I can follow up a little with the sodium-potassium pump question, with
some more detail, but Ianae (I am not an expert):
There are (at least) two forces at work on the ions (sodium and
potassium, which are both positive ions), the electrical gradient (more
potassium inside the cell and more sodium outside, and with the help of
some anions and Ca+, you get a net negative potential across the
membrane; the Na+ ions want to move across the membrane and the K+ want
to stay inside) and the concentration gradients (more K+ inside wants to
diffuse to low-K+ concentrations outside; high Na+ outside wants to
diffuse to low-Na+ inside). The pump works to push Na+ out and pull K+
in, and thus helps maintain the negative membrane resting potential.
So if the pumps shut down, as can happen with some toxins, then the Na+
would pass through the membrane pretty quickly (pushed there by the
concentration gradient and pulled there by the electrical gradient) and
the K+ ions will diffuse out (more slowly, because the electrical
gradient works against diffusion) of the axon because of the
concentration gradient. As the potential depolarizes, then the
electrical gradient will not longer act as much, and Na+ will move more
slowly and K+ more quickly until the voltages on both sides of the
membrane are the same.
Net result is no membrane potential, no action potentials, and yes, all
your neurons would quit working, and then that would be that.
This is simplistic (given my basic understanding), but correct as far as
it goes (I think, and welcome correction if not!).
HTH,
m
--
Marc Carter
Assistant Professor, Itinerant Scientist,
Inveterate Skeptic, Former Surfer.
---
[A] long habit of not thinking a thing wrong, gives it a superficial
appearance of being right.
------
Thomas Paine, _Common Sense_ (1776)
-----Original Message-----
From: DeVolder Carol L [mailto:[EMAIL PROTECTED]
Sent: Thursday, September 30, 2004 7:56 AM
To: Teaching in the Psychological Sciences
Subject: RE: question from student
Hi Nina,
A couple of very rushed answer to your questions--when someone has
damage to Wernicke's area, they very often cannot understand their own
speech, so they don't comprehend what it is they've said--hence a very
garbled form of speech comes forth. In other words, they are fluent, but
their speech is meaningless.
If all of the billions of sodium-potassium pumps were not working, the
person would be dead.
Hope these make sense, gotta rush to class, I'm sure someone else will
be able to proved more concise and coherant answers.
Carol
-----Original Message-----
From: Nina Tarner [mailto:[EMAIL PROTECTED]
Sent: Thursday, September 30, 2004 5:23 AM
To: Teaching in the Psychological Sciences
Subject: question from student
Hi all,
We were discussing Wernicke's Area in Intro. the other night and a
student said that if damage to Wernicke's Area meant the person could
not understand spoken language did that mean they couldn't even
understand themselves? I think they were referring to when a person
talks to themslelves in their own mind.
Another student question that was asked in which I couldn't answer was
what would happen if a person's sodium-potassium pump was not working?
What would happen to the positive sodium ions and negative potassium
ions?
Thanks for any help you can provide,
Nina
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