The truth is out there

kkollins at pop3.concentric.net kkollins at pop3.concentric.net
Thu Nov 26 22:25:12 EST 1998


I'll be grateful if you continue your discussion... Learning's Fun. ken collins

Andrew K Fletcher wrote:

> Hi Frank, Hi Ken,
>
> The flow of water in plants and trees is relevant to this discussion, it was
> my interest in this that led directly to my working with spinal cord injury,
> ms and other neurological conditions.
> "
> Frank, could you please summarise the content of 'this wonderful process'
> referred to in your posting and its relationship with how water reaches the
> leaves of trees.
>
> The flow of cerebrospinal fluid as described in Principles of Anatomy and
> Physiology is as follows.
>
> The entire central nervous system contains  between 80 and 150 ml (3 to 5oz)
> of cerebrospinal fluid, colourless fluid of watery consistency. Chemically
> it contains, proteins, glucose, urea and salts. It also contains some
> lymphocytes.
>
> With regard to its circulatory function, cerebrospinal fluid delivers
> nutritive substances filtered from the blood to the brain and spinal cord
> and removes wastes and toxic substances produced by brain and spinal cord
> cells.
>
> It then goes on to illustrate the path of the circulation of CSF.
>
> The flow of cerebrospinal fluid as described in Advanced Human Biology: J.
> Simpkins, J.I.Williams, is as follows.
>
> Pressure compensation
> CSF is produced from and returns to the blood passively in response to
> pressure differences between the blood and CSF. The effects of increases in
> blood pressure distending intercranial vessels can thus be reduced as more
> CSF is produced.
>
> Page 125 The beating of the cilia cells sets up currents in the
> cerebrospinal fluid, thus helping the circulation of metabolites. Astrocytes
> are connected to the bases of ependymal cells which may assist exchange of
> metabolites between CSF and neurons in the central nervous system.
>
> Fig 14.43, page 285 shows a simple drawing which illustrates the circulation
> of fluids by arrows from the choroid plexus down one side of the spine and
> up another side, it also shows a flow over the the surface of the brain,
> indicated by an arrow on both sides.
>
> I did read an article, which was a reprint of text from another physiology
> book, which I can't find, that stated something along these lines.
> Circulation in the CSF occurs due to respiration, postural, and circulatory
> influences.
>
> Ken Collins wrote:
>
> I've not studied it, but I expect the cerebrospinal fluid flows through
> active
> dynamics... when it's produced, it goes into the ventricles, more is
> produced...
> what was produced earlier flows to "get out of the way" of what's just been
> produced. I don't know where the "drain" is... expect it's a distributed
> thing,
> too. ken Collins
>
> Original post.
>
> >>Could someone therefore sum up the accepted mechanism for circulation
> >in the
> >>cerebrospinal fluid, so that we have an independent benchmark for
> >further
> >>discussions? Only then will we see if this road leads us to any
> >conclusions.
> >
> >
> >- - - - - -(snip) - - - - - - -
> >F. Frank LeFever, Ph.D. wrote.
>
> >I won't comment on his itemizing the forces by which water could be
> >lifted up into trees and then demanding to know how this happens.
> >(Incidentally, I found treatment of this wonderful process in Murchie's
> >"The Seven Mysteries of Life" fascinating; too bad he got spooky on the
> >last 2-3 mysteries...)
>
> >However, I too am interested in CSF, and attended a satellite
> >conference (sponsored by NSF, prior to the Society for Neuroscience
> >meeting early this month) on CSF as a communications system.  Among
> >other things, problems of its circulation were considered.
> >
> >F. Frank LeFever, Ph.D.
> >New York Neuropsychology Group






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