After appropriate digestion of nutrients, the function of the gastrointestinal tract is to absorb these nutrients so they may be used for a variety of cellular processes.

Absorption occurs across the cells lining the small intestine and proceeds via one of several mechanisms. The first is passive absorption, in which material moves along an electrochemical gradient. The second is facilitated transport, in which absorption of one substance is coupled to the transfer of another substance. (more…)

The regulation of fluid balance is crucial to survival. Approximately 9 L of fluid enters the gastrointestinal tract per day. Of that amount, about 2 L is ingested by mouth. The remaining 7 L consists of fluids secreted by the various gastrointestinal organs. Ninety eight percent of the total amount of fluid that enters the gastrointestinal tract is reabsorbed in the small intestine and the colon. (more…)

The motility of the gastrointestinal tract is complex, and normal motility is critical to proper secretion and digestion. In order for gastrointestinal motility to be effective, it must be coordinated with other intestinal functions such as secretion and absorption, and it must be regulated and integrated in a precise fashion. (more…)