An examination of the various mechanisms in the gastrointestinal tract that allow to be ingested, digested, absorbed, and then its residue to be excreted reveals the complexity of the digestion/absorption process. Normal digestion and absorption of nutrients is dependent not only on a healthy alimentary canal but also on an exquisite integration of the digestive system with the nervous system, endocrine system, and circulatory system. An excellent example of this integration of systems is the finely controlled emptying of chyme from the stomach into the small intestine.
The many factors influencing digestion and absorption, including the dispersion and mixing of ingested food, the quantity and composition of gastrointestinal secretions, status of the enterocytes, expanse of intestinal absorptive area and the transit time of intestinal contents must be coordinated so that nourishment of the body can occur while homeostasis of body fluids is maintained. Much of the coordination required is provided by regulatory peptides, some of which are provided by the nervous system as well as by the endocrine cells of the gastrointestinal tract.
How Gastrointestinal Tract Function?
