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Saturday, December 4, 2010

CELLULAR DEHYDRATION

CELLULAR DEHYDRATION
When our bodies lose too much water, or we eat foods rich in salt, we feel thirsty, apparently because of cellular dehydration, leading to cell shrinkage. For instance, if concentrated sodium chloride solution is administered, this leads to withdrawal of water from the cells of the body by osmosis, and results in drinking. Cellular dehydration is sensed centrally in the brain, rather than peripherally in the body. For instance, low doses of hypertonic sodium chloride (or sucrose) solution infused into the carotid arteries, which supply the brain, cause dogs to drink water, but similar infusions administered into peripheral regions of the body, which don’t directly supply the brain, have no effect (Wood et al., 1977).

The part of the brain that senses cellular dehydration appears to be near or in a region extending from the preoptic area through the hypothalamus.

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