Digestive System Chapter 14 ACCESSORY ORGANS Mouth Teeth

Digestive System Chapter 14 ACCESSORY ORGANS: Mouth • Teeth chew food • Tongue positions and tastes food Salivary glands • Saliva moistens food • Bicarbonate maintains p. H • 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. 3 a

Motility: Segmentation Copyright © 2009 Pearson Education, Inc. Figure 14. 3 b

Salivary Glands Copyright © 2009 Pearson Education, Inc. Figure 14. 5

Swallowing Copyright © 2009 Pearson Education, Inc. Figure 14. 6 a

Swallowing Copyright © 2009 Pearson Education, Inc. Figure 14. 6 b

Structure of the Stomach Wall Copyright © 2009 Pearson Education, Inc. Figure 14. 7 a–b

Stomach Function § Specific cells secrete gastric juice § Hydrochloric acid § Produces a p. H 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. 9 a–b

The Wall of the Small Intestine Copyright © 2009 Pearson Education, Inc. Figure 14. 9 c

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.