Physiology 3120 Lecture Notes - Lecture 12: Phosphatase, Sucrase, Amylase
11 Aug 2016
School
Department
Course
Professor
Document Summary
Secretions from pancreas and liver and bile from gall bladder empties into duodenum. Hormones released by duodenal endocrine cells regulate speed of digestion/absorption. Jejunum has many absorptive enterocytes with long villi that further amplifies absorption. Only absorbs nutrients if issues prevented it in earlier sections. Crypts are invaginations into mucosa that contain stem cells to regenerate enterocytes on surface. Mucus secreted in small intestine protects cells but this time from constant vigorous motion of chyme passing through: lysozymes break down bacterial cell walls, secretin is stimulated by stomach acid remaining in chyme that gets to small intestine. These stem cells have high turnover which makes stomach/intestine more susceptible to cancer. Leaky epithelium of small intestine allow paracellular transport of nutrients and water into cells. Tight epithelium of stomach prevent paracellular transport of acids and microbes into cells. Jejunum has most and longest villi and those villi have mv.
