Example

One example of the consequences of uncontrolled ions movements is when the bacterium, Vibrio cholerae releases its toxin in the large intestine. The protein binds to and opens a chloride ion channels on the epithelium surface. Chloride ions flood out into the lumen lowering water potential causing rapid loss of water, chronic diarrhoea and severe dehydration. In the absence of the toxin these ions would have remained inside the epithelial cells. Water alone cannot be used to rehydrate the sufferer as it cannot easily be absorbed through the intestinal epithelium. The reabsorption of water requires sodium and glucose, two key components of oral rehydration solutions. These species are taken up by co-transport in the small intestine region of the digestive system which lowers water potential sufficiently to allow the absorption of water and the rehydration of the sufferer.