1. THE DIGESTIVE SYSTEM CHAPTER 25 http://www.youtube.com/w atch?v=9FEACJ-cXsY

2. System Overview Digestive Organs Alimentary Canal – mouth, esophagus, stomach, small intestine, large intestine, rectum http://www.youtube.com/watch? v=9FEACJ-cXsY

3. Accessory Organs – salivary glands, teeth, pancreas, liver, gall bladder

4. Digestive Processes Ingestion – taking in food Propulsion – moving food along Deglutition – breaking food into smaller pieces

5. Peristalsis – involuntary smooth muscle wavelike contractions Mechanical digestion – stomach churning Mastication - chewing

6. Chemical digestion – begins in the mouth and continues through small intestine carbohydrates into simple sugars proteins into amino acids lipids into fatty acids and glycerol

7. Absorption – through lining of small intestine Defecation – eliminating undigestible solid material

8. Anatomy Peritoneum visceral peritoneum – membrane that covers outside of organs parietal peritoneum – membrane that lines abdominopelvic cavity; forms ligaments to suspend organs.

9. Abdominal Serous Membranes

10. falciform ligament – binds liver lesser omentum – binds stomach

11. greater omentum – binds small and some of large intestine Mesocolon – binds large intestine

12. Mesentery - suspends small intestine peritoneal cavity– abdominal cavity

13. Histology 4 basic layers mucosa – innermost layer, lines lumen; secretes enzymes and hormones Submucosa – contains nerve endings, blood vessels, lymphatic vessels (lacteals); absorption

14. muscularis – smooth muscle layer; motility serosa – outermost layer; secretes serous fluid to lubricate

17. Alimentary Canal (GI Tract) Anatomy Mouth – contains teeth, tongue and salivary glands. Mechanical digestion; chemical digestion of starches begins here

18. Stomach – Chyme – consistency of toothpaste goblet cells – secrete mucus (protection) parietal cells – secretes HCl and intrinsic factor (absorbs vitamin B12)

19. chief cells – secrete pepsinogen which is activated by HCl when stomach pH rises (from ingestion of proteins)

20. G cells – secrete gastrin Rugae – folds in stomach lining Modifications – 3 muscle layers

21. Digestion – mechanical; chemical digestion of proteins begins here Absorption – water and alcohol

22. Pathology – ulcers (bacterial in origin), cancer, hiatal hernia, gastro- esophageal reflux disease

23. Small intestine – Regions: duodenum, jejunum, ileum Enzymes: peptidases (proteins) dextrinases (sugars)

24. Modifications Villi – increases surface area microvilli – secretes enzymes plicae circularis – keeps food “rotating”

25. Absorption: sugars and amino acids; fats absorbed through “lacteals”

26. Colon (with appendix)– E. coli colonies here help manufacture vitamin K Propulsion Absorption of water Pathology: diarrhea, constipation, colon cancer, diverticulitis Progression from polyp to cancer

27. Liver & Gall Bladder Responsible for producing bile, process nutrients, store glycogen, store fat soluble vitamins, detoxification.

28. Kupffer cells- phagocytic cells Hepatocytes- liver cells

29. Bile – made in liver, stored in gall bladder; emulsifies fats

30. Pathology – gall stones, cirrhosis, hepatitis, liver cancer

31. Pancreas Proteases – proteins lipases – fats amylases - starches nucleases – nucleic acids Insulin (hormone)– sugar metabolism Pathology – diabetes mellitis, pancreatitis

32. Hormonal Control Gastrin – secretion stimulated by proteins and caffeine; stimulates secretion of HCl; feedback mechanism Enterogastrone – secreted by duodenum in response to high fat content of diet; slows stomach activity

33. Secretin – produced by duodenum in response to fatty and acidic chyme stimulates pancreas to secrete bicarbonate ions and increase bile output CCK – produced by duodenum in response to fatty chyme; stimulates pancreas to secrete digestive enzymes

34. General Pathology dysentery food poisoning periodontal disease mumps hepatomas enteritis colitis ileitis Crohn’s Disease Periodontal disease mumps hepatoma

35. Any Questions?