PHIS 206 1st Edition Lecture 25 Outline of Last Lecture I Review Terms Outline of Current Lecture I GI Tract and Homeostasis II Anatomy III Function of the Digestive System IV Wall of the GI Tube V Differences in the Gut Wall VI Hepatic Portal System VII Motility VIII Secretion IX Digestion X Absorption XI Regulation Stimuli XII Stimuli Receptors Current Lecture I GI Tract and Homeostasis help transfer sources of energy nutrients water electrolytes into the body nutrients used to create energy for the body to use These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute body does not change its absorptive capacity if you increase intake no effect on what gets absorbed body will take the nutrients it need despite how much you put in GI tract is mainly smooth muscle Interstitial Cells of Cajal cells that generate slow waves II Anatomy Tract mouth pharynx esophagus Accessory Organs stomach small intestine large intestine colon cecum rectum anus Accessory Glands sublingual under tongue submandibular under jaw salivary glands parotid salivary gland liver gallbladder pancreas III Function of the Digestive System Four Processes to Digest food and Absorb Nutrients into the Blood 1 Motility 2 Secretion 3 Digestion 4 Absorption IV Wall of the GI Tube mucosa absorption and secretion of fluids villa increases surface area of mucosa finger like structure submucosa small blood vessels connective tissue houses vessels muscularis externa outer longitudinal muscle shorten length of whole tube inner circular muscle gets food inside body to outside body myenteric plexus control of muscular system nerve network submucosal plexus in submucosa nerve network serosa pushing on other parts lubrication V Differences in the Gut Wall Different tubes specialize in different tasks stomach has extra muscle layer colon flat not much reabsorption VI Hepatic Portal System helps with motility liver processes stores and detoxifies modifies ingested drugs Tylenol scenario not good because stuff is stored in liver VII Motility Regulated process movement and mixing off contents through muscular contractions 2 types propulsive peristaltic o moves food through GI tract different parts have different rates mixing segmentation o food mixed with digestive juice and helps absorption VIII Secretion release of water electrolytes enzymes and mucus into the gut Endocrine internal in the wall of lumen goblet cells Exocrine external glands organs pancreas liver salivary IX Digestion the chemical and mechanical breakdown of ingested material into absorbable molecules glucose enzymes usually do this but gastric acids help digestion is NOT regulated but secretion IS regulated X Absorption movement of products gut lumen mucosa of the gut wall into the BLOOD NOT directly regulated XI Regulation Stimuli Luminal stimuli distention of gut wall chyme osmolarity solute concentration chyme acidity specific digestive products in the chyme Brain CNS sight thought smell of food Ex t v commercials may affect emotional state XII Stimuli Chemical molecules Pressure stretch brush Osmolarity concentration Receptors Chemoreceptors Mechanoreceptors Osmoreceptors
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