© 2010 Delmar, Cengage Learning 1 PowerPoint Presentation to Accompany

© 2010 Delmar, Cengage Learning 2 Chapter 16 Nutrition and the Digestive System

© 2010 Delmar, Cengage Learning 3 Introduction Digestion: breakdown of food into smaller, usable form –Ingestion –Peristalsis –Digestion –Absorption –Defecation

© 2010 Delmar, Cengage Learning 4 4 General Organization

© 2010 Delmar, Cengage Learning 5 General Organization (cont’d) Gastrointestinal tract –Mouth, pharynx, esophagus, stomach, small intestine, large intestine Accessory organs –Teeth, tongue, salivary glands, liver, gallbladder, pancreas

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7 Histology Tunics (from the inside out) –Mucosa: mucous membrane attached to thin layer of visceral muscle –Submucosa: loose connective tissue –Muscularis: skeletal or smooth muscle –Adventitia: serous membrane made of connective and epithelial tissue Also called visceral peritoneum

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9 The Mouth or Oral Cavity Functions –Taste –Mechanical breakdown of food –Chemical digestion of carbohydrates Amylase

© 2010 Delmar, Cengage Learning 10 The Mouth or Oral Cavity (cont’d.) Structure –Cavity lined with mucous membrane –Cavity floor formed by tongue –Cavity roof formed by hard and soft palate –Cavity sides formed by cheeks –Cavity opening guarded by lips

© 2010 Delmar, Cengage Learning 11 The Mouth or Oral Cavity (cont’d.) Functions of tongue –Food manipulation, taste, speech Structure of tongue –Skeletal muscle covered with mucous membrane –Lingual frenulum –Papillae Taste buds

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© 2010 Delmar, Cengage Learning 13 The Salivary Glands Pairs of salivary glands –Parotid, submandibular, sublingual Saliva –Is 99.5% water –Has amylase which digests carbohydrates –Is buffered by bicarbonates and phosphates –Has mucin to lubricate food –Has lysozyme to destroy bacteria

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© 2010 Delmar, Cengage Learning 15 Teeth Structure: crown, neck, root Crown covered in enamel Dentin: bonelike substance enclosing pulp cavity Cementum: covers root Periodontal ligament: anchors tooth

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© 2010 Delmar, Cengage Learning 17 The Pharynx Common passageway for food and air Divisions –Nasopharynx, oropharynx, laryngopharynx Function: begins swallowing (deglutition) –Forms food bolus –Air passageways close

© 2010 Delmar, Cengage Learning 18 The Esophagus Function –Secrete mucus –Transport food Peristalsis: smooth muscle contractions push food Lower esophageal sphincter –Controls passage of food into stomach

© 2010 Delmar, Cengage Learning 19 The Stomach Functions: chemical and mechanical breakdown of food Parts –Cardia, fundus, body, pylorus Gastric glands: secretory cells –Zymogenic, parietal, mucous

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© 2010 Delmar, Cengage Learning 21 The Pancreas Functions –Acini: digestive enzymes –Islets of Langerhans: insulin and glucagon Divisions –Head, body, tail

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© 2010 Delmar, Cengage Learning 23 Animation - The Pancreas [Insert pancreas.swf]

© 2010 Delmar, Cengage Learning 24 The Liver

© 2010 Delmar, Cengage Learning 25 Introduction Functions –Produces heparin, prothrombin, thrombin –Phagocytosis of bacteria and old blood cells –Stores excess carbohydrates, minerals, and vitamins –Converts toxins into less harmful substances –Produces bile salts

© 2010 Delmar, Cengage Learning 26 The Gallbladder Pear-shaped sac Located in depression on surface of liver Stores and concentrates bile until needed Enters duodenum through common bile duct

© 2010 Delmar, Cengage Learning 27 The Small Intestine Function: absorption of digested food Divisions –Duodenum: 10 inches –Jejunum: 8 feet –Ileum: 12 feet

© 2010 Delmar, Cengage Learning 28 The Small Intestine (cont’d.) Crypts of Lieberkuhn: secrete digestive enzymes Brunner’s glands: secrete alkaline mucus Chyme: digested contents of small intestine

© 2010 Delmar, Cengage Learning 29 The Small Intestine (cont’d.) Plicae: folds in the small intestine Villi: site of nutrient absorption –Each villus is covered by microvilli –Microvilli increase absorption area –Villus contains arteriole, venule, capillary network and lacteal

© 2010 Delmar, Cengage Learning 30 The Large Intestine Reabsorption of water Manufacture and absorption of vitamins Formation and expulsion of feces

© 2010 Delmar, Cengage Learning 31 The Large Intestine (cont’d.) Cecum: pouchlike area Colon: ascending, transverse, descending –Pouches called haustrae Rectum: terminates at the anus Anus: controlled by internal and external sphincter

© 2010 Delmar, Cengage Learning 32 The Large Intestine (cont’d.) Mechanical movements –Haustral churning –Peristalsis: 3 to 12 contractions per minute –Mass peristalsis

© 2010 Delmar, Cengage Learning 33 The Formation of the Feces Feces: semisolid mass originating from chyme –Contain water, inorganic salts, epithelial cells, Escherichia coli Rectal distention initiates defecation reflex

© 2010 Delmar, Cengage Learning 34 Animation - Digestion This animation illustrates the various actions that take place throughout the digestive system after food is consumed [Insert Digestion.swf]

© 2010 Delmar, Cengage Learning 35 Summary Described the major activities of the digestive system Discussed the major organs that are part of the digestive system Explained the functions of the liver Discussed the absorption of nutrients in the small intestine and the formation of feces in the large intestine