Ask A Scientist© Zoology Archive

name         Sheule B.
status       student
age          18
Question -   How does osmoregulation take place in the kidneys?
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This is one of the most demanding questions a physiologist can field.  The
methods that cortical and medullary nephrons accomplish this is dependent on
an extremely complex architecture that coincides with a more complex
physiochemical set of
Processes...I suggest you consult a good physiology text...Human
Physiology..Rhodes and Flanders is oK or a copy of Medical Physiology by
Guyton...excellent text....good luck...you will need it...:)


Peter Faletra Ph.D.
Office of Science
Department of Energy
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This is actually quite a complicated question-it would take up a whole
chapter in an anatomy and physiology text. Basically, the permeability
(leakiness) kidney tubules can be controlled. There are feedback systems
that determine when the body needs to retain water or lose water and these
signals are sent by hormones from the brain. If you look at a diagram of a
nephron (the functional unit of the kidney-there are millions of them) there
is a structure called the Loop of Henle. The tissue around the loop has a
gradient of "saltiness" (not really salt but for comparison to osmosis). As
the loop descends the tissue around it becomes more and more "salty". It
then rises again and it becomes less salty again. When the body needs to
lose water, the tubules are not permeable, in other words, the water cannot
leave the tubules and goes out to the ureters and to the bladder. If the
body needs water, the hormones make the tubules become permeable and the
"saltiness" of the tissues causes the water to leave the tubules. Obviously,
this is a simple answer to a complicated question and I would refer you to
any anatomy/physiology text for a more complete answer.

vanhoeck
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