1 / 37

Nutrition and Digestive System

Chapter 16. Nutrition and Digestive System. Introduction. Digestion: breakdown of food into smaller, usable form Ingestion Peristalsis Digestion Absorption Defecation. General Organization. General Organization (cont ’ d). Gastrointestinal tract

lherb
Download Presentation

Nutrition and Digestive System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 16 Nutrition and Digestive System

  2. Introduction • Digestion: breakdown of food into smaller, usable form • Ingestion • Peristalsis • Digestion • Absorption • Defecation

  3. General Organization

  4. General Organization (cont’d) • Gastrointestinal tract • Mouth, pharynx, esophagus, stomach, small intestine, large intestine • Accessory organs • Teeth, tongue, salivary glands, liver, gallbladder, pancreas

  5. General Organization (cont’d)

  6. 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

  7. Histology (cont’d)

  8. The Mouth or Oral Cavity • Functions • Taste • Mechanical breakdown of food • Chemical digestion of carbohydrates • Amylase

  9. 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

  10. The Mouth or Oral Cavity (cont’d.) • Functions of tongue • Food manipulation, taste, speech • Structure of tongue • Skeletal muscle covered with mucous membrane

  11. The Mouth or Oral Cavity (cont’d.) • Structure of tongue • Lingual frenulum • Papillae • Taste buds

  12. The Mouth or Oral Cavity (cont’d.)

  13. The Salivary Glands • Pairs of salivary glands • Parotid, submandibular, sublingual

  14. 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

  15. The Salivary Glands (cont’d.)

  16. Teeth • Structure: crown, neck, root • Crown covered in enamel • Dentin: bonelike substance enclosing pulp cavity • Cementum: covers root • Periodontal ligament: anchors tooth

  17. Teeth (cont’d.)

  18. The Pharynx • Common passageway for food and air • Divisions • Nasopharynx, oropharynx, laryngopharynx • Function: begins swallowing (deglutition) • Forms food bolus • Air passageways close

  19. The Esophagus • Function • Secrete mucus • Transport food • Peristalsis: smooth muscle contractions push food • Lower esophageal sphincter • Controls passage of food into stomach

  20. The Stomach • Functions: chemical and mechanical breakdown of food • Parts • Cardia, fundus, body, pylorus • Gastric glands: secretory cells • Zymogenic, parietal, mucous

  21. The Stomach (cont’d.)

  22. The Pancreas • Functions • Acini: digestive enzymes • Islets of Langerhans: insulin and glucagon • Divisions • Head, body, tail

  23. The Pancreas (cont’d.)

  24. Animation – The Pancreas Click Here to Play Pancreas Animation

  25. The Liver

  26. 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

  27. The Gallbladder • Pear-shaped sac • Located in depression on surface of liver • Stores and concentrates bile until needed • Enters duodenum through common bile duct

  28. The Small Intestine • Function: absorption of digested food • Divisions • Duodenum: 10 inches • Jejunum: 8 feet • Ileum: 12 feet

  29. The Small Intestine (cont’d.) • Crypts of Lieberkuhn: secrete digestive enzymes • Brunner’s glands: secrete alkaline mucus • Chyme: digested contents of small intestine

  30. 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

  31. The Large Intestine • Reabsorption of water • Manufacture and absorption of vitamins • Formation and expulsion of feces

  32. 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

  33. The Large Intestine (cont’d.) • Mechanical movements • Haustral churning • Peristalsis: 3 to 12 contractions per minute • Mass peristalsis

  34. The Formation of the Feces • Feces: semisolid mass originating from chyme • Contain water, inorganic salts, epithelial cells, Escherichia coli • Rectal distention initiates defecation reflex

  35. 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

  36. 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

  37. Summary (cont’d.) • Discussed the absorption of nutrients in the small intestine and the formation of feces in the large intestine

More Related