Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Tenth Edition Shier w Butler w Lewis Chapter 17 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Chapter 17 Digestive System Functions of Digestive System • ingestion • mechanical digestion • chemical digestion • propulsion • absorption • defecation 2 Major Organs 3 Alimentary Canal 4 Alimentary Canal Wall 5 Movements of the Tube • mixing movements • peristalsis 6 Innervation of the Tube • submucosal plexus – controls secretions • myenteric plexus – controls gastrointestinal motility • parasympathetic impulses – increase activities of digestive system • sympathetic impulses – inhibit certain digestive actions 7 Mouth • ingestion • mechanical digestion • prepares food for chemical digestion 8 Tongue 9 Palate • roof of oral cavity 10 Primary Teeth • 8 incisors • 4 cuspids • 8 molars 11 Secondary Teeth 12 Section of a Tooth 13 Salivary Glands 14 Secretions of Salivary Glands • Parotid glands • clear • water, serous fluid • rich in amylase • Sublingual glands • primarily mucus • most viscous • Submandibular glands • primarily serous fluid • some mucus 15 Pharynx 16 Swallowing Mechanism • soft palate and uvula raise • hyoid bone and larynx elevate • epiglottis closes off top of trachea • longitudinal muscles of pharynx contract • inferior constrictor muscles relax and esophagus opens • peristaltic waves push food through pharynx 17 Swallowing Mechanism 18 Esophagus 19 Stomach 20 Radiograph of Stomach 21 Lining of Stomach 22 Gastric Secretions • pepsinogen • from chief cells • inactive form of pepsin • pepsin • from pepsinogen in presence of HCl • protein splitting enzyme • hydrochloric acid • from parietal cells • needed to convert pepsinogen to pepsin • mucus • from goblet cells and mucous glands • protective to stomach wall • intrinsic factor • from parietal cells • required for vitamin B12 absorption 23 Phases of Gastric Secretion • Cephalic phase • triggered by smell, taste, sight, or thought of food • parasympathetic impulses trigger gastric juice secretion • Gastric phase • triggered by presence of food in stomach • gastrin released • gastric juice secreted • Intestinal phase • triggered by movement of food into small intestine • intestinal cells release intestinal gastrin • secretion of gastric juice 24 Regulation of Gastric Secretions 25 Gastric Absorption • some water • certain salts • certain lipid-soluble drugs • alcohol 26 Mixing and Emptying Actions 27 Enterogastric Reflex regulates the rate at which chyme leaves the stomach 28 Pancreas 29 Pancreatic Juice • pancreatic amylase – splits glycogen into disaccharides • pancreatic lipase – breaks down triglycerides • trypsin, chymotrypsin, and carboxypeptidase – digest proteins • nucleases – digest nucleic acids • bicarbonate ions – make pancreatic juice alkaline 30 Regulation of Pancreatic Secretions • acidic chyme stimulates release of secretin • secretin stimulate release of pancreatic juice 31 Liver 32 Hepatic Lobule 33 The Paths of Blood and Bile in Hepatic Lobule 34 Liver Functions • produces glycogen from glucose • breaks down glycogen into glucose • converts noncarbohydrates to glucose • oxidizes fatty acids • synthesizes lipoproteins, phospholipids, and cholesterol • converts carbohydrates and proteins into fats • deaminates amino acids • forms urea • synthesizes plasma proteins • converts some amino acids to other amino acids • stores glycogen, vitamins A,D, B12, iron, and blood • phagocytosis of worn out RBCs and foreign substances • removes toxins from blood • produces and secretes 35 Composition of Bile • water • bile salts • emulsification of fats • absorption of fatty acids, cholesterol, and fat-soluble vitamins • bile pigments • cholesterol • electrolytes 36 Gallbladder 37 Regulation of Bile Release • fatty chyme entering duodenum stimulate gallbladder to release bile 38 Three Parts of Small Intestine 39 Mesentery • suspends portions of the small intestine from the posterior abdominal wall 40 Intestinal Villus 41 Intestinal Epithelium 42 Wall of Small Intestine 43 Secretions of Small Intestine • peptidase – breaks down peptides into amino acids • sucrase, maltase, lactase – break down disaccharides into monosaccharides • lipase – breaks down fats into fatty acids and glycerol • enterokinase – converts trypsinogen to trypsin • somatostatin – hormone that inhibits acid secretion by stomach • cholecystokinin – hormone that inhibits gastric glands, stimulates pancreas to release enzymes in pancreatic juice, stimulates gallbladder to release bile • secretin – stimulates pancreas to release bicarbonate ions in pancreatic juice 44 Regulation of Small Intestinal Secretions • mucus secretion stimulated by presence of chyme in small intestine • distension of intestinal wall activates nerve plexuses in wall of small intestine • parasympathetics trigger release of intestinal enzymes 45 Absorption in the Small Intestine • monosaccharides and amino acids • through facilitated diffusion and active transport • absorbed into blood • electrolytes and water • through diffusion, osmosis, and active transport • absorbed into blood 46 Absorption in the Small Intestine • fatty acids and glycerol • several steps • absorbed into lymph and blood 47 Movements of the Small Intestine • mixing movements • peristalsis – pushing movements • segmentation – ringlike contractions • overdistended wall triggers peristaltic rush resulting in diarrhea 48 Large Intestine 49 Large Intestinal Wall 50 Functions of Large Intestine • little or no digestive function • absorbs water and electrolytes • secretes mucus • houses intestinal flora • forms feces • carries out defecation 51 Movements of Large Intestine • slower and less frequent than those of small intestine • mixing movements • peristalsis • mass movements usually follow meals 52 Feces • water • electrolytes • mucus • bacteria • bile pigments altered by bacteria provide color • smell produced by bacterial compounds 53 Life-Span Changes • teeth become sensitive • gums recede • teeth may loosen or fall out • heartburn more frequent • constipation more frequent • nutrient absorption decreases • accessory organs age but the effects are less noticeable 54 Clinical Application Hepatitis • inflammation of the liver • most commonly caused by viral infection • can be caused by reactions to drug, alcoholism or autoimmunity Signs and Symptoms • headache • low fever • fatigue • vomiting • rash • foamy urine • pale feces • jaundice • pain Hepatitis A – not washing hands or eating raw shellfish Hepatitis B – chronic; serum Hepatitis C – serum Hepatitis D – very severe; only produces symptoms if infected with B; serum Hepatitis E, F, G – more rare 55