Q: dendrites/gates

Kalman Rubinson kr4 at nyu.edu
Sun Mar 20 19:55:18 EST 2005


On Mon, 21 Mar 2005 06:32:10 +1100, Matthew Kirkcaldie
<m.kirkcaldie-remove at unsw.edu.au> wrote:

>In article <1111329343.528759.36260 at z14g2000cwz.googlegroups.com>,
> mimo_545 at hotmail.com wrote:
>
>> Thanks, thats helped me out a lot.
>> I was wondering if the Nodes of Ranvier
>> had an effect like bleeding or leaching
>> a current.
>
>Quite the opposite, they allow the current to keep circulating, and 
>speed up the axon's conduction.  

Well, technically, the nodes do slow conduction since that is where
the time-consuming task of regenerating the AP occurs.  The
transmission through the internodal portions of the axon is much
faster.  

>The axon membrane has to be exposed in 
>order for action potentials to occur.

Yup. That regeneration is essential for the continued conduction of
the AP but an unmyelinated axon generates an AP along its entire
length but conducts more slowly. .  It is the myelination that is
responsible for the speed (reduced capacitance and all that stuff).

Kal



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