© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. NUTRITION AND DIGESTIVE SYSTEM Chapter 16

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction Digestion: breakdown of food into smaller, usable form –Ingestion –Peristalsis –Digestion –Absorption –Defecation

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. GENERAL ORGANIZATION

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. General Organization (cont’d) Gastrointestinal tract –Mouth, pharynx, esophagus, stomach, small intestine, large intestine Accessory organs –Teeth, tongue, salivary glands, liver, gallbladder, pancreas

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. General Organization (cont’d)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Histology (cont’d)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Mouth or Oral Cavity Functions –Taste –Mechanical breakdown of food –Chemical digestion of carbohydrates Amylase

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Mouth or Oral Cavity (cont’d.) Functions of tongue –Food manipulation, taste, speech Structure of tongue –Skeletal muscle covered with mucous membrane

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Mouth or Oral Cavity (cont’d.) Structure of tongue –Lingual frenulum –Papillae Taste buds

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Mouth or Oral Cavity (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Salivary Glands Pairs of salivary glands –Parotid, submandibular, sublingual

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Salivary Glands (cont’d.) 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

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Salivary Glands (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Teeth Structure: crown, neck, root Crown covered in enamel Dentin: bonelike substance enclosing pulp cavity Cementum: covers root Periodontal ligament: anchors tooth

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Teeth (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Pharynx Common passageway for food and air Divisions –Nasopharynx, oropharynx, laryngopharynx Function: begins swallowing (deglutition) –Forms food bolus –Air passageways close

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Esophagus Function –Secrete mucus –Transport food Peristalsis: smooth muscle contractions push food Lower esophageal sphincter –Controls passage of food into stomach

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Stomach Functions: chemical and mechanical breakdown of food Parts –Cardia, fundus, body, pylorus Gastric glands: secretory cells –Zymogenic, parietal, mucous

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Stomach (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Pancreas Functions –Acini: digestive enzymes –Islets of Langerhans: insulin and glucagon Divisions –Head, body, tail

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Pancreas (cont’d.)

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Animation – The Pancreas Click Here to Play Pancreas Animation

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Liver

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Gallbladder Pear-shaped sac Located in depression on surface of liver Stores and concentrates bile until needed Enters duodenum through common bile duct

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Small Intestine Function: absorption of digested food Divisions –Duodenum: 10 inches –Jejunum: 8 feet –Ileum: 12 feet

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Small Intestine (cont’d.) Crypts of Lieberkuhn: secrete digestive enzymes Brunner’s glands: secrete alkaline mucus Chyme: digested contents of small intestine

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Large Intestine Reabsorption of water Manufacture and absorption of vitamins Formation and expulsion of feces

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Large Intestine (cont’d.) Cecum: pouchlike area Colon: ascending, transverse, descending –Pouches called haustra Rectum: terminates at the anus Anus: controlled by internal and external sphincter

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Large Intestine (cont’d.) Mechanical movements –Haustral churning –Peristalsis: 3 to 12 contractions per minute –Mass peristalsis

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The Formation of the Feces Feces: semisolid mass originating from chyme –Contain water, inorganic salts, epithelial cells, Escherichia coli Rectal distention initiates defecation reflex

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Animation – Digestion This animation illustrates the various actions that take place throughout the digestive system after food is consumed Click Here to Play Digestion Animation

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Summary (cont’d.) Discussed the absorption of nutrients in the small intestine and the formation of feces in the large intestine