BIO 203 Lecture Notes - Lecture 1: Feces, Rugae, Gastric Glands
10 Aug 2016
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Document Summary
Gastrointestinal tract (gi tract) is a long tube passing through the body; the tube has muscular walls lined with epithelium and closed off by skeletal muscle sphincter at each end. Primary fxn is to move nutrients, water, and electrolytes from external environment into internal environment. Enzymes that digest food must not digest cells (autodigestion) Digestive system (ds) must match fluid input with output. Ds must be efficient in repelling foreign invaders. Must absorb water/nutrients while keepings pathogens from entering. Transporting epithelium of gi is assisted with defense mechanisms, such as music, enzymes, acids, and gut associated lymphoid tissue (galt) Secretion, transepithelial transfer of water and ions from ecf to digestive tract lumen and releasing substances synthesized by gi epithelial cells. Motility is regulated b/c if food moves too rapidly, there is not enough time for everything in lumen to be digested and absorbed.
