Richard Norman rsnorman at
Wed Sep 20 21:51:49 EST 2000

"Electric current" is the movement of charge.  In metals, the charge
carriers are electrons, in semiconductors it can be electrons or
holes, in electrolyte solutions and in plasmas, it is ions.  But
electrically it is all the same.  One of Kirkhoff's laws is that the
sum of currents at any node must be zero.  In neurophysiology,
part of that current can be electronic (a stimulating current flowing
in an electrode), part can be intracellular ionic carried probably
by K+ in the intracellular fluid, part can be transmembrane ionic
carried by, say, Na+ flowing through ion channels, and part can
be transmembrane capacitative or "displacement current", not
physically carried by a charged particle but rather by the change
in electric field of the dielectric medium.  Still the sum of all these
disparate currents must total zero.

""Richard L. Hall"" <rhall at> wrote in message
> Sure.  Ion diffusion carries electrical charge and current moves with
> the net diffusion of positive charges.  Ion channels are important
> because they regulate current flow in and out of a cell.  Ion
> channels are not needed for current spread throughout body fluids
> which is why a strong electrical shock can stop your heart.
> Electricity in the body is generated by the net movement of ions
> between the intracellular and extracellular compartment.  Typically
> asymmetries in ionic distributions create gradients for ionic
> diffusion and current flow.  Muscle activity directly generates more
> current flow through the ecf than neural activity.  This is why it is
> easy to measure the electrocardiogram.  It is possible to measure
> cortical electroencephalograms but the magnitudes are smaller and the
> complexity greater.
> rlh
> >In reponse to a message already deleted...
> >
> >Can currents through ion channels be termed electric?  Why not?  I don't
> >think electrons have to be involved do they?  What about the poor old
> >electric fish with electric organs?  Isn't their "electricity" generated
> >via ion channels?  Ionic current is more appropriate though, I must
> >
> >Gary G Wilson
> >Center for Molecular Recognition
> >Columbia University
> Richard L. Hall, Ph.D.
> Comparative Animal Physiologist
> University of the Virgin Islands
> 2 John Brewers Bay
> St. Thomas, U.S.V.I. 00802
> 340-693-1386
> 340-693-1385 FAX
> rhall at
> "Live life on the edge...the view is always better"  rlh
> ---

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