Diarrhea

Diarrhea (AmE) or diarrhoea (CwE) is a condition in which the sufferer has frequent and watery or loose bowel movements (from the ancient Greek word ??????? = leakage; lit. "to run through"). In the Third World, diarrhea is the most common cause of death among infants, killing more than 1.5 million per year.

Mechanism

To evacuate the contents of the lower digestive tract, the fluidity of the contents of the small and large intestines is increased. Active transport of Na+ back into the gut intiates a reverse sodium transport. This causes both Cl- and HCO3 to follow passively, as well as water. Now in the intestines, the water dilutes toxins as well as triggers contractions of the intestine due to increase in intestinal distension. These contractions push the contents of the lower GI tract towards and out of the anal canal. Medications such as loperamide are designed to prevent such contractions in response to the distension, and should not be used to prevent diarrhea. Such inhibition actually prolongs the infection or irritation, and can cause a worsening over time because the evacuation of the bowel contents has been delayed.

Related Topics:
Active transport - Cl^- - HCO₃ - Medication - Loperamide

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