E-mail: eiger@montana.edu
FAX: (406) 994-3190
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