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Unformatted text preview: Endocrine System Action of Water-soluble Hormone * Binds at the membrane receptor (first messenger) * A second messenger is released within the cell where hormone-stimulated responses can take place * One common second messenger is cylic AMP (cAMP), which is synthesized from ATP * G-protein- link receptors on the outer surface of the membrane to the adenylate cyclase on the inner surface * The binding of a hormone to its receptor activates many G-protein molecules, which in turn activate molecules of adenylate cyclase. * Unless activated by more hormone, G-protein slowly deactivates, thus stopping hormone response Clinical Application Cholera Toxin and G Protein * Cholera toxin produces massive watery diarrhea in which a person can rapidly die of dehydration * Toxin modifies G protein in the intestinal epithelial cells such that they become locked in an activated state. * Results in large intracellular concentration of cAMP * Effect is to stimulate an active transport pump that ejects chloride inos from the cells into...
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This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.
- Fall '10