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Re: Breathing

On Sun, 11 Apr 1999, Patrick Norton wrote:

> >Um, because gills don't work in air?<
> Um, I wish things were so simple.
> >In a sense, yes, but it is unable to extract oxygen from *air*.  A gill,
> for some reason, can only exchange gases effectively with water.<
> Actually, gills can extract oxygen from air as long as they (the
> gills)remain moist. The efficiency of that exchange, of course, changes
> based on the characteristics of the fluid medium.

I thought that the main reason gills wouldn't work for terrestrial
vertebrates' respiration was that surface tension would collapse the
higher-order filaments, thereby severely reducing the available surface
area for gas exchange.  Not unlike what would happen to our lungs if we
lost our surfactant.

*   dchwang@itsa.ucsf.edu   *   xenopathologist at large!   *