The Human Body in Health and Illness, 4 th edition Barbara Herlihy Chapter 23: Digestive System 1 Lesson 23-1 Objectives List four functions of the digestive system. Describe the four layers of the digestive tract. Describe the structure and functions of the organs of the digestive tract. Describe the structure and functions of the accessory organs of the digestive tract.http://www.youtube.com/watch?v=SyVc yT-fOao&feature=relatedhttp://www.youtube.com/watch?v=SyVc yT-fOao&feature=related Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 2 Functions of the Digestive System Ingest food Digest it Mechanical Chemical Absorb nutrients Excrete wastehttp://www.yo utube.com/watch?v =Z7xKYNz9AS0http://www.yo utube.com/watch?v =Z7xKYNz9AS0 Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 3 Overview of the Digestive System Mouth Pharynx Esophagus Stomach Small intestine Large intestine Rectum, anus Accessory organs Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 4 Four Layers of the Digestive Tract Mucosal layer Submucosal layer Muscle layer - Circular and longitudinal - Mixing, mashing action - Peristaltic action - Enteral nervous system Serosal layer - Peritoneal membranes Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 5 Peristalsis Waves of muscle contraction, relaxation Pushes food from mouth toward anus Peristaltic movements differ from organ to organ Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 6 Oral Cavity Teeth: Mastication Tongue: Swallowing Salivary glands - Parotid - Submandibular - Sublingua l Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 7 Eating and Swallowing Mouth Pharynx Esophagus - Esophageal sphincters Pharyngoesophageal Lower esophageal Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 8 Salivary glands Three pairs of salivary glands 1) Parotid glands 2) submandibular glands 3) sublingual glands Epiglottis-Ps&feature=relatedPs&feature=related Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 9 Functions of the Stomach Regulates rate of gastric emptying Secretes gastric juice, including HCl Secretes gastric hormones and intrinsic factor Digests limited amount of food Absorbs limited substances Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 10 Parts of the Stomach Fundus Body Pylorus Pyloric sphincter Lesser curvature Greater curvature Rugae Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 11 Muscles of the Stomach Longitudinal Oblique Circular Mixing and mashing chyme Peristalsis Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 12 Stomach Structure: Mucosa Mucous cells Parietal cells - HCl - Intrinsic factor Chief cells - Digestive enzymeshealth/health- topics/topics/prnanmia/ Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 13 Clinical Conditions: Stomach Gastric ulcer Hiatal hernia Nasogastric tube Gastrostomy tube Gastric resection Pyloric stenosis Vagolytic effects Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 14 Small Intestine: Parts and Functions Parts Duodenum Jejunum Ileum Functions Digests Absorbs Secretes hormones and digestive enzymes Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 15 Duodenum: Villi and Microvilli Folds increase area for absorption Inside composed of capillaries and lacteals End products of digestion delivered to hepatic portal system and lymphatics Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 16 Large Intestine Cecum Vermiform appendix Colon Ascending Transverse Descending Sigmoid Rectum and anus Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 17 Functions of the Large Intestine Absorption of water and electrolytes Synthesis of vitamins by intestinal bacteria Temporary storage of waste Elimination of waste (feces) and gas (flatus) Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 18 Clinical Conditions: Large Intestine Intestinal obstruction Colostomy Hemorrhoids Enema Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 19 Accessory Digestive Organs Liver Gallbladder Pancreas Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 20 Liver Functions Synthesis of bile salts and secretion of bile Synthesis of plasma proteins Storage of glucose, fat-soluble vitamins Detoxification Main organ for drug detoxification Excretion of bilirubin, cholesterol, drugs Metabolism of carbohydrates, protein, fats Phagocytosis (Kupffer cells, macrophages) Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 21 Hepatic Portal System End products of digestion flow through portal vein to liver Liver processes end products of digestion, discharging blood through hepatic veins and into IVC Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 22 Biliary Tree Ducts connect liver, gallbladder, pancreas to duodenum Hepatic ducts Cystic duct Common bile duct Ampulla of Vater Sphincter of Oddi Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 23 Bile Formed from blood in the liver lobules Assists in digestion of fat Stored in gallbladder Composition Water Cholesterol Bile pigments, salts Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 24 Gallbladder Pear-shaped sac on the underside of the liver Concentrates and stores bile Attached to common bile duct by cystic duct Fat in the duodenum stimulates release of the hormone cholecystokinin (CCK) CCK causes gallbladder to contract, eject bile into common bile duct and duodenum Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 25 Path of Pancreatic Digestive Enzymes Pancreatic acinar cells Main pancreatic duct Base of common bile duct Duodenum Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 26 Clinical Conditions Gallstones Bleeding Loss of clotting factors (liver failure) Esophageal varices Ascites Paracentesis Acute pancreatitis Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 27 Lesson 23-2 Objectives Explain the physiology of digestion and absorption. Describe the effects of amylases, proteases, and lipases. Describe the role of bile in the digestion of fats. Describe five categories of nutrients. Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 28 Carbohydrates: Digestion and Absorption Polysaccharides Digested by amylases to disaccharides Disaccharides Digested by disaccharidases to monosaccharides Monosaccharides Simple sugars, end products of digestion absorbed by villi Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 29 Proteins: Digestion and Absorption Gastric HCl unravels strands of protein Proteases digest protein into amino acids, which are absorbed into villi Common proteases Pepsin, stomach Trypsin, pancreas Chymotrypsin, pancreas Enterokinase, duodenum Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 30 Fats: Digestion and Absorption Fats are insoluble in water. Emulsification Bile splits big fat globules into small ones. Bile salts make fat water-soluble. Digestion Accomplished by lipases End products : Fatty acids and glycerol, absorbed by lacteals Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 31 Digestion and Absorption: Summary Trace the flow of food from the mouth to the anus. Point out entrance of each accessory organ into the digestive tract. Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 32 Nutrition: Concepts to Know Nutrition: Study of the relationship of food to body function Five categories of nutrients Carbohydrates Proteins Lipids Vitamins Minerals Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 33 Nutrition Concepts: Carbohydrates Simple Sugars Monosaccharides Disaccharides Complex Carbohydrates Polysaccharides Consist primarily of starch and fiber Most carbohydrate consumption should be in this form. Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 34 Nutrition Concepts: Proteins Essential amino acid: Not synthesized by the body; must be consumed Nonessential amino acid: Synthesized in the body; not essential to consume Complete protein: Contains all the essential amino acids Incomplete protein: Does not contain all essential amino acids Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 35 Nutrition Concepts: Fats Saturated fatty acid: Solid at room temperature Unsaturated fatty acid: Oil; liquid at room temperature Essential fatty acid: Not synthesized by the body and must be consumed; linoleic acid is an important component of cell membranes Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 36 Nutrition Concepts: Vitamins Small organic molecules that help regulate cell metabolism Fat-soluble vitamins Vitamins A, D, E, and K Can be stored in the body Water-soluble vitamins Vitamins B and C Most are not stored by the body Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 37 Nutrition Concepts: Minerals Inorganic substances needed for normal body function Sodium, chloride Potassium Calcium, phosphorus, magnesium Iron Iodine Trace elements Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 38 Appetite Control Hypothalamus Feeding center Satiety center Theories of satiety Glucostat hypothesis Lipostat hypothesis Copyright 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved. 39