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THE DIGESTIVE SYSTEM

THE DIGESTIVE SYSTEM. CHAPTER 25. http://www.youtube.com/watch?v=9FEACJ-cXsY. System Overview. Digestive Organs Alimentary Canal – mouth, esophagus, stomach, small intestine, large intestine, rectum. http://www.youtube.com/watch?v=9FEACJ-cXsY.

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THE DIGESTIVE SYSTEM

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  1. THE DIGESTIVE SYSTEM CHAPTER 25 http://www.youtube.com/watch?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

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

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

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

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

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

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

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

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

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

  24. 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

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

  26. Kupffer cells- phagocytic cells • Hepatocytes- liver cells

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

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

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

  30. 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

  31. 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

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

  33. Any Questions?

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