BIOL 1080 Lecture Notes - Lecture 14: Bifidobacterium, Bile Acid, Transport Protein
6 Dec 2017
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Document Summary
The gi tract represents a vast surface area of the body that is exposed to the external environment. It not only sees our food, but potentially toxic substances and infectious agents. Mechanisms unique to this system deal with: sense and expel noxious substances- vomit, diarrhea, specialized populations of t cells localized to the intestinal mucosa ex. Oral cavity, upper esophageal sphincter, esophagus, lower esophageal sphincter, stomach, pyloric sphincter, small intestine, ileocecal valve, colon (large intestine), anal sphincter, rectum. Tract must be controlled, work with nervous system. Many systems to protect from noxious substances that could get in. Has its own special immune system (peyer"s patches) About 28 ft. long, has to be folded extensively in the abdominal cavity. Has a large luminal surface area of 200-400 square meters due to villi/ microvilli. Highly variable transit time for an ingested meal with a marker (30-80 hours) Spends 5-8 hours in the stomach and the small intestine, the rest in the colon.
