Nutrition and the Gastrointestinal Tract

Authored by: Harry L. Greene

Handbook of Nutrition and Food

Print publication date:  July  2013
Online publication date:  April  2016

Print ISBN: 9781466505711
eBook ISBN: 9781466505728
Adobe ISBN:


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No organ is more essential to the maintenance of adequate nutrition than the gastrointestinal (GI) tract. The lining of the GI tract consists of a single layer of highly specialized columnar epithelial cells that interface between the external and internal environments. Its primary function is the transfer of dietary constituents from the bowel lumen into the circulation. Consequently, the GI tract must convert the varied physical and chemical forms of food into simple molecules that can be easily transferred across cell membranes. This process requires coordinated motor activity and secretion of digestive enzymes that alter chemical properties of food. Subsequently, intact transport mechanisms across cell membranes are necessary to accomplish the final transfer of vital nutrients into the blood or lymphatics. Finally, assimilation of essential nutrients must be done from food sources alien, and often hostile, to the body. Failure of any of these processes can result in malabsorption, immune dysfunction, or bacterial invasion.

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