Re: [PSUBS-MAILIST] life support method?

[S W <stephenwhite20@yahoo.com>]

> 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.


__________________________________________________
Do You Yahoo!?
Kick off your party with Yahoo! Invites.
http://invites.yahoo.com/