ZOO 3000 Lecture Notes - Lecture 13: Taenia Coli, Stomach, Jejunum
27 Jul 2018
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Longest portion of digestive tract - ~6m in humans: divided into 3 regions, duodenum. In most mammals, the small intestine is not separated into 3 regions. Functions: transport food in one direction, complete digestion, absorb final digestion products, secretion of hormones. Immunological protection (barriers: most absorption occurs in the small intestine making it the easiest spot for pathogens to enter the body. Surface specialized for functions: plicae circulares circular folds, vili, microvilli, glands in mucosa and submucosa. Intesticnal glands in mucosa participates in absorption: brunner"s glands in submucosa of the duodenum highly alkaline secretion participates in stomach acid neutralization. Enterocytes or columnar absorptive cells: shape columnar, found throughout epithelium, nucleus ovoid, basal, apical surface (cid:862)(cid:271)rush(cid:863) (cid:271)order (microvilli), terminal bars with tight junctions, function, microvilli increase absorptive surface up to 600 times. Enterocytes are involved in ion, water, sugar, amino acid and lipid uptake: mucous goblet cells, shape goblet-like nucleus ovoid to spherical, basal, cytoplasm filled with mucinogen, function:
