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>> >> Chuck, >> >> >> Obviously O2 gets into a pressurized tissue somehow but I can not = >> picture it migrating passively by random walk diffusion against the = >> onslaught of a pressure gradient even though that gradient is surely = >> quite small.<< >> >> I fear this physiology may be getting a little out of my league, but = >> here is my best guess for how it works. Any DMO/HMOs out there want to = >> take a stab at it and wade in?? >> >> Diffusion works against pressure gradiants all the time. Your blood is, = >> at the capillary level, something like 40mm Hg higher than the = >> surrounding tissue pressure. It does decrease somewhat as it travels = >> through the capillary, but it has to remain higher than the surrounding = >> tissue pressure, or the capillary would collapse, and blood would not = >> circulate through it. Yet carbon dioxide and other waste products = >> diffuse from the cells into the blood stream just the same. >> =20 >> >> However, another factor that figures into this is that the release of = >> O2 from Hb raises the total plasma gas tension.<<=20 >> >> I took a gander through one of my physiology textbooks, at the oxygen = >> dissociation curve for hemoglobin. It seems that as oxygen tension = >> increases, more of it is bound to the hemoglobin, so at higher tensions, = >> the oxygen would not be released at all - the only oxygen being = >> metabolized is that which is dissolved in the plasma.=20 >> >> RIch L >> >> ------=_NextPart_000_0073_01BE6438.FD11C920 >> Content-Type: text/html; >> charset="iso-8859-1" >> Content-Transfer-Encoding: quoted-printable >> >> <!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 HTML//EN"> >> <HTML><HEAD> >> <META content=3Dtext/html;charset=3Diso-8859-1 = >> http-equiv=3DContent-Type><!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 = >> HTML//EN"> >> <STYLE></STYLE> >> >> <META content=3D'"MSHTML 5.00.0910.1309"' name=3DGENERATOR></HEAD> >> <BODY bgColor=3D#ffffff> >> <DIV> </DIV> >> <DIV style=3D"FONT: 10pt arial"> </DIV> >> <DIV><FONT size=3D2>Chuck,</FONT></DIV> >> <DIV> </DIV> >> <DIV><FONT size=3D2>>> Obviously O2 gets into a pressurized tissue = >> somehow=20 >> but I can not picture it migrating passively by random walk diffusion = >> against=20 >> the onslaught of a pressure gradient even though that gradient is surely = >> quite=20 >> small.<<</FONT></DIV> >> <DIV> </DIV> >> <DIV><FONT size=3D2>I fear this physiology may be getting a little out = >> of my=20 >> league, but here is my best guess for how it works. Any DMO/HMOs out = >> there want=20 >> to take a stab at it and wade in??</FONT></DIV> >> <DIV> </DIV> >> <DIV><FONT size=3D2>Diffusion works against pressure gradiants all the = >> time. Your=20 >> blood is, at the capillary level, something like 40mm Hg higher than the = >> >> surrounding tissue pressure. It does decrease somewhat as it travels = >> through the=20 >> capillary, but it has to remain higher than the surrounding tissue = >> pressure, or=20 >> the capillary would collapse, and blood would not circulate through it. = >> Yet=20 >> carbon dioxide and other waste products diffuse from the cells into the = >> blood=20 >> stream just the same.</FONT></DIV> >> <DIV><FONT size=3D2></FONT> </DIV> >> <DIV><FONT size=3D2>>> However, another factor that figures into = >> this is=20 >> that the release of O2 from Hb raises the total plasma gas = >> tension.<<=20 >> </FONT></DIV> >> <DIV> </DIV> >> <DIV><FONT size=3D2>I took a gander through one of my physiology = >> textbooks, at the=20 >> oxygen dissociation curve for hemoglobin. It seems that as oxygen = >> tension=20 >> increases, more of it is bound to the hemoglobin, so at higher tensions, = >> the=20 >> oxygen would not be released at all - the only oxygen being metabolized = >> is that=20 >> which is dissolved in the plasma. </FONT></DIV> >> <DIV> </DIV> >> <DIV><FONT size=3D2>RIch L</FONT></DIV></BODY></HTML> >> >> ------=_NextPart_000_0073_01BE6438.FD11C920-- >> -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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