The Digestive System Part 2

1. The Digestive System Part 2

2. Bowel Infections

3. Bowel Infections • Clostridium difficile:An opportunistic infection associated with broad-spectrum antibiotic use (a suprainfection). • E. coli O157:H7:A strain of E. coli that produces a toxin that can make some humans very sick. This strain of E. coli is carried by cattle and is transmitted to humans through fecal contamination.

4. E. coli O157:H7

5. E. coli O157:H7 • Not everyone infected with E. coli O157:H7 gets diarrhea or any other symptoms. • Ex. people who work around cattle their entire lives may be immune to the strain • Some people get very sick or even die. • Some may develop hemolytic-uremic syndrome. • Some may develop thrombotic thrombocytopenic purpura (TTP).

6. Bowel Infections Appendicitis

7. Bowel Infections Appendicitis • Appendicitis is a localized infection of the appendix, which is a blind outpouching from the cecum.

8. AppendicitisSigns and Symptoms

9. AppendicitisSigns and Symptoms • Manifests as ill-defined pain starting in the area of the umbilicus and later progressing to the lower right quadrant. • Fever is an undependable sign. • A feeling of abdominal fullness and wanting to defecate is common. • The bowel is shut down because of inflammation. • Bowel sounds will be absent and the patient may think he/she is constipated. • Vomiting or loss of appetite is common. • If the appendix ruptures, pain may abate to return later with signs of an acute abdomen.

10. Diverticulitis

11. Diverticulitis • Diverticuli are outpouchings that have developed throughout the intestine, although they are most common in the large bowel. • Most adults have them to some degree, some more than others • They can get infected and rupture, similar to the appendix. • Signs and symptoms are similar to appendicitis except they may not necessarily be on the right lower quadrant

12. Duodenal Diverticuli

13. Duodenal Diverticuli

14. Irritable Bowel SyndromeDiagram

15. An 80-year-old man with a history of irritable bowel syndrome presented with a 5-day history of abdominal pain in the left lower quadrant, without aggravating or relieving factors Fisher R and Doma S. N Engl J Med 2009;361:286

16. Stages of Diverticulitis

17. Stages of Diverticulitis • Antibiotics are prescribed to treat the infection. • Abscesses may be drained percutaneously. • In about 10% of cases, surgery is necessary to remove a section of the colon or even to remove the entire colon (total colectomy) Jacobs D. N Engl J Med 2007;357:2057-2066

18. Colorectal CancerPolyps

19. Colorectal CancerPolyps • Third cause of death from cancer for both men and women • Most colorectal cancer starts out as a benign polyp which progresses to carcinoma in situ and finally to invasive cancer. • Not all polyps progress to cancer. • Most polyps bleed sporadically. • Bleeding can be detected by the fecal occult blood test (FOBT).

20. Colorectal CancerTreatment

21. Colorectal CancerTreatment • We can prevent the development of most colorectal cancer by removing all polyps. • Do not know which, if any, will become cancer but just to be safe all of them should be removed • Polyps, and therefore colorectal cancer, develop in the lumen of the colon. In order to become metastatic, the cancer has to invade the smooth muscle of the intestine and gain access to blood vessels and/or the peritoneal cavity. • If the cancer has not invaded very far, the prognosis is very good. • If it has metastasized, colorectal cancer always metastasizes to the liver and sometimes elsewhere.

22. ColonoscopyDiagram

23. A 56-year-old man underwent a colonoscopy after a positive fecal occult-blood test 23 Fu K and Sano Y. N Engl J Med 2006;355:1912

24. The GallbladderDiagram

25. The Gallbladder Diagram Porth, 2007, Essential of Pathophysiology, 2nd ed., Lippincott, p. 632

26. Components of Bile

27. Components of Bile • Bile salts are detergents which emulsify fat for digestion. • Bile pigments are mainly conjugated bilirubin. • Cholesterol.

28. Function of the Gallbladder

29. Function of the Gallbladder • The gallbladder also concentrates the bile by removing water • If it removes too much water, it can precipitate the bile (which is usually made of cholesterol) • Many people have gallstones and do not even know it • The problems come when the gallstones leave the gallbladder and get stuck somewhere

30. Causes of Gallstones

31. Causes of Gallstones Guyton & Hall, Textbook of Medical Physiology, 9th ed., Saunders, 1996, p.830.

32. GallstonesDiagram

33. Yekeler & Akyol, NEJM 351:2318, 2004

34. 34 Porth, 2007, Essential of Pathophysiology, 2nd ed., Lippincott, p. 653

35. Treatment of Gallstones

36. Treatment of Gallstones • Since it is felt that new stones will probably re-form if we just remove the stones, the gall bladder is usually removed. • When the gall bladder is no longer present, the bile will not be as concentrated and precipitation of the components probably will not occur. • Gall bladder surgery is typically done endoscopically through the abdominal wall. • In patients who are not candidates for surgery, stones can be fragmented with lithotripsy. If they are in the duct, they can be crushed endoscopically from the stomach.There are drugs that dissolve gallstones, but they are not used very much.

37. The LiverDiagram

38. The Liver Diagram Porth, 2007, Essential of Pathophysiology, 2nd ed., Lippincott, p. 633

39. Functions of the Liver

40. Functions of the Liver • Carbohydrate metabolism • B. Lipid metabolism. • C. Protein and energy metabolism. • Enzymes important in energy metabolism: ALT, AST, GGT • - Used as tests for liver necrosis • 2. Synthesis of plasma proteins: albumin, coagulation factors, etc.

41. Blood Flow of the Liver

42. Blood Flow of the Liver • Hepatic artery: 350 ml/min • Portal vein: 1100 ml/min • Total blood flow: 1450 ml/min, 29% of resting cardiac output. • The liver is drained by the hepatic vein, which enters the inferior vena cava.

43. Detoxification

44. Detoxification • The liver binds polar molecules to drugs and other molecules. This is called conjugation. Conjugating drugs and other molecules makes them easier to excrete, either by the kidney or in the bile. • Bilirubin is detoxified by conjugation (addition) of a glucuronic acid molecule.

45. Bilirubin Formation, Circulation, and EliminationDiagram

46. The process of bilirubin formation, circulation and elimination • Urobilinogen is responsible for the brown color of the stool Porth, 2007, Essential of Pathophysiology, 2nd ed., Lippincott, p. 636

47. Excretion by the Liver

48. Excretion by the Liver • Bile is the vehicle for excretion • What is excreted? • 1. Some drugs—most are conjugated before excretion • 2. Bilirubin • 3. Cholesterol

49. Hepatitis

50. Hepatitis • Means “inflammation of the liver.” Stating hepatitis does not indicate what the cause is, just that there is inflammation. There are several different etiologies: • Toxic Hepatitis is caused by drugs/chemicals like halothane or isoniazid. • Bacterial hepatitis is caused by such organisms as TB, Staph, or Pseudomonas • Parasitic hepatitis is caused by a variety of parasites • Viral hepatitis is caused by such viruses as Epstein Barr, and Hepatitis A, B, or C • - This is usually what theperson means