Re: [PSUBS-MAILIST] life support method?

["Alan D. Secor" <secor@btv.ibm.com>]

You are right, I just didn't follow though with my explanation...the 
bottom line is your body uses O2 and expels CO2...if the CO2 is removed 
and the O2 isn't replaced, the net result is a reduction of cabin 
pressure.

Al

>
>> 2.) If no supplemental O2 were added, the cabin
>> pressure would gradually 
>> decrease due to the O2 in the air being metabolized
>> by your body.  You 
>> are correct in assuming that if O2 were released
>> into the cabin at the 
>> rate our body metabolized it, the system would
>> remain fairly balanced.
>
>Actually,
>
>The decrease in pressure in the cabin is NOT caused by
>the "metabolism" of 02 by the body, but rather by the
>conversion of the CO2 to a non-gasous state in the
>form of a chemical compound formed between the
>absorbant and the CO2 (hence the heat/H20 emitted).
>Respiration requires 02, but yields as a product CO2,
>which results in no net change in air pressure. It is
>the scrubber which is decreasing the air pressure, not
>the person. 
>
>FOR INSTANCE: (Boring Biology stuff for most)
>If you lock a person such as yourself in an airtight
>room, they will eventually die because their bodies
>expel C02 (a product of catabolic metabolism) and
>convert oxygen to H20 by dumping electrons onto it at
>the end of the electron transport chain within the
>mitochondria of their cells. When you open the door of
>the room, the air will be saturated with CO2, but the
>pressure will still be at or very, very near 1 atm.
>Most people think that the CO2 a person breathes out
>is the oxygen they breathed in with a C attached to
>it. Actually, it is a completely different oxygen that
>was stripped of a carbohydrate during a catabolic
>reaction.
>
>
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--
Alan D. Secor
e-mail: secor@btv.ibm.com