BIOL 121 Lecture Notes - Lecture 30: Common Bile Duct, Gastrointestinal Tract, Intestinal Gland
Document Summary
Jejunum: many villi to increase surface area for maximum absorption analogy of bed sheets vs. bath towel, most nutrient absorption here. Ileum: backup system for absorption, less villi but can still absorb nutrients if necessary. Layers of the small intestine: mucosa innermost layer, villi finger like projections, single layer of epithelial cells which produce different things. Submucosa: sticks muscle layer to mucosa, submucosa plexus, muscularis, smooth muscle, circular and longitudinal, mechanical breakdown, myenteric plexus neuron group to control muscles. Serosa outermost layer: dense connective tissue, holds everything together. Segmentation: specialized, localized mixing contractions to mix chyme with digestive juices & increase interactions of chyme with absorptive cells in the intestinal mucosa. Peristalsis: unidirectional movement where chyme is propelled forwards to the next portion of the small intestine after thorough segmentation. Cells of the intestine wall: absorptive cells epithelial cells with microvilli (exocrine) Increase surface area: goblet cells (exocrine, secretes mucus - reduces friction.
