living systems and 2nd law of thermo??????

simon sbe at biochem.usyd.edu.au
Tue Sep 26 02:18:41 EST 1995


rray at ix.netcom.com (ROMAN RAY ) wrote:
>  Living sytems have order.  Why does this not violate the second law
>of thermodynamics?????


It does not violate the second law - this law only applies to *isolated* 
systems - those which can not exchange heat or matter with their 
surroundings. Living cells/organisms are *open* sytems because they 
exchange both heat and matter (nutrients/excreta) with their 
surroundings.

If you do the measurements/calculations on a living system *plus* its 
surroundings, then any decrease in the entropy of the living system (an 
increase in its "order") is more than balanced by an increase of the 
entropy of the surroundings.

Simon





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