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Chapter 14 Gastrointestinal Tract

Chapter 14 Gastrointestinal Tract. Review of Structure and Function. Structures include o ropharynx , alimentary tract, and the pancreaticobiliary tract Esophagus A tube that carries food from the pharynx to the stomach

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Chapter 14 Gastrointestinal Tract

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  1. Chapter 14 Gastrointestinal Tract

  2. Review of Structure and Function • Structures include oropharynx, alimentary tract, and the pancreaticobiliary tract • Esophagus • A tube that carries food from the pharynx to the stomach • The pylorus is a sphincter that controls the rate of emptying of the stomach into the small intestine

  3. Review of Structure and Function • Small intestine has three portions: duodenum, jejunum, and ileum • Primary function is absorption of nutrients • Large intestine has several portions: cecum, ascending, transverse, and descending colon, sigmoid colon, and rectum • Stores waste and allows for water absorption

  4. Review of Structure and Function • Mucosal layer • Submucosa • Provides structural support for the mucosa • Muscularispropria • Deep muscle layer that contracts rhythmically to move material through the alimentary tract

  5. Review of Structure and Function • Serosa • A smooth membrane on the outer surface of the alimentary tract—keeps bowel loops from tangling

  6. Review of Structure and Function • Digestion begins in the mouth with enzymes from salivary glands • In the stomach, more enzymes and now hydrochloric acid are added to facilitate digestion • The duodenum adds the most digestive enzymes, and the final stage of digestion occurs on the surface of the small intestinal epithelial cells

  7. Most Frequent and Serious Problems • Constipation • Infrequent or difficult fecal evacuation • Diarrhea • Abnormally frequent and liquid stools • These are both considered symptoms, and the underlying cause should be identified

  8. Most Frequent and Serious Problems • Irritable Bowel Syndrome • Most common disorder in the US, it has no known cause and only treatable with dietary changes • Viral enteritis “Stomach flu” • Nausea, vomiting, and diarrhea • Usually self-limited

  9. Most Frequent and Serious Problems • Diverticulosis • Occasionally causes symptoms, more common in older patients • Gastroesophageal Reflux Disease (GERD) • Occurs when acidic gastric contents rise up the esophagus from the stomach causing a burning sensation (heartburn)

  10. Most Frequent and Serious Problems • Helicobacter pylori • Causes gastritis and ulcers • Hemorrhoids • Polyps

  11. Symptoms, Signs, and Tests • Gastric analysis • Used to measure the amount of acid in the stomach • Barium enema • Barium highlights any filling defects within the rectum and colon

  12. Symptoms, Signs, and Tests • CT colonoscopy • “Virtual endoscopy” • Endoscopy • Sigmoidoscopy

  13. Symptoms, Signs, and Tests • Colonoscopy • Video capture endoscopy • Patient swallows a small camera that takes pictures and then transmits them as it travels through the digestive system

  14. Specific Diseases • Meckel’sdiverticulum • An out-pouching of the ileum • Usually unnoticed, but rarely can cause an acute abdomen

  15. Specific Diseases • Esophageal atresia • The esophagus ends in a blind pouch • Often associated with a connection between the trachea and esophagus (T-E fistula)

  16. Specific Diseases • Congenital diaphragmatic hernia • The diaphragm does not form properly, allowing abdominal organs to migrate into the thorax • Congenital pyloric stenosis • Narrowing of the outlet of the stomach, thus restricting food from moving to the small intestine

  17. Specific Diseases • Hirschsprung Disease • A lack of ganglion cells in the rectum prevent adequate fecal evacuation, leading to megacolon • Hiatal hernia • Part of the stomach slides up through the diaphragm

  18. Specific Diseases • Barrett’s esophagus • An alteration in the mucosa caused by persistent, severe reflux • Considered a pre-malignant condition

  19. Specific Diseases • Peptic Ulcer • Formed when the ability of the mucosa to heal is overcome, usually associated with increased acid production • Common in the first part of the duodenum • Can cause bleeding if the ulcer erodes into a large vessel, or perforation if it erodes through the gut wall

  20. Specific Diseases • Celiac disease • Patients are unable to have gluten as it triggers injury to the mucosa of the small intestine • Infectious Diarrhea

  21. Specific Diseases • Inguinal Hernia • An out-pouching of abdominal contents into the groin—more common in males • Acute Appendicitis • A portion of the proximal colon with no known function that can become acutely inflamed and cause illness

  22. Specific Diseases • Inflammatory Bowel Disease • Crohn’s disease and Ulcerative Colitis

  23. Specific Diseases • Pseudomembranous Colitis • Commonly occurs in the presence of prolonged antibiotic usage • Colonic Diverticulosis • Gastrointestinal (GI) tract cancer • ~20% of all cancers

  24. Specific Diseases • GI cancer • Stage is the most important predictor of survival • Colonic polyps can be either benign or malignant • Readily diagnosed through endoscopy

  25. Organ Failure • Failure of the absorption process can be tolerated for a number of days, though severe vomiting or diarrhea may prove fatal

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