Patient admitted to the hospital with severe diarrhea is dia

Patient admitted to the hospital with severe diarrhea is diagnosed with cholera. What causes it and what does the causative agent do that makes us lose SO much fluid SO fast with this disease? .... Please explain in detail. Thank you!

Solution

Cholera is caused by Vibrio cholerae which produces cholera toxin. This cholera toxin binds to receptors in the wall of upper small intestine and activates adenylyl cyclase enzyme. This enzyme produces cAMP. The increased cAMP levels leads to opening of chloride channel in intestinal wall which in turn prevents NaCl absorption by ATP-dependent active sodium absorption pump. This pump is present on basolateral membranes of crypts of intestine and villus tip cells. The disturbed NaCl absorption leads to build up of water and causes watery diarrhea.