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Digestive System

Digestive System. AKA. G-I Tract Alimentary Canal. Overview. Consists of Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus About 30’ in length Accessory Organs Teeth, tongue, gall bladder, salivary glands, liver and pancreas

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Digestive System

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  1. Digestive System

  2. AKA • G-I Tract • Alimentary Canal

  3. Overview • Consists of • Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus • About 30’ in length • Accessory Organs • Teeth, tongue, gall bladder, salivary glands, liver and pancreas • Glands secrete saliva, bile and enzymes

  4. GI System

  5. Process Includes • Ingestion • Mechanical – chewing, churning • Propulsion – swallowing and peristalsis • Chemical – breakdown via enzymes • Absorption – transport of end products into blood • Defecation – elimination as feces

  6. GI Process

  7. Peritoneum and cavity • Parietal peritoneum surrounds cavity, lines body wall • Visceral surrounds organ • Serous membrane allows organs to glide/expand • Retroperitoneal refers to organs in the dorsal region • Peritonitis = inflammation of peritoneum • Perforation = infection

  8. Peritoneum

  9. Quadrants

  10. Regions

  11. Regions

  12. Mesentery • Double layer of peritoneum, holds organs in place • Omentums - protection • Lesser = fatty skin, superficial near the stomach • Greater = deeper, made of connective tissue, significant fat • Three layers of fascia – Skin, Fascia, mesentary

  13. Messentery

  14. Messentary

  15. Omentum

  16. Greater Omentum

  17. Histology • Smooth muscle - peristalsis • Glands with ducts • Nerves, arteries and veins

  18. Histology

  19. MouthPoint of Origin • Oral cavity • Tongue • Soft and hard palate • Uvula • Oropharynx • Epiglottis • Larynx/pharynx • Esophagus

  20. Mouth Anatomy

  21. Mouth Anatomy

  22. Salivary glands • Produce saliva, a mixture of water, ions, mucous, and enzymes • Dissolve food • Wets food to help bind it to become a bolus • Neutralizes acids, helps growth of beneficial bacteria • Intrinsic –in tongue, palate, lips and cheeks • Extrinsic = outside mouth • Parotids • Submandibular • Sublingual

  23. Salivary Glands

  24. Pharynx • Oso • Laryngopharynx • Lined with epithelial cells for protection

  25. Pharynx

  26. Esophagus • Muscular tube • Propels swallowed food to stomach • Passes through diaphragm (esophageal hiatus) into abdomen • Join the stomach at cardiac orifice • Cardiac sphincter prevents reflux or regurgitation of acid

  27. Esophagus

  28. Esophagus

  29. Esophagus

  30. Stomach • Food churned into chyme; a paste • Secretes pepsin – a protein digesting enzyme and HCl • Waters, electrolytes, some drugs absorbed through stomach • Anatomy • Cardiac orifice, fundus, lesser and greater curvature, pylorus • Rugae = numerous longitudinal folds of mucosa which flatten as stomach fills, allows expand

  31. Stomach

  32. Stomach

  33. Stomach

  34. Junction

  35. Stomach

  36. Small Intestine • Longest part of alimentary canal • Most enzymes involved in small intestine come from pancreas • Three divisions – each approximately • Duodenum – 5% • Jejunum – 40% • Ileum – almost 50%

  37. Duodenum • Receives digestive enzymes from pancreas • Bile from gall bladder and liver • Almost all nutrients are absorbed in small intestine • Large surface area, great length

  38. Small Intestine

  39. Small Intestine

  40. Duodenum

  41. Gall Bladder • Cystic duct • Bile duct – empties into small cystic duct • Secrete bile for duodenum digestion • Bile – Right and Left hepatic ducts to common cystic duct to Gall bladder for storage • From GB to bile duct to duodenum

  42. Gall Bladder

  43. Pancreas • Exocrine gland – produces most enzymes for digestion in small intestine • Endocrine function = produce hormones that regulate levels of sugar in the blood • Main pancreatic duct

  44. Gall Bladder and Pancreas

  45. Pancreas

  46. Large Intestine • Most material has been digested by the time it reaches LI • 12-24 hours in large bowel • Little breakdown • Performs some absorption, especially water • Components • Ascending colon • Transverse colon • Descending colon • Sigmoid to rectum and anus

  47. Large Intestine

  48. Large Intestine

  49. Cecum and appendix • Cecum is a small sac (blind pouch) • Valve prevents a back up of fecal matter to ileum • Appendix • Lymph tissue neutralizes bacteria • Diverticulosus – a small outward herniation of colon, especially sigmoid • Diverticulitis – infection with leaks into peritoneal cavity may lead to peritonitis

  50. Anal Canal • ANS balance between defecation or not • PNS = increase movement • SNS = decrease • Voluntary control via external sphincter muscles

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