From owner-biophysics@net.bio.net Wed Nov 25 22:00:00 1998 Path: biosci!news.stanford.edu!newsfeed.berkeley.edu!btnet-peer!btnet!news-lond.gip.net!news.gsl.net!gip.net!dispose.news.demon.net!demon!news.demon.co.uk!demon!naturesway.demon.co.uk!not-for-mail From: "Andrew K Fletcher" Newsgroups: bionet.biophysics,bionet.microbiology,bionet.neuroscience Subject: Re: The truth is out there Date: Thu, 26 Nov 1998 10:12:41 -0000 Organization: OASIS Concepts Ltd Message-ID: <912075256.24982.0.nnrp-03.d4e44203@news.demon.co.uk> References: <721spg$cr7$1@nnrp1.dejanews.com> <36449D67.378533CC@pop3.concentric.net> <36449FE2.313F8F3@pop3.concentric.net> <36477CA4.D2FED10@pop3.concentric.net> <3647B373.953F0A70@pop3.concentric.net> <3649B0AF.E720E242@psci.net> <364AAB63.C5056FB9@pop3.concentric.net> <364B5C6D.75E14B08@indiana.edu> <72s9eb$2fe@apple.telalink.net> <36523785.484B17DE@pop3.concentric.net> <912019876.8168.0.nnrp-08.d4e44203@news.demon.co.uk> <73im3f$ogr@dfw-ixnews3.ix.netcom.com> NNTP-Posting-Host: naturesway.demon.co.uk X-NNTP-Posting-Host: naturesway.demon.co.uk:212.228.66.3 X-Trace: news.demon.co.uk 912075256 nnrp-03:24982 NO-IDENT naturesway.demon.co.uk:212.228.66.3 X-Complaints-To: abuse@demon.net X-Newsreader: Microsoft Outlook Express 4.72.2106.4 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4 Lines: 89 Xref: biosci bionet.biophysics:4574 bionet.microbiology:15164 bionet.neuroscience:26023 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 .