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Re: CO2, gasping

>Date: Thu, 13 Jan 2000 12:39:27 -0600
>From: Rebecca Allbritton <rda3507 at acs_tamu.edu
>>On Wed, 12 Jan 2000, George Booth wrote:
>>> Many people miss this point. With high O2 AND high CO2 in the water,
>>> CO2 cannot leave the blood (meaning O2 can't enter the blood; they
>>> bind to the same site on the hemoglobin molecule) and the animal
>>> asphyxiates. With low O2 AND low CO2 in the water, CO2 can leave the
>>> blood but O2 can't enter and the animal asphyxiates.

Karla (my biochemist wife) pointed out that I was oversimplifying this
process. CO2 and O2 have different affinity constants so there is some
complication with the actual concentrations and other details. But the
concept was OK.

>No, no, no -- you've forgotten about active transport, which is one way an
>organism achieves higher concentrations of the desired material (some
>gasses, e.g. O2, & some other molecules) inside the cell than outside, and
>lower concentrations of unwanted materials inside than outside. 

Karla said that active transport wasn't a factor in this. I'm taking about
gas exchange in the gills, not gas exchange at the cell level.
Unfortunately, she didn't elaborate. 

George Booth, Ft. Collins, Colorado (booth at frii_com)