Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11The digestive system performs four basic digestive processes.Slide 13Additional functions of the digestive system.Slide 15Slide 16Gastrointestinal (GI) PhysiologyDr. Wilma A. HofmannAssociate Professor Department of Physiology and BiophysicsContact and Office Hours: Biomedical Research Building (BRB) [email protected]: 716-829-3290•The hour immediately following the lecture•By appointment: use e-mail; add PGY300 to subject lineHuman Physiology; 7th EditionChapter 21 (all pages)Chapter 3 (pages 72-80: Tissues of the body)Chapter 12 (pages 403-409: GI smooth muscles)Review material from Dr. Slaughter’s Neurophysiology lectures (Enteric System and Muscle Contraction)The Digestive System:1. OverviewThe Digestive System: OverviewFunction:The function of the gastrointestinal (GI) system or the digestive system is to digest food and absorb nutrients, salts, and water into the body’s internal environment, where the circular system can distribute them.Digestion is the process of breaking down food into molecular components that can be absorbed. Absorption is the movement of nutrients, salts, and water out of the GI tract into blood or lymph. Composition:The digestive system includes the gastrointestinal (GI) tract and the accessory organs and tissues (salivary glands, liver, gallbladder, and exocrine pancreas).Figure 21-1a modifiedAnusMicroorganisms: Bacteria, Fungi, Protozoa, ArchaeaGastrointestinal Physiology:A Brief History“Guardians of the Anus” perform enemas on a regular basis to “clean the body of toxins” 1500 B.C. 1276 A.D. 1700 A.D. 1822 A.D. 1950 A.D.WDR TVPope John XXI tries to cure his digestive troubles by putting his feces into a human bone and throwing it into the river 1500 B.C. 1276 A.D. 1700 A.D. 1822 A.D. 1950 A.D.WDR TVSun King Louis XIV receives over a thousand enemas(in the presence of the full court) 1500 B.C. 1276 A.D. 1700 A.D. 1822 A.D. 1950 A.D.WDR TV1500 B.C. 1276 A.D. 1700 A.D. 1822 A.D.“Experiments and observations on the gastric juice, and the physiology of digestion”(1833; William Beaumont) 1950 A.D.1500 B.C. 1276 A.D. 1700 A.D. 1822 A.D.Discovery of intestinal microorganisms:Initially believed to be a sign of diseases -> enemas have yet another revival 1950 A.D.Escherichia coliOver 350 Million Cases of Gastrointestinal Disease Cost at Least $180 Billion Dollars AnnuallyImportant Disorders of the Gastrointestinal System1. Acid Reflux2. Anal Cancer3. Anal/Rectal Diseases4. Appendicitis5. Barrett’s Exophagus6. Bile Duct Cancer7. Celiac Disease8. Cholecystectomy9. Cirrhosis10. Colitis11. Colon Cancer12. Colon Polyps13. Colonic Diseases14. Constipation15. Crohn’s Disease16. Cyclic Vomiting Syndrome17. Delayed Gastric Emptying18. Diarrhea19. Digestive Diseases20. Diverticulosis21. Duodenal Ulcer22. Dysentery23. Dysphagis24. Esophageal Cancer25. Fecal Incontinence26. Gall Bladder Diseases27. Gall Bladder Cancer28. Gallstones29. Gastric Cancer30. Gastroesophaegeal Reflux31. GI Bleeding32. GERD33. Heart Burn34. Helicobacter Pylori Infection 35. Hemochromatosis36. Hemorrhoids37. Hepatitis38. Hepatic Cancer39. Hernia40. Hirschsprung’s Disease41. Indigestion42. Inflamatory Bowel Disease43. Inguinal Hernia44. Intestinal Pseudo-Obstruction45. Irritable Bowel Syndrome46. Islet Cell Carcinoma47. Jaundice48. Lactose49. Liver Cancer50. Liver Diseases51. Liver Transplantation52. Menetrier’s Disease53. Pancreas Transplantation54. Pancreatic Cancer55. Pancreatic Diseases56. Peptic Ulcer57. Porphyria58. Proctitis59. Pruritus Ani60. Rectal Cancer61. Rectal Disease62. Small Intestine Cancer63. Stomach Cancer64. Stomach Disorders65. Rapid Gastric Emptying66. Stomach Ulcer67. Swallowing Disorders68. Ulcerative Colitis69. Ulcers70. Virial Hepatitis71. Whipple’s Disease72. Wilson’s DiseaseThe digestive system performs four basic digestive processes.1. Motility•The movement of food through the digestive tract -> includes various muscle types (i.e. skeletal muscle, smooth muscle) -> includes various types of movement (voluntary, involuntary)2.Secretion•Release of substances that lubricate food, aid in digestion of foods, and regulate other digestive processes (i.e. mucus, water, ions, enzymes, hormones)3.Digestion•Breakdown of foods into smaller units that can be absorbed4.Absorption•Transfer of digested end product from GI lumen to blood or lymph across layer of epithelial cellsExcretionImmune FunctionFigure 21-1aG.I. Processes are controlled by:HormonesNeurotransmittersMovement of material from cells into lumen or ECFExocrine, endocrine, and paracrine:ions, water,enzymes and hormonesChemical and mechanical breakdownof food into absorbableunitsMovement of material from GI lumen to ECF:organics, ions, and waterMixing and movementof material through GI tract by smooth muscle-> transport of chyme**chyme: a soupy substance produced by digestion Figure 21-2The four basic digestive processesAdditional functions of the digestive system.Excretion•Elimination of indigestible material and microorganismsFigure 21-1aImmune Function- GI tract is the largest immune organ of the bodyCDC estimate (2011) about foodborne diseases caused by foodborne bacteria, viruses, microbes ("pathogens") :-1 in 6 Americans gets sick each year -128,000 are hospitalized each year - 3,000 die each year Most common foodborne illnesses caused by:Norovirus, Salmonella, Clostridium perfringens, Campylobacter. •Physical barrier (GI tract wall; mucus)•Chemical barrier (strong stomach acid and other digestive substances)•Extensive gut-associated lymphoid tissue (GALT): protective responses: diarrhea, vomitingFigure 21-1aAdditional functions of the digestive systemThe Digestive System: Lectures OverviewAnatomy of the Digestive SystemBasic Processes of the Digestive System•Motility•Secretion•Regulation of GI Function•Digestion•AbsorptionThe Three Phases of Digestion•The Cephalic Phase•The Gastric Phase•The Intestinal