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. Mouth Point 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

51. Anal Canal

52. Defecation

53. 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

54. Liver

55. Liver

56. Liver

57. Liver