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Lecture Topic: “GI Disorders” Describe the mechanical and chemical basis of motility, absorption, and digestion in the GI tract. Describe the physiological mechanisms involved in anorexia, nausea, and vomiting. List the causes of esophagitis. Relate the causes of hiatal hernia to measures used in treatment of the condition. Describe the predisposing factors in development of peptic ulcers. Compare the pharmacologic actions of antacids, histamine-receptor antagonists, and mucosal protective agents as they relate to the treatment of peptic ulcer. 236 GI disorders 02/27/01 1 Objectives (cont.) Compare the characteristics of Crohn’s disease and ulcerative colitis. Describe the causes and manifestations of peritonitis and bowel obstructions. List the risk factors for colorectal cancer and screening methods as suggested by the American Cancer Society. Describe the various causes of diarrhea. Describe the pharmacologic action of opiates, anticholinergics, and fiber in the treatment of diarrhea. Describe the pharmacological action of stool softeners, saline and stimulant cathartics, and bulk-forming laxatives in the treatment of constipation. 236 GI disorders 02/27/01 2 Terms Digestion Absorption Peristalsis Peritoneum Mesentery Peritonitis Ascites Vagus nerve Mechanoreceptors Chemoreceptors Aspiration pneumonia 236 GI disorders 02/27/01 Gastrin Chyme Cholecystokinin Dumping syndrome Chief cells Parietal cells Intrinsic factor Goblet cells Lactase deficiency Fat-soluble vitamins Steatorrhea Anorexia 3 Terms Appendicitis Paralytic ileus Hematemesis Melena Occult blood Dysphagia Esophagitis Hiatal hernia Gastritis Peptic ulcer Gastroscopy 236 GI disorders 02/27/01 Phenothiazines Compazine Thorazine Antacids Histamine antagonists (H2 blockers) Inflammatory bowel disease Crohn’s Ulcerative colitis Toxic megacolon 4 Manifestations of GI Disorders Anorexia, Nausea, & Vomiting Protective function by removing noxious agent Contributes to nutritional, fluid, & electrolyte abnormalities Anorexia = loss of appetite Hypothalamus Smell Drugs 236 GI disorders & disease 02/27/01 5 Manifestations (cont.) Nausea = unpleasant subjective sensation Stimulated by distention, food, or drugs Accompanied by pallor, sweating, & tachycardia (vasoconstriction) Vomiting = forceful expulsion of contents of stomach Vomiting Center - coordination of act in medulla; direct stimulation by hypoxia, inflammation, & distention CTZ - stimulated by drugs & toxins; bradycardia, BP, dizziness Phenothiazines - decreased stimulation of CTZ 236 GI disorders 02/27/01 6 Manifestations - GI Bleeding Melena - blood in stool Hematemesis - blood in vomitus; bright red or “coffee-grounds” Occult blood - “hidden blood”, elevation of BUN 236 GI disorders 02/27/01 7 GI Tract - Structure & Function A hollow tube / Outside of Body!!! Digestion - breakdown of foodstuffs Absorption - passage of nutrients into bloodstream Main organs Esophagus, stomach, & intestine Accessory organs Teeth/tongue, salivary glands, liver, pancreas, & gallbladder 236 GI disorders 02/27/01 8 Digestion & Absorption Function GI tract - largest endocrine organ in body; hormones influence motility & secretion of electrolytes & enzymes ANS control of propulsion (peristalsis) Parasympathetic (Vagus) - speeds up Sympathetic - slows down Muscle control through “sphinctors” 236 GI disorders 02/27/01 9 Digestion and Absorption Saliva & Stomach - begin breakdown of starches & lipid-soluble foodstuffs Lysozymes & HCL - antibacterial action Small intestine - Villi provide LARGE absorptive surface area CHO - disaccharides converted to monosaccharides by brush border enzymes Fat - broken down by lipases & bile; fat-soluble vits (A, D, E, K); steatorrhea = fatty stools Protein - broken down by pancreatic enzymes 236 GI disorders 02/27/01 10 GI Motility Swallowing Coordinated by medulla & pons Esophagus - opening of LES -- vagal control (e.g. acetylcholine increases constriction) CANNOT SWALLOW AND BREATHE AT SAME TIME Dysphagia = difficulty swallowing 236 GI disorders 02/27/01 11 Motility (cont.) Stomach Acts as reservoir Emptying - Hormonal (CCK) & neural mechanisms Pyloric stenosis - infants or scarring Small intestines peristalsis - synchronized contraction & relaxation as food bolus moves through; 12/min in jejunum Inflammation - increase in bowel sounds Surgery - Decrease in peristalsis 236 GI disorders 02/27/01 12 GI Motility (cont.) Colon Compaction of fecal wastes Haustrations - mixing movements Mass propulsion -- defacation Gastrocolic reflex- wave of peristalsis following fasting period (usually overnight) 236 GI disorders 02/27/01 13 Disorders of Esophagus Esophagitis - inflammation of mucosa Acute causes ingestion of alkalis or acids infections such as candidiasis Scarring as possible sequelae Chronic causes - reflux or local irritants Decrease in LES pressure Acid reflux Increase in dietary fat Often result of Hiatal hernia 236 GI disorders 02/27/01 14 Hiatal Hernia Protrusion of stomach into chest cavity Etiology - muscle weakness; constipation Sliding hernia Tx: Small, frequent meals; antacids; no anticholinergics (decrease LES); avoid nicotine; metoclopramide (Reglan) Rolling hiatal hernia Strangulation is a potential problem! Complications: GERD and strictures 236 GI disorders 02/27/01 15 GERD Most common disorder of GI tract Weak or incompetent LES, meals high in fat Heartburn – often during night Other symptoms include wheezing, cough, & hoarseness Link between GERD & asthma – vagalmediated bronchospasm, laryngeal injury, microaspiration 236 GI disorders 02/27/01 16 Tx of GERD Conservative: sitting up while eating and several hours afterward; avoidance of high-fat meals, smoking, alcohol, chocolate, caffeine; bending for long periods of time; sleeping with HOB elevated, weightloss Pharmacological : antacids for mild disease; alginic acids, H2 blockers, Proton pump inhibitors for severe disease or strictures 236 GI disorders 02/27/01 17 Peptic Ulcer Ulceration of mucosa in UGI Gastric vs. duodenal Pathogenesis Agents: aspirin, alcohol, & H. pylori Destruction of mucosal barrier: Decrease in blood flow & bicarbonate (shock, smoking) Increased permeability to H+ (alcohol & aspirin) Decreased prostaglandins (aspirin) Increased sympathetic stimulation which inhibits Brunner’s glands & mucous secretion Increased HCL production (histamine and gastrin secreting tumors e.g. Zollinger-Ellison Syndrome) 236 GI disorders 02/27/01 18 Ulcers (cont.) Manifestations Gnawing, burning pain Pain on empty stomach Pain relieved by food or antacids Complications Hemorrhage Obstruction Perforation Diagnosis H & P, UGI, Endoscopy 236 GI disorders 02/27/01 19 Ulcers - Drug Management Antacids Give 30 mins. after meals Calcium -- constipating effect Neutralize pH Magnesium - laxative effect Aluminum - phosphate binders Alter absorption of many drugs!!! 236 GI disorders 02/27/01 20 Ulcers - Drug Management Mucosal Protective Agents Sucralfate (carafate) Polysaccharide Selectively binds to necrotic ulcer Requires acid pH for activation!! Anticholinergics Blocks vagal stimulation of gastric acid Decrease GI motility 236 GI disorders 02/27/01 21 Ulcers - Drug Management H2 receptor antagonists Blocks receptor for histamine & gastric secretion of HCL (ex. ranitidine (Zantac); Cimetidine (Tagamet); Pepcid; Axid Liver toxicities !!! Psychosis/Delirium !!! 236 GI disorders 02/27/01 22 Inflammatory Bowel Disorders Chron’s & Ulcerative Colitis Hereditary predisposition Early adulthood Remissions & exacerbations Diarrhea Weight loss Possible complications Obstruction Fistulas Toxic megacolon Cancer 236 GI disorders 02/27/01 23 Chron’s Disease Mainly affects small intestine (submucosal layer) Granulomatous lesions - “cobblestone” Bowel - “lead-pipe rigidity” Nutritional deficits Formation of fistulas & abscesses Symptoms Intermittent diarrhea; colicky pain, weight loss, F & E abnormalities; malaise; low-grade fever 236 GI disorders 02/27/01 24 Ulcerative Colitis Mainly confined to rectum & colon Spreads upward Primarily affects mucosal layer Pseudopolyps Symptoms: Up to 30-40 bloody, mucousy stools/day Fever & anorexia Abdominal cramping Weakness & fatigue 236 GI disorders 02/27/01 25 Inflammatory Bowel Disease Diagnosis & Treatment Diagnosis Sigmoidoscopy Barium enema (Chron’s) CT scan Treatment Sulfasalazine Corticosteroids Surgery -- ileostomy Hi cal, Hi prot, Hi vit diet Elemental diet 236 GI disorders 02/27/01 26 Diverticulosis Herniation of intestinal wall Risk factors: Inactivity Low-fiber diet H/O constipation Symptoms Often asymptomatic Bloating/flatulence Diarrhea/Constipation Treatment - Bulk in diet 236 GI disorders 02/27/01 27 Diverticulitis Complication of diverticulosis Inflammation & infection LLQ pain, N & V, leukocytosis Treatment: Antibiotics No SOLID food 236 GI disorders 02/27/01 28 Colorectal Cancer 2cnd most common fatal cancer!! Risk factors: Advancing age Family history Diet low in fiber, Hi in refined sugar H/O colorectal polyps Dx: Rectal exam; + occult blood; barium enema; sigmoidoscopy Tx: Surgery; pre-op radiation 236 GI disorders 02/27/01 29 Appendicitis Inflammation of appendix Causes: fecalith or twisting ?? Symptoms: Epigastric pain -- colicky--LRQ pain Abrupt onset Nausea Fever Leukocytosis Rebound tenderness Tx: Surgery 236 GI disorders 02/27/01 30 Bowel Obstruction Mechanical Post-op adhesions External hernia Intussusception Paralytic Abdominal surgery -- paralytic ileus Back injuries Pelvic fractures Inflammatory conditions 236 GI disorders 02/27/01 31 Bowel obstructions (cont.) Manifestations Distention F & E disturbances Borborygmis Visible peristalsis Vomiting (projectile) Dx: H & P; gas-filled bowel Tx: NG decompression; surgery 236 GI disorders 02/27/01 32 Peritonitis Inflammation of abdominal cavity Causes: Perforated peptic ulcer Ruptured appendix/diverticulum PID Gangrenous gallbladder Trauma 236 GI disorders 02/27/01 33 Peritonitis (cont.) Symptoms: Pain & tenderness Guarding Shallow breathing Hiccups Paralytic ileus Treatment: NG decompression; NPO; antibiotics; F & E replacement 236 GI disorders 02/27/01 34