I'll give this one a shot, and others can correct me if I get it wrong.
There are two types of conduction that can occur in an axon - straight
electrical (like in a wire) and the action potential. Of the two, straight
electrical conduction is faster and not as costly metabolically. However,
the signal degrades the farther it travels. An action potential is slower
and more costly, but it doesn't degrade. What happens is that an action
potential is triggered, the signal travels quickly through a sheathed
portion of the axon (but degrades). At the next Node of Ranvier another
action potential is triggered and so on. As I understand it, the nodes of
Ranvier act something like a booster station in the electric grid.
Hope this helps,
Larry
--On Tuesday, April 04, 2000 9:20 AM -0400 "Hetzel, Roderick"
<[EMAIL PROTECTED]> wrote:
> Can someone who is more biologically-minded than me please explain exactly
> how myelin sheaths faciliate the transmission of the neural impulse. I
> understand the impulse is transmitted by the changing permeability of
> sequential sections of the cell membrane, but am not sure how the myelin
> sheath and the nodes of Ranvier fit in with all of this.
>
> Thanks in advacne.
>
> _______________________________________
> Roderick D. Hetzel, Ph.D.
> Assistant Professor and Attending Psychologist
> Department of Anesthesiology
> University of Rochester Medical Center
> Pain and Symptom Treatment Center
> 2337 Clinton Avenue South
> Rochester, New York 14618
> 716-275-3524 (phone)
> 716-473-5007 (fax)
> [EMAIL PROTECTED] (email)
>
*********************************************************
Larry Z. Daily
Post-doctoral Research Associate
Department of Psychology
Carnegie Mellon University
phone: (412) 268-4194
email: [EMAIL PROTECTED]
Web: http://www.andrew.cmu.edu/user/ldaily/index.html
