Transcript Chapter 14
Digestive System Chapter 14 ACCESSORY ORGANS: ORGANS: Mouth • Teeth chew food • Tongue positions and tastes food Salivary glands • Saliva moistens food • Bicarbonate maintains pH • Amylase digests starch • Lysozyme inhibits bacteria Liver • Produces bile • Performs various functions associated with processing and storing nutrients Gallbladder • Stores and concentrates bile Pancreas • Secretes digestive enzymes into small intestine • Secretes bicarbonate into small intestine to neutralize stomach acid Appendix • No known digestive function Pharynx • Passageway for food and air • Participates in swallowing Esophagus • Moves food from pharynx to stomach Stomach • Stores and mixes food • Begins chemical digestion of protein by enzymes and acid • Regulates delivery to the small intestine Small intestine • Digests proteins, fats, and carbohydrates • Absorbs most of the water and nutrients • Secretes digestive hormones and enzymes Large intestine • Absorbs the last of the water and nutrients • Stores waste material Sigmoid colon • Stores feces Rectum • Passageway for feces Anus • Expels undigested material Copyright © 2009 Pearson Education, Inc. Figure 14.1 Gastrointestinal (GI) Tract Wall Vein Artery Nerve Lymph vessel Serosa • Connective tissue outer covering • Protects and anchors the digestive tract Longitudinal layer Circular layer Lumen Mucosa • Mucous membrane layer • Lines the digestive tract Copyright © 2009 Pearson Education, Inc. Muscularis • Two layers of smooth muscle • Responsible for motility of the digestive tract Submucosa • Connective tissue layer • Contains blood vessels, lymph vessels, and nerves Figure 14.2 Motility: Peristalsis Copyright © 2009 Pearson Education, Inc. Figure 14.3a Motility: Segmentation Copyright © 2009 Pearson Education, Inc. Figure 14.3b Salivary Glands Copyright © 2009 Pearson Education, Inc. Figure 14.5 Swallowing Copyright © 2009 Pearson Education, Inc. Figure 14.6a Swallowing Copyright © 2009 Pearson Education, Inc. Figure 14.6b Structure of the Stomach Wall Copyright © 2009 Pearson Education, Inc. Figure 14.7a–b Stomach Function Specific cells secrete gastric juice Hydrochloric acid Produces a pH of about 2; breaks down large bits of food Mucus Protects stomach lining from acid Pepsinogen With acid, begins protein breakdown as pepsin Copyright © 2009 Pearson Education, Inc. The Stomach Copyright © 2009 Pearson Education, Inc. Figure 14.7 Peristalsis Copyright © 2009 Pearson Education, Inc. Figure 14.8 Small Intestine Functions Digestion Neutralizes acid from stomach Adds digestive enzymes and bile Breaks proteins, carbohydrates, and lipids to absorbable materials Absorption 95% of food absorbed in small intestine Copyright © 2009 Pearson Education, Inc. Small Intestine Structure Regions Duodenum Jejunum Ileum Mucosa adaptations Villi containing blood and lacteal capillaries Copyright © 2009 Pearson Education, Inc. The Wall of the Small Intestine Copyright © 2009 Pearson Education, Inc. Figure 14.9a–b The Wall of the Small Intestine Copyright © 2009 Pearson Education, Inc. Figure 14.9c Major Digestive Enzymes Copyright © 2009 Pearson Education, Inc. Table 14.1 Accessory Organs: Aid Digestion and Absorption Liver • Produces bile (water and electrolytes, cholesterol, bile salts, lecithin, and pigments) Esophagus Stomach Common bile duct Gallbladder • Stores and concentrates bile • Delivers bile to the duodenum via the common bile duct Duodenum Copyright © 2009 Pearson Education, Inc. Pancreatic duct Pancreas • Secretes enzymes (proteases, amylase, lipase) • Produces sodium bicarbonate • Delivers these products to the duodenum via ducts Figure 14.10 Accessory Organs: Aid Digestion and Absorption Copyright © 2009 Pearson Education, Inc. Figure 14.11 Large Intestine Transverse colon Ascending colon Descending colon Small intestine Ileocecal valve Cecum Appendix Sigmoid colon Rectum Internal anal sphincter (smooth muscle) Copyright © 2009 Pearson Education, Inc. External anal sphincter (skeletal muscle) Anus Anal canal Figure 14.12 Absorption of Proteins and Carbohydrates Copyright © 2009 Pearson Education, Inc. Figure 14.13 Endocrine and Nervous Systems Regulation of Digestion Regulation dependent on volume and content of food Nervous system Stretch receptors in stomach Hormones Gastrin Secretin Cholecystokinin (CCK) Copyright © 2009 Pearson Education, Inc. Absorption of Fats Copyright © 2009 Pearson Education, Inc. Figure 14.14 Nutrients: Utilized or Stored Until Needed Copyright © 2009 Pearson Education, Inc. Figure 14.15 Food Guide Pyramid Copyright © 2009 Pearson Education, Inc. Figure 14.16 Disorders of the Digestive System Disorders of the GI tract Lactose intolerance Diverticulosis Colon polyps Disorders of accessory organs Hepatitis Gallstones Copyright © 2009 Pearson Education, Inc. Disorders of the Digestive System Malnutrition Obesity Eating disorders Anorexia nervosa Bulimia Copyright © 2009 Pearson Education, Inc.