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Excuse my ignorance, John, but I'm confused on this one... (I THOUGHT I 
was understanding the oxygen window thing)

>Metabolism does not grow linearly with depth, but the amount of 
>DISSOLVED oxgyen does increase linearly with depth, and it is
>essentially the decrement in the dissolved oxygen partial pressure
>that creates the inherent unstaturation called the oxygen window.

Let's assume that you're inspiring some ppO2.  (Assumption in this 
sentence) There is some pressure gradient between the inspired O2 and the 
gas pressure of the O2 dissolved in your bloodstream at the moment it 
leaves the lungs (i.e. I'm assuming that the gas pressure in the blood 
stream does not manage to equalize to the gas pressure in the lungs).

1) Does this differential get included in the O2 Window?  (Assumption: I 
don't think so since it's always present)

2) As the blood stream is cirulated, the body tissues utilizes O2 and 
returns a (lower) quantity of CO2 (okay, a carbonic of some sort).  As I 
understand it, this is the "O2 window".

Now, since the body (all things except pressure being equal) uses the 
same amount of O2, I would think that the O2 window _narrows_ with 
increasing pressure, not opens.  The reasoning goes this way (and I 
present it so that you can show me where I went wrong in my understanding):

The next paragraph contains assumptions and conclusions

Let us assume that the body metabolizes some amount of O2, call it "X".  
Let us assume that there is some amount of O2 available to the body 
tissues, call it "Y".  Y varies directly with pressure.  The gas pressure 
is Y/K where "K" is the volume available to diffuse the O2.  Note that 
"K" will remain fixed (except for the amount of urea, flatulence, or 
other excretions).  The O2 window is described (in simple terms) by Y/K - 
(Y-X+cX)/K where "c" is the proportion of X that is returned via CO2.  
X+cX is a constant, which we'll call "C".
Y/K - (Y-C)/K = C/K.

::sigh:: So, obviously, there's some hole in my understanding of this 
process or the definitions of what you said.

According to what your paragraph means to me, the inherent unsaturation 
is the same as the inherent gas gradient across tissues.  Doesn't that 
remain constant no matter depth?  Arrrgggh. No matter which way I try and 
reason through this, I keep coming to the same, erroneous, conclusion.

::totally confused now::


        -- Kevin --
        kevink@ap*.co*

It is hard to disagree with a pro-survival decision,
     It is even harder to engage in prolonged arguments
          with someone who consistently makes anti-survival decisions.

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