PHSI 208 Lecture Notes - Lecture 51: Migrating Motor Complex, Myosin Light-Chain Kinase, Immunoglobulin Light Chain
Document Summary
Has two purposes: moves food from mouth to anus, mechanically mixing food breaks it into uniformly small particles. Gi motility determined by properties of smooth muscle and modified by chemical input from nerves, hormones and paracrine signals: the muscles are single-unit smooth muscles that are connected by gap junctions. There are 2 different patterns of contraction that can occur: Tonic smooth muscles usually contracted at all time; relaxes to allow materials to pass. Phasic smooth muscle cycles b/w contraction and relaxation: posterior region of stomach and small intestines. *motility and secretion are the primary regulated functions in the gi system. Neural regulation submucosal and myenteric plexuses form the ens (100-500 m neurons: neurons synapse w/ each other, smooth muscles, glands and epithelial cells, short reflexes integrated entirely within the ens, long reflexes integrated within the cns. Regulation through gi peptides hormones, neuropeptides and cytokines. Neurotransmitters and neuromodulators: ~30 neurotransmitters, many identical to cns (serotonin, ach, vip, no)
