physiology hw 1

physiology hw 1 - Physiology 42-202 1/23/2008 1. The...

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Physiology 42-202 1/23/2008 1. The Cholera toxin consists of two parts: an enzyme that disrupts the salt and water balance, and a hormone that fools the cell into receiving the toxin. This toxin stimulates the second messenger, cAMP by binding to epithelial cell membranes and releasing an enzyme that increases cAMP production. An increase in cAMP production causes a secretion of electrolytes, and water following the electrolytes. Chloride is actively transported out of the cell, and this creates a negative electric potential outside, which causes an outflow of positive sodium ions. As a result of osmosis, water also follows the ions and passively moves down the gradient, outside the cell. This secretion of sodium ions, chloride ions, and water results in diarrhea because of the amount of water that flows into the colonic lumen. The person will eventually die of dehydration if the subject does not receive rehydration treatment in time. (This time period usually ranges from 18 hours to several days.)
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This note was uploaded on 03/30/2010 for the course BIO 42202 taught by Professor Sanders during the Spring '10 term at Carnegie Mellon.

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physiology hw 1 - Physiology 42-202 1/23/2008 1. The...

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