GI Linton Ch38 PP1

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GI Linton Ch38 PP1

  1. 1. CHAPTER 38 DIGESTIVE TRACT DISORDERS Linton p. 730
  2. 2. Anatomy and Physiology of the Digestive Tract Handout Linton Study Guide p. 350
  3. 3. <ul><li>Oral Cavity (Mouth) and Pharynx </li></ul><ul><li>Esophagus </li></ul><ul><li>Stomach </li></ul><ul><li>Small Intestine </li></ul><ul><li>Large Intestine and Anus </li></ul>Anatomy & Physiology of the Digestive Tract
  4. 4. Digestive Tract Anatomy
  5. 5. Mouth <ul><li>Start of Digestion </li></ul><ul><ul><li> How do the TEETH, TONGUE, and SALIVARY GLANDS aid in Digestion? ??? </li></ul></ul><ul><li>Mechanical and Chemical Digestion </li></ul><ul><ul><li>Saliva: Amylase starts to break down carbohydrates </li></ul></ul><ul><li>Parasympathetic response to something in mouth =increased salivation </li></ul>
  6. 6. Pharynx <ul><li>Muscular tube—passageway from mouth to esophagus </li></ul><ul><li>Medulla and pons cause muscle contractions as part of swallowing reflex </li></ul><ul><li>Uvula closes off nasopharynx  WHY? </li></ul><ul><li>Epiglottis closes opening to larynx  WHY? </li></ul>
  7. 7. Esophagus <ul><li>No Digestion </li></ul><ul><li>10 inches long—carries food from pharynx to stomach </li></ul><ul><ul><li> Does food reach the stomach if the body is upside down? ??? </li></ul></ul><ul><li>Peristalsis </li></ul>
  8. 8. Stomach <ul><li>Reservoir for food so digestion can take place gradually </li></ul><ul><li>Fundus, body, and pylorus </li></ul><ul><li>Rugae—folds in mucosa that flatten as the stomach fills to permit expansion </li></ul>
  9. 9. Stomach (cont) <ul><li>Presence of food in stomach stimulates secretion of hormone gastrin by gastric mucosa; increases secretion of gastric juice </li></ul><ul><li>Stomach—3 layers of muscle—mechanical digestion of food to thick liquid ( CHYME ) </li></ul><ul><li>Carbs most readily digested by stomach, then proteins and fats </li></ul><ul><li>Pyloric sphincter-contracts and relaxes; keeps food in the stomach until it is properly mixed </li></ul>
  10. 10. Stomach (cont) <ul><li>Gastric juice—parasympathetic response—secreted at site/smell of food </li></ul><ul><ul><li>Water, mucus </li></ul></ul><ul><ul><li>Rennin—digests milk proteins </li></ul></ul><ul><ul><li>Lipase—fats (triglycerides) </li></ul></ul><ul><ul><li>Pepsin+ hydrochloric acid (HCL)—start to digest proteins </li></ul></ul><ul><ul><li>Intrinsic factor—aids in absorption of B12 </li></ul></ul><ul><li>HCL creates pH of 1-2; kills bacteria </li></ul>
  11. 11. <ul><li>What keeps food and acid from backing up into the esophagus???? </li></ul><ul><ul><li> </li></ul></ul>
  12. 12. **Cardiac Sphincter = Lower esophageal sphincter (LES)
  13. 13. Small Intestine <ul><li>Chemical digestion and absorption of nutrients </li></ul><ul><li>20 feet long: duodenum, jejunum, and ileum </li></ul><ul><li>Duodenum—first 10 inches and contains hepatopancreatic ampulla (entrance of common bile duct and pancreatic duct) </li></ul><ul><li>Bile from liver and enzymes from pancreas function in the small intestine </li></ul>
  14. 14. Small Intestine (cont) <ul><li>Intestinal mucosa produces enzymes in response to chyme </li></ul><ul><li>These complete digestion of carbohydrates, proteins, and fats </li></ul><ul><ul><li>Linton p.732 Table 38-1 </li></ul></ul><ul><li>Muscle layers contract to propel food toward large intestine </li></ul>
  15. 15. Small Intestine (cont) <ul><li>Inner layer lined with thousands of VILLI which absorb digested food molecules into the blood </li></ul><ul><li>Each villus has a capillary network and lymph network (lacteal) </li></ul><ul><li>Water soluble nutrients absorbed into blood </li></ul><ul><li>Fat soluble vitamins, fatty acids, and glycerol absorbed into the lymph through lacteals </li></ul>
  16. 17. Large Intestine and Anus <ul><li>Ileocecal valve—junction of ileum of small intestine with cecum </li></ul><ul><li>Appendix attached to cecum </li></ul><ul><li>Ascending, Transverse, Descending, Sigmoid, Rectum </li></ul><ul><li>Anal sphincter allows storage of waste until voluntary elimination </li></ul><ul><li>No villi, No digestive enzymes </li></ul><ul><ul><li>What is the function of the colon? ??? </li></ul></ul>
  17. 18. <ul><li>NO Digestion in colon. Temporarily stores and eliminates undigestible material </li></ul><ul><li>Mucosa absorbs water, minerals, and vitamins produced by normal bacterial flora </li></ul><ul><li>Peristalsis propels feces into rectum; generates impulses to spinal cord (reflex; can exercise voluntary control) </li></ul><ul><li>External anal sphincter is skeletal muscle </li></ul>Large Intestine (cont)
  18. 20. Colon
  19. 21. Questions: <ul><li> What region is used by both the digestive and respiratory system? </li></ul><ul><li> Where are the first digestive juices? </li></ul><ul><li> Does the appendix have a function? </li></ul>
  20. 22. <ul><li>Tooth Enamel More Brittle, Worn Down </li></ul><ul><li>Tongue Atrophy, Receding Gums </li></ul><ul><li>Taste Sensation Lost </li></ul><ul><li>Saliva Production Decreased 33% </li></ul><ul><li>↑ rate of periodontal disease & oral cancer </li></ul><ul><li>Esophagus Motility Less, Emptying Slower </li></ul><ul><li>Weaker Gag Reflex </li></ul>
  21. 23. <ul><li>GI secretions reduced </li></ul><ul><li>Decreased Motility of Stomach </li></ul><ul><li>Decreased Gastric HCL Production </li></ul><ul><li>Fat Absorption Slower </li></ul><ul><li>Atrophy of Large/Small Intestine </li></ul><ul><li>Decreased Mucous Secretions </li></ul><ul><li>Decreased Elasticity of Rectal Wall </li></ul>
  22. 24. <ul><li>↑ Indigestion as LES loses tone </li></ul><ul><li>↑ Chance peptic ulcer </li></ul><ul><li>Colon diverticula may form </li></ul><ul><li>Constipation, hemorrhoids </li></ul><ul><li>Weakness of Intestinal Wall </li></ul><ul><li>Faulty Absorption of Vitamins B 1 and B 12 , and D, Calcium, Iron, and zinc </li></ul>
  23. 25. <ul><li>↑ risk colon cancer </li></ul><ul><li>Liver usually continues to function well, unless damaged by pathogens, i.e. hepatitis, toxins, alcohol </li></ul><ul><li>↑ tendency to form gallstones </li></ul><ul><li>Pancreas – usually continues to function well – acute pancreatitis of unknown cause somewhat more common in elderly </li></ul>

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