Disorders of Gastrointestinal Function PDF

Chapter 37 Disorders of Gastrointestinal Function Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Copyright © 2020 Wolters Kluwer All Rights Reserved Signs and Symptoms Common to Gastrointestinal Disorders  Anorexia  Nausea  Vomiting  Gastrointestina...

Chapter 37 Disorders of Gastrointestinal Function Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins Copyright © 2020 Wolters Kluwer All Rights Reserved Signs and Symptoms Common to Gastrointestinal Disorders  Anorexia  Nausea  Vomiting  Gastrointestinal bleeding Copyright © 2020 Wolters Kluwer All Rights Reserved Anorexia, Nausea, Retching, and Vomiting  Anorexia, nausea, and vomiting are physiologic responses that are common to many GI disorders.  Retching consists of the rhythmic spasmodic movements of the diaphragm, chest wall, and abdominal muscles.  These responses are protective to the extent that they signal the presence of disease and, in the case of vomiting, remove noxious agents from the GI tract.  They can also contribute to impaired intake or loss of fluids and nutrients. Copyright © 2020 Wolters Kluwer All Rights Reserved Vomiting and Neural Structures  Vomiting involves two functionally distinct medullary centers—the vomiting center and the chemoreceptor trigger zone.  The act of vomiting is thought to be a reflex that is integrated in the vomiting center, which is located in the dorsal portion of the reticular formation of the medulla near the sensory nuclei of the vagus.  The chemoreceptor trigger zone is located in a small area on the floor of the fourth ventricle, where it is exposed to both blood and cerebrospinal fluid. It is thought to mediate the emetic effects of blood-borne drugs and toxins. Copyright © 2020 Wolters Kluwer All Rights Reserved Swallowing  Mechanism o Depends on the coordinated action of the tongue and pharynx o These structures are innervated by cranial nerves V, IX, X, and XII.  Alterations o Dysphagia: Difficulty in swallowing o Odynophagia: Painful swallowing o Achalasia: Failure of the esophageal sphincter to relax Copyright © 2020 Wolters Kluwer All Rights Reserved Question #1  Which of the following does not involve an alteration in the esophagus or swallowing? A. Dysphagia B. Odynophagia C. Achalasia D. GERD Copyright © 2020 Wolters Kluwer All Rights Reserved Answer #1  D. GERD  Rationale: GERD refers to the backward movement of gastric contents into the esophagus or beyond, into oral cavity or lung. This condition causes heartburn or pyrosis. Dysphagia produces narrowing of the esophagus and difficulty swallowing. Odynophagia is pain on swallowing food or fluids and may be associated with disorders of the esophagus. Achalasia occurs when the lower esophageal sphincter fails to relax due to a disruption in the input from the enteric neural plexus and the vagus nerve. Copyright © 2020 Wolters Kluwer All Rights Reserved Gastroesophageal Reflux  Heartburn  Avoiding large meals o 30 to 60 minutes after  Avoiding alcohol use and meal smoking o Evening onset  Eating meals sitting up o Pain in the epigastric  Avoiding recumbent position area that radiates to several hours after a meal the throat, shoulder, or back  Avoiding bending for long periods  Sleeping with the head elevated  Losing weight if overweight Copyright © 2020 Wolters Kluwer All Rights Reserved Copyright © 2020 Wolters Kluwer All Rights Reserved Complaints Accompanying Esophageal Diverticulum  The food stops before it reaches the stomach.  Gurgling  Belching  Coughing  Foul-smelling breath Copyright © 2020 Wolters Kluwer All Rights Reserved Esophageal Cancer  Squamous cell carcinoma  Dysphagia o Alcohol and tobacco  Weight loss use  Anorexia  Adenocarcinoma  Fatigue o Barrett esophagus  Painful swallowing  Not easily caught Copyright © 2020 Wolters Kluwer All Rights Reserved Factors Contributing to the Protection of the Gastric Mucosa  Gastric Mucosal Barrier o An impermeable epithelial cell surface covering o Mechanisms for the selective transport of hydrogen and bicarbonate ions o The characteristics of gastric mucus Copyright © 2020 Wolters Kluwer All Rights Reserved Types of Mucus Protecting the Gastric Mucosa #1  Water-Insoluble Mucus o Forms a thin, stable gel that adheres to the gastric mucosal surface o Provides protection from the proteolytic (protein- digesting) actions of pepsin o Forms an unstirred layer that traps bicarbonate, forming an alkaline interface between the luminal contents of the stomach and its mucosal surface Copyright © 2020 Wolters Kluwer All Rights Reserved Types of Mucus Protecting the Gastric Mucosa #2  Water-Soluble Mucus o Washed from the mucosal surface o Mixes with the luminal contents o Its viscid nature makes it a lubricant that prevents mechanical damage to the mucosal surface. Copyright © 2020 Wolters Kluwer All Rights Reserved Major Causes of Gastric Irritation and Ulcer Formation  Aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) o Irritate the gastric mucosa and inhibit prostaglandin synthesis  Infection with H. pylori o Thrives in an acid environment of the stomach o Disrupts the mucosal barrier that protects the stomach from harmful effects of its digestive enzymes Copyright © 2020 Wolters Kluwer All Rights Reserved Types of Gastritis  Acute Gastritis o A transient inflammation of the gastric mucosa o Most commonly associated with local irritants such as bacterial endotoxins, alcohol, and aspirin  Chronic Gastritis o Characterized by the absence of grossly visible erosions and the presence of chronic inflammatory changes o Leads eventually to atrophy of the glandular epithelium of the stomach Copyright © 2020 Wolters Kluwer All Rights Reserved Major Types of Chronic Gastritis  Helicobacter pylori gastritis  Autoimmune gastritis  Multifocal atrophic gastritis  Chemical gastropathy Copyright © 2020 Wolters Kluwer All Rights Reserved Question #2  NSAIDs and aspirin contribute to the formation of gastritis by inhibiting the _____________. A. immune system B. production of acid C. synthesis of prostaglandins D. production of mucus Copyright © 2020 Wolters Kluwer All Rights Reserved Answer #2  C. synthesis of prostaglandins  Rationale: The synthesis of prostaglandins is decreased due to the anti-inflammatory action of the drugs; therefore, acid production is unregulated. Copyright © 2020 Wolters Kluwer All Rights Reserved Helicobacter pylori  Colonize the mucus-secreting epithelial cells of the stomach.  Produce enzymes and toxins that have the capacity to interfere with the local protection of the gastric mucosa against acid.  Produce intense inflammation.  Elicit an immune response. Copyright © 2020 Wolters Kluwer All Rights Reserved Methods for Establishing Presence of H. pylori Infection  C urea breath test using a radioactive carbon isotope  Stool antigen test  Endoscopic biopsy for urease testing  Blood tests to obtain serologic titers of H. pylori antibodies Copyright © 2020 Wolters Kluwer All Rights Reserved Peptic Ulcer  Ulcerative disorders that occur in areas of the upper gastrointestinal tract that are exposed to acid–pepsin secretions  Spontaneous remissions and exacerbations are common  Causes o H. pylori o Aspirin o Age o Warfarin o Smoking Copyright © 2020 Wolters Kluwer All Rights Reserved Copyright © 2020 Wolters Kluwer All Rights Reserved Complications of Peptic Ulcer #1  Hemorrhage o Caused by bleeding from granulation tissue or from erosion of an ulcer into an artery or vein  Obstruction o Caused by edema, spasm, or contraction of scar tissue and interference with the free passage of gastric contents through the pylorus or adjacent areas Copyright © 2020 Wolters Kluwer All Rights Reserved Complications of Peptic Ulcer #2  Perforation o Occurs when an ulcer erodes through all the layers of the stomach or duodenum wall Copyright © 2020 Wolters Kluwer All Rights Reserved Gastrointestinal Tract Bleeding  Hematemesis o Blood in the vomitus o May be bright red or have coffee ground appearance  Melena o Blood in the stool o Ranges in color from bright red to tarry black o May be occult (hidden) Copyright © 2020 Wolters Kluwer All Rights Reserved Treatment of Peptic Ulcer  Eradicate the cause and promote a permanent cure for the disease. o Eradicating H. pylori o Relieving ulcer symptoms o Healing the ulcer crater  Acid-neutralizing, acid-inhibiting drugs, and mucosal protective  Antacids  Proton pump inhibitors Copyright © 2020 Wolters Kluwer All Rights Reserved Risk Factors for Development of Stress Ulcers  Large surface area burns  Trauma  Sepsis  Acute respiratory distress syndrome  Severe liver failure  Major surgical procedures  Zollinger-Ellison syndrome Copyright © 2020 Wolters Kluwer All Rights Reserved Risk Factors for Development of Gastric Cancer  Genetic predisposition  Carcinogenic factors in the diet  Autoimmune gastritis  Gastric adenomas or polyps Copyright © 2020 Wolters Kluwer All Rights Reserved Conditions Causing Altered Intestinal Function  Irritable bowel disease  Inflammatory bowel disease  Diverticulitis  Appendicitis  Alterations in bowel motility  Malabsorption syndrome  Cancer of the colon and rectum Copyright © 2020 Wolters Kluwer All Rights Reserved Infections of the Intestine  Viral Infection o Rotavirus  Bacterial Infection o Clostridium difficile colitis o Escherichia coli O157:H7 Infection  Protozoal Infection o E. histolytica Copyright © 2020 Wolters Kluwer All Rights Reserved Characteristics of Irritable Bowel Disease  Persistent or recurrent symptoms of abdominal pain  Altered bowel function  Varying complaints of flatulence, bloatedness  Nausea and anorexia  Constipation or diarrhea  Anxiety or depression Copyright © 2020 Wolters Kluwer All Rights Reserved Inflammatory Bowel Disease  Crohn Disease o A recurrent, granulomatous type of inflammatory response that can affect any area of the gastrointestinal tract from the mouth to the anus  Ulcerative Colitis o A nonspecific inflammatory condition of the colon Copyright © 2020 Wolters Kluwer All Rights Reserved Copyright © 2020 Wolters Kluwer All Rights Reserved Symptoms of Diverticulitis  Pain in the lower left quadrant  Nausea and vomiting  Tenderness in the lower left quadrant  A slight fever  An elevated white blood cell count Copyright © 2020 Wolters Kluwer All Rights Reserved Appendicitis  The appendix becomes inflamed, swollen, and gangrenous, and it eventually perforates if not treated.  Appendicitis is related to intraluminal obstruction with a fecalith (i.e., hard piece of stool), gallstones, tumors, parasites, or lymphatic tissue. Copyright © 2020 Wolters Kluwer All Rights Reserved Copyright © 2020 Wolters Kluwer All Rights Reserved Types of Diarrhea  Large Volume o Osmotic o Secretory  Small Volume o Inflammatory bowel disease o Infectious disease o Irritable colon Copyright © 2020 Wolters Kluwer All Rights Reserved Manifestations of Classic Form of Celiac Disease  Presents in infancy  Manifests as o Failure to thrive o Diarrhea o Abdominal distention o Occasionally, severe malnutrition Copyright © 2020 Wolters Kluwer All Rights Reserved Common Causes of Constipation  Failure to respond to the urge to defecate  Inadequate fiber in the diet  Inadequate fluid intake  Weakness of the abdominal muscles  Inactivity and bed rest  Pregnancy  Hemorrhoids Copyright © 2020 Wolters Kluwer All Rights Reserved Fecal Impaction  Painful anorectal disease  Tumors  Neurogenic disease  Use of constipating antacids or bulk laxatives  A low-residue diet  Drug-induced colonic stasis  Prolonged bed rest and debility Copyright © 2020 Wolters Kluwer All Rights Reserved Intestinal Obstruction #1  Mechanical obstruction can result from post operative causes such as external hernia and postoperative adhesions.  Paralytic, or adynamic, obstruction results from neurogenic or muscular impairment of peristalsis. Copyright © 2020 Wolters Kluwer All Rights Reserved Intestinal Obstruction #2  Mechanical  Abdominal distention  Paralytic  Loss of fluids and electrolytes Copyright © 2020 Wolters Kluwer All Rights Reserved Copyright © 2020 Wolters Kluwer All Rights Reserved Copyright © 2020 Wolters Kluwer All Rights Reserved Peritoneal Cavity and Peritonitis  Permits rapid absorption  Perforated peptic ulcer of bacterial toxins  Ruptured appendix  Favors the dissemination  Perforated diverticulum of contaminants  Gangrenous bowel  Great inflammatory response  Pelvic inflammatory disease o Thick, fibrinous protective substance  Gangrenous gallbladder  Abdominal trauma and wounds Copyright © 2020 Wolters Kluwer All Rights Reserved Copyright © 2020 Wolters Kluwer All Rights Reserved Copyright © 2020 Wolters Kluwer All Rights Reserved Intestinal Malabsorption  Symptoms  Failure to transport dietary o Diarrhea constituents from the lumen of the intestine to o Steatorrhea the extracellular fluid o Flatulence  Causes o Bloating o Celiac disease o Abdominal pain  Inflammatory o Cramps reaction o Weakness, muscle wasting  Neoplasm o Weight loss and  Colorectal cancer abdominal distention Copyright © 2020 Wolters Kluwer All Rights Reserved Colorectal Cancers  Age  Stool occult blood tests  Family history  Digital rectal  Crohn disease examination  X-ray studies using  Ulcerative colitis barium (e.g., barium  Familial adenomatous enema) polyposis  Flexible sigmoidoscopy  Diet and colonoscopy Copyright © 2020 Wolters Kluwer All Rights Reserved