Could a cell membrane provide an electromagnetic shield ?

k p Collins kpaulc at [----------]earthlink.net
Wed Feb 11 15:11:36 EST 2004


I stand on what I've posted.

Further comments, below.

"r norman" <rsn_ at _comcast.net> wrote in message
news:9gbk20h70l6ng014q6socngubc9qi6g96e at 4ax.com...
> On Wed, 11 Feb 2004 08:18:58 GMT, "k p  Collins"
> <kpaulc@[----------]earthlink.net> wrote:
>
> >Hi Dr. Norman,
> >
> >"r norman" <rsn_ at _comcast.net> wrote in message
> >news:077j20drks8gq72pv9f52dj088phro99m2 at 4ax.com...
> >> [...]
> >
> >>Incidentally, the membrane capacitance is
> >> pretty close to 1 microfarad/square
> >>centimeter or 0.01 farad/m2.
> >
> >I =only= want to try to convey a 'new'
> >position with respect to such 'membrane
> >capacitance', and I'm not expecting you
> >to reply. [It's too-hot, just now. I under-
> >stand.]
> >
> >In my view, what you refer to as a
> >"membrane capacitance" is not a
> >"capacitance", but a result of active
> >ionic pumping that maintains the
> >resting potential.
> >
> >In "capacitance", the "capacity"
> >fills-up and the result is a =passive=
> >storage, not anything that is actively
> >maintained.
> >
> >I'm not saying it well enough. What
> >I'm getting at is that the 3-D energy-
> >dynamics that maintain the resting
> >potential are the wellsprings of
> >information-content. That is, they
> >are not uniform, as is a capacitor's
> >passive response, but, through stuff
> >like gate-location and ionic response
> >selectivity, exist as they do as activa-
> >tion-dependent =results= of prior
> >neural experience.
>
> Ken, I do understand that you have a world-view that includes
> something about 3-D energy-dynamics.  Unfortunately, that view
> deviates from what everyone else in the world considers the state of
> affairs.  I have studiously avoided getting into long discussions with
> you about your ideas and simply don't bother reading them.  I must say
> here that, when you are not into your energy-dynamics thing, you do
> have some intelligent ideas to contribute.  However, your alternative
> non-traditional theories  dominate almost all of your posts.

I stand on what I've posted.

> I will abide by classical electricity and magnetism that has served
> humankind so successfully for about 150 years (quantum mechanics and
> more recent theories aren't necessary for phenomena at the level we
> are describing).

I stand on what I've posted.

> The membrane is composed of a lipid bilayer through which electrical
> charge cannnot pass.  That is: ions cannot move across the lipid
> bilayer.  That is: the lipid bilayer is a dielectric that separates
> charge.  You can get a kind of current to flow across it --
> displacement current -- which obeys the law I = C dV/dT.  An
> electrical component that obeys this law is called a capacitor.

I stand on what I've posted.

> The membrane also contains ion channels through which charged
> particles can move, carrying current.  The rate of current is, to a
> good degree, directly proportional to the "forces" acting on the
> charge.  Since there are both diffusional "forces" and true electrical
> forces, the ionic current for substance x obeys the law
>           Ix = gx (V - Ex)
> where gx is a constant called conductance and Ex is the Nernst or
> equilibrium potential for substane x,  Ex = RT/F ln [X]/[X].  An
> electrical component in which current is proportional to voltage is
> called a resistor.  The extra term in the ionic current equation can
> be represented by a voltage source.

I stand on what I've posted.

> There is an enormous body of experimental work dating back some 50
> years now confirming the validity of this "ionic theory".  In fact, no
> one even calls this the "ionic theory" any more, it is simply the way
> membranes work.

I stand on what I've posted.

> And the ion pumps do NOT really maintain the resting potential

:-]

I stand on what I've posted.

> and, of
> course, have absolutely nothing to do with capacitance, apparent or
> real.

:-]

I stand on what I've posted.

> The ion pumps maintain the concentration gradients across the
> membrane.

:-]

Yeah, and =that= is where all the "capacitance"
arises - "ions piling up, waiting to get through the
gates".

If the ionic concentrations were not actively
pumped, there'd be no concentration-gradient
differentials.

The difference between our positions is that
I've gone-beyond the 'canned solution' to
Explain how and why what has been referred
to as "membrane capacitance exists.

Even the lipid bilayer breaks dowh if the active
pumping ceases. Kill all the pumps, and you
will see this.

The end result is called "adpopsis".

The difference between our positions
matters.

What Science does is 'move toward' Truth
with respect to what matters.

So, clearly, I'm doing Science.

I stand on what I've posted.

> The potential is caused by the differential selective
> permeability of the membrane and the ion concentration gradients.

The differential selectivity is 100% Determined
by the active pumps and selectively-activated gates.

The membrane potential would be nothing
without the active pumps and the selectively-
activated gates.

And, if you look, you'll see that, in my prior
discussions [both recent, and former], I've
Explained how the selectivity happens.

One =cannot= get-there using only the
"Classical" equations.

The "Classical" equations are 'static'. In and
of themselves, they actually 'blind' folks to
everything that needs to be seen.

Which was what I was discussing.

[If anyone looks, they'll see that =all= of my
discussions have the 'meta'-purpose that
derives in eliminating that which 'blinds'
folks to seeing what needs to be seen. Folks
'take-offense' - 'move away from' - be-cause
of 'blindly'-automated TD E/I-minimization.

I'm used to it, and just continue giving folks
that which eliminates the 'blindness'.]

I stand on what I've posted at great Cost,
Knowing that, eventually, folks'll get-it.

> One proof is to kill the pump.

Which, to the degree that such is done,
=only= Proves the position I've discussed.

> Except for a small term caused by the
> electrogenic action of the pump (net charge transport across the
> membrane), the potential remains until the ion movements eventually
> alter the concentrations.

=All= of this occurs as the =sole= consequence
of the actions of the active pumps and selective
gating.

I stand on what I've posted.

> Another demonstration is the success of the
> Goldman constant-field equation in describing electrical potential in
> virtually all experimentally tested situations.  This equation
> includes only concetrations and permeabilities.

The concentrations Exist be-cause of active
pumping.

The permeabilities Exist be-cause of selective
gating.

I've explained how =selective= gating occurs.

I stand on what I've posted.

>  Approximately 85%-90% of the 60+ students in my intro neurobiology
> class know all of this.  It was the subject for the most recent exam.
> You should sit in on my lectures!

I'd like to do exactly that - somewhere.

But folkd's not 'enjoy' having-me-there,
be-cause I've this 'weirdness' in which
I'm always 'moving toward' what's not
already in the books.

In the future, you will be Lecturing on the
stuff I've discussed.

I =do not= 'toss-out' the Triumphs that have
come before.

All I do, in all I do, is 'move toward' what
hadn't  realized is =in= the former Triumphs.

I stand on what I've posted.

[I forwarned that the stuff that I discussed
in my reply to your post is "too-hot", and
encouraged you to not reply, so don't be
'angry' with me. It's just that, where I am,
Science 'moves toward' Truth.]

Thank You for the work inherent in your
replying, Dr. Norman.

K. P. Collins







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