BIOL373 Chapter : Unit 6 - Digestive System - Full Textbook Notes
5 Sep 2013
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Document Summary
The gastrointestinal tract (gi tract) is a long tube passing through the body: the lumen and its contents are actually part of the external environment. The primary function of the gi tract is to move nutrients, water, and electrolytes from the external environment into the body"s internal environment. Peptic ulcers are raw patches on the walls of the gi tract due to the failure of protective mechanisms against autodigestion. The body naturally excretes more fluid than it intakes; therefore, fluid must be reabsorbed or the body would rapidly dehydrate. The digestive tract must also repel foreign invaders; defense mechanisms include: mucus, digestive enzymes, acid, and the largest collection of lymphoid tissue in the body, the gut-associated lymphoid tissue (galt) Evidence shows that changing long-term environmental conditions, effects nutrient absorption: motility: movement of material in the gi tract as a result of muscle contraction.
