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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. Regions

  10. 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

  11. Messentery

  12. Messentary

  13. Omentum

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

  15. Histology

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

  17. Mouth Anatomy

  18. Mouth Anatomy

  19. 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

  20. Salivary Glands

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

  22. Pharynx

  23. 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

  24. Esophagus

  25. Esophagus

  26. 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

  27. Stomach

  28. Stomach

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

  30. 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

  31. Small Intestine

  32. Small Intestine

  33. 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

  34. 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

  35. Gall Bladder and Pancreas

  36. 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

  37. Large Intestine

  38. 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

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

  40. Anal Canal

  41. Defecation

  42. Liver • Largest gland in the body (1.4 kg – 3 lbs.) • Produces bile • Stored in GB • Emulsifies fats • Involved in metabolism • Diaphramatic and visceral surface • Right and left lobes • Porta hepatis = major vessels and nerves • Right and left hepatic ducts, common bile, common

  43. Liver

  44. Liver

  45. Liver

  46. Study Points • Know the components of GI Tract • Know the peritoneum • Understand smooth muscle control • Know the various ducts and how they connect to specific organs • Understand the role of the stomach v. small intestine v. large intestine

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