Re: MFW journal club - lifting weights makes you thin, cures diabetes?

Dnia 2008-02-11 Tom Anderson napisał(a):
On Mon, 11 Feb 2008, Andrzej Rosa wrote:

Tom Anderson wrote:

No. That only works if the process is near equilibrium.

Which means, that there should be enough time for changes of temperature
to not result in changes of pressure. It works like that by default in
condensed phase.

Or do you mean, that a cell can't be considered a closed system?

That.

Well, actually, i meant something else entirely, but i've realised i was
talking nonsense, so i'm going with that instead.

For fast reactions it shouldn't matter, and in bulk of muscle mass it
shouldn't matter at all.

On the contrary! A *lot* of heat escapes the cell.

And enters another one, doesn't it?

[...]
For this process, the amount of energy 'lost' to entropy (really,
the amount of energy given up to drive the reactions forward quickly)
is fixed by the stoichiometries of the enzymes, which is what i looked at.
Except i didn't account for the 'clutch slip' by leakage of protons across
the mitochondrial membrane, which can be a significant amount.

I managed to never learn biochemistry on this level (which wasn't all that
easy), so I can't comment here. (But your wording regarding entropy, energy
and kinetics makes me cringe a bit. ;-))

My apologies! What's wrong with it?

You don't lose energy to entropy. Entropy is an information about
energy distribution in the system, so one doesn't drive the other.
You don't lose heat to "drive the reactions fast" either. While one can
speed up a reaction with heat, it works fairly slowly. Twice faster for
every 10 degrees (iirc), by which time a human would be well done, so my
guess is that we lose heat to actually prevent this scenario, not to
drive our reactions really fast (though one could argue, that we already
do by walking so close to the temperature of cooking proteins).

--
Andrzej Rosa 1127R
.

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