Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture prepared by Kathleen A. Ireland, Seabury Hall, Maui, Hawaii Anatomy & Physiology M A R T I N I FIRST EDITION C h a p t e r 24 The Digestive System PowerPoint® Lecture Slides prepared by Jason LaPres Lone Star College - North Harris Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The muscular digestive tract Various accessory organs The Digestive system includes:
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.1 Figure 22.1 The Components of the Digestive System
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Ingestion Mechanical processing Digestion Secretion Absorption Excretion Functions of the digestive system
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Mesenteries Sheets of serous membranes that support portions of the digestive tract Greater omentum lies anterior to abdominal viscera Provides padding, protection, insulation, and energy reserves Lesser omentum The digestive system organs and the peritoneum
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.2 Mesenteries Figure 22.2a
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.2 Mesenteries Figure 22.2b
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.2 Mesenteries Figure 22.2c
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.2 Mesenteries Figure 22.2d
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Mucosa lines digestive tract (mucous epithelium) Moistened by glandular secretions Lamina propria and epithelium form mucosa Submucosa Layer of dense irregular connective tissue Histological organization of the digestive tract
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscularis externa Smooth muscle arranged in circular and longitudinal layers Adventitia Serosa Serous membrane covering most of the muscularis externa Histological organization of the digestive tract
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.3 The Structure of the Digestive Tract Figure 22.3
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Visceral smooth muscle shows rhythmic cycles of activity Pacemaker cells Peristalsis Waves that move a bolus Segmentation Churn and fragment a bolus Movement of digestive materials
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.4 Peristalsis Figure 22.4
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Movement of materials along the digestive tract is controlled by: Neural mechanisms Parasympathetic and local reflexes Hormonal mechanisms Enhance or inhibit smooth muscle contraction Local mechanisms Coordinate response to changes in pH or chemical stimuli Control of the digestive system
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.5 The Regulation of Digestive Activities Figure 22.5
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Its functions include: Analysis of material before swallowing Mechanical processing by the teeth, tongue, and palatal surfaces Lubrication Limited digestion The mouth opens into the oral or buccal cavity
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Lined by oral mucosa Roof of cavity = hard and soft palates Floor of cavity = tongue Uvula guards opening to pharynx Oral cavity
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.6 The Oral Cavity Figure 22.6a, b
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Primary functions include: Mechanical processing Assistance in chewing and swallowing Sensory analysis by touch, temperature, and taste receptors The tongue
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Extrinsic and intrinsic tongue muscles Innervated by the hypoglossal nerve Tongue movements involve
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Parotid, sublingual, and submandibular Saliva Watery solution Electrolytes, buffers, glycoproteins, antibodies, enzymes Functions include: Lubrication, moistening, and dissolving Initiation of digestion of complex carbohydrates Salivary glands (three pairs)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.7 The Salivary Glands Figure 22.7a, b
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Function in mastication of bolus Contact of occlusal surfaces Contain three layers Enamel covering crown Dentin forms basic structure Root coated with cementum Periodontal ligaments hold teeth in alveoli Teeth
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 20 primary teeth AKA deciduous teeth 32 teeth of secondary dentition Eruption of teeth
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.8 Teeth Figure 22.8a, b
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.9 Primary and Secondary Teeth Figure 22.9a, b
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Common passageway for food, liquids, and air Lined with stratified squamous epithelium Pharyngeal muscles assist in swallowing Pharyngeal constrictor muscles Palatal muscles The pharynx
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Carries solids and liquids from the pharynx to the stomach Passes through esophageal hiatus in diaphragm The wall of the esophagus contains mucosal, submucosal, and muscularis layers The esophagus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Distinctive features of the esophageal wall include Nonkeratinized, stratified squamous epithelium Folded mucosa and submucosa Mucous secretions by esophageal glands A muscularis with both smooth and skeletal muscle portions Lacks serosa Anchored by an adventitia Histology of the esophagus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure The Esophagus Figure 22.10
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Buccal phase Pharyngeal phase Esophageal phase Swallowing (deglutition)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure The Swallowing Process Figure 22.11a-h
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Bulk storage of undigested food Mechanical breakdown of food Disruption of chemical bonds via acids and enzymes Production of intrinsic factor Functions of the stomach
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cardia – superior, medial portion Fundus – portion superior to stomach-esophageal junction Body – area between the fundus and the curve of the J Pylorus – antrum and pyloric canal adjacent to the duodenum Anatomy of the stomach
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Phloric Sphincter Guards exit from stomach Rugae Ridges and folds in relaxed stomach Stomach anatomy
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure The Stomach Figure 22.12b
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Gastric glands Parietal cells Intrinsic factor, and HCl Chief cells Pepsinogen Pyloric glands Mucous secretion containing several hormones Enteroendocrine cells G cells secrete gastrin D cells secrete somatostatin Histology of the stomach
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure The Stomach Lining Figure 22.13
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure The Secretions of Hydrochloric Acid
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cephalic phase prepares stomach to receive ingested material Gastric phase begins with the arrival of food in the stomach Neural, hormonal, and local responses Intestinal phase controls the rate of gastric emptying Regulation of gastric activity
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.15a Figure The Phases of Gastric Secretion
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.15b Figure The Phases of Gastric Secretion
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.15c Figure The Phases of Gastric Secretion
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Preliminary digestion of proteins Pepsin Permits digestion of carbohydrates Very little absorption of nutrients Some drugs, however, are absorbed Digestion and absorption in the stomach
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Important digestive and absorptive functions Secretions and buffers provided by pancreas, liver, gall bladder Three subdivisions: Duodenum Jejunum Ileum Ileocecal sphincter Transition between small and large intestine Small intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.16a Figure Regions of the Small Intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Plicae Transverse folds of the intestinal lining Villi Fingerlike projections of the mucosa Lacteals Terminal lymphatic in villus Intestinal glands Lined by enteroendocrine, goblet and stem cells Histology of the small intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.17a Figure The Intestinal Wall
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.17b, c Figure The Intestinal Wall
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.17d, e Figure The Intestinal Wall
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Moisten chyme Help buffer acids Maintain digestive material in solution Intestinal juices
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Duodenal glands (Brunner’s glands) Produce mucus, buffers, urogastrone Ileum Aggregated lymphoid nodules (Peyer’s patches) Small Intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Peristalsis Segmentation Gastroenteric reflexes Initiated by stretch receptors in stomach Gastroileal reflex Triggers relaxation of ileocecal valve Intestinal movements
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Pancreatic duct penetrates duodenal wall Endocrine functions Insulin and glucagons Exocrine functions Majority of pancreatic secretions Pancreatic juice secreted into small intestine Carbohydrases Lipases Nucleases Proteolytic enzymes The pancreas
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.18a-c Figure The Pancreas
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Performs metabolic and hematological regulation and produces bile Histological organization Lobules containing single-cell thick plates of hepatocytes Lobules unite to form common hepatic duct Duct meets cystic duct to form common bile duct The liver
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure The Anatomy of the Liver
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Liver lobule is the basic functional unit of the liver Hepatocytes form irregular plates arranged in spoke-like fashion Bile canaliculi carry bile to bile ductules Bile ductules lead to portal areas
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.20a, b Figure Liver Histology
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Hollow, pear-shaped organ Stores, modifies and concentrates bile The gallbladder
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.21a, b Figure The Gallbladder
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neural and hormonal mechanisms coordinate glands GI activity stimulated by parasympathetic innervation Inhibited by sympathetic innervation Enterogastric, gastroenteric and gastroileal reflexes coordinate stomach and intestines Coordination secretion and absorption
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reabsorb water and compact material into feces Absorb vitamins produced by bacteria Store fecal matter prior to defecation Functions of the large intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Ascending Transverse Descending Sigmoid The four areas of the colon are:
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.22a Figure The Large Intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 22.22b, c Figure The Large Intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Last portion of the digestive tract Terminates at the anal canal Internal and external anal sphincters The rectum
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Absence of villi Presence of goblet cells Deep intestinal glands Histology of the large intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reabsorption in the large intestine includes: Water Vitamins – K, biotin, and B 5 Organic wastes – urobilinogens and sterobilinogens Bile salts Toxins Mass movements of material through colon and rectum Defecation reflex triggered by distention of rectal walls Physiology of the large intestine
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure The Defecation Reflex
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Disassembles organic food into smaller fragments Hydrolyzes carbohydrates, proteins, lipids and nucleic acids for absorption Processing and absorption of nutrients
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Begins in the mouth Salivary and pancreatic enzymes Disaccharides and trisaccharides Brush border enzymes Monosaccharides Absorption of monosaccharides occurs across the intestinal epithelia Carbohydrate digestion and absorption
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Lipid digestion utilizes lingual and pancreatic lipases Bile salts improve chemical digestion by emulsifying lipid drops Lipid-bile salt complexes called micelles are formed Micelles diffuse into intestinal epithelia which release lipids into the blood as chylomicrons Lipid digestion and absorption
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Low pH destroys tertiary and quaternary structure Enzymes used include pepsin, trypsin, chymotrypsin, and elastase Liberated amino acids are absorbed Protein digestion and absorption
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Water Nearly all that is ingested is reabsorbed via osmosis Ions Absorbed via diffusion, cotransport, and active transport Vitamins Water soluble vitamins are absorbed by diffusion Fat soluble vitamins are absorbed as part of micelles Vitamin B 12 requires intrinsic factor Absorption
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The organs of the digestive system and their major functions The mechanisms that regulate digestion The anatomy of the organs and accessory organs of the digestive system You should now be familiar with:
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings The functions of the major structures and regions of the digestive system and the regulation of their activities The significance of the large intestine in the absorption of nutrients The events involved in the digestion of organic and inorganic nutrients You should now be familiar with: