Pathophysiology of Digestive Function PDF Summer 2024

Prepared By Prof. Zeinab Al-Wahsh HU Pathophysiology of #7 Digestive Function Summer 2024 Copyright © 2017, Elsevier Inc. All rights reserved.  Clinical Manifestations of Gastrointestinal Dysfunction  Anorexia A lack of a d...

Prepared By Prof. Zeinab Al-Wahsh HU Pathophysiology of #7 Digestive Function Summer 2024 Copyright © 2017, Elsevier Inc. All rights reserved.  Clinical Manifestations of Gastrointestinal Dysfunction  Anorexia A lack of a desire to eat despite physiologic stimuli that would normally produce hunger  Vomiting The forceful emptying of the stomach and intestinal contents through the mouth Several types of stimuli initiate the vomiting reflex The common symptoms of vomiting are hypersalivation and tachycardia 2  Clinical Manifestations of Gastrointestinal Dysfunction (Cont.)  Vomiting is stimulated by: excitation of the chemoreceptor trigger zone (CTZ) by certain drugs or chemicals in the circulation ; direct excitation of the medullary emetic center by severe pain; distention or irritation of the GI tract and increased intracranial pressure 3  Clinical Manifestations of Gastrointestinal Dysfunction (Cont.)  Projectile vomiting Spontaneous vomiting that does not follow nausea or retching Projectile vomiting is caused by direct stimulation of the vomiting canter by direct neurological lesions involving the brain stem  Nausea A subjective experience that is associated with a number of conditions  Retching Nonproductive vomiting 4  Clinical Manifestations of Gastrointestinal Dysfunction (Cont.)  Constipation Defined as infrequent or difficult defecation Primary condition Normal transit (functional) Slow transit Pelvic floor or outlet dysfunction 5  Clinical Manifestations of Gastrointestinal Dysfunction (Cont.)  Constipation (Cont.) Secondary condition Caused by many different factors such as diet, medications, various disorders, aging Manifestations Straining with defecation Hard stools Sensation of incomplete emptying Manual maneuvers to facilitate stool evacuation Fewer than three bowel movements per week Manage underlying disease Copyright © 2017, Elsevier Inc. All rights reserved. 6  Clinical Manifestations of Gastrointestinal Dysfunction (Cont.)  Diarrhea Presence of loose, watery stools Acute or persistent Large-volume diarrhea Caused by excessive amounts of water or secretions or both in the intestines Small-volume diarrhea Volume of feces is not increased, usually results from excessive intestinal motility 7  Clinical Manifestations of Gastrointestinal Dysfunction (Cont.)  Diarrhea (Cont.) Major mechanisms of diarrhea Osmotic diarrhea Secretory diarrhea Motility diarrhea Systemic effects Dehydration Electrolyte imbalance Weight loss Associated with malabsorption syndromes Treated with fluid restoration, antimotility or water-absorbent medications, treatment of causal factors 8  Clinical Manifestations of Gastrointestinal Dysfunction (Cont.)  Abdominal pain Mechanical, inflammatory, or ischemic Usually associated with tissue injury and inflammation 9  Clinical Manifestations of Gastrointestinal Dysfunction (Cont.)  Gastrointestinal bleeding Upper gastrointestinal bleeding Esophagus, stomach, or duodenum Lower gastrointestinal bleeding Jejunum, ileum, colon, or rectum inflammatory bowel disease Occult bleeding Physiologic response depends on rate and amount of blood loss 10  Disorders of Motility  Dysphagia Difficulty swallowing Mechanical obstructions Functional disorders 11  Disorders of Motility  Dysphagia Manifestations Stabbing pain at the level of obstruction Discomfort after swallowing Regurgitation of undigested food Unpleasant taste sensation Vomiting Aspiration Weight loss Symptoms managed by eating small meals slowly, taking fluid with meals, and sleeping with the head elevated to prevent regurgitation and aspiration 12  Disorders of Motility (Cont.)  Gastroesophageal reflux disease (GERD) Reflux of acid and pepsin from the stomach to the esophagus that causes esophagitis Resting tone of the LES tends to be lower than normal Conditions that increase abdominal pressure or delay gastric emptying can contribute to the development of reflux esophagitis 13  Disorders of Motility (Cont.)  Gastroesophageal reflux disease (GERD) (Cont.) Manifestations Heartburn Acid regurgitation Dysphagia Chronic cough Asthma attacks Laryngitis Upper abdominal pain within 1 hour of eating Proton pump inhibitors are the agents of choice for controlling symptoms and healing esophagitis 14  Disorders of Motility (Cont.)  Hiatal hernia Diaphragmatic hernia with protrusion of the upper part of the stomach through the diaphragm and into the thorax Sliding hiatal hernia Paraesophageal hiatal hernia Mixed hiatal hernia Conservative treatment 15  Hiatal Hernia Copyright © 2017, Elsevier Inc. All rights reserved. 16  Disorders of Motility (Cont.)  Gastroparesis Delayed gastric emptying in the absence of mechanical gastric outlet obstruction Associated with diabetes mellitus, surgical vagotomy, or fundoplication Symptoms include nausea, vomiting, abdominal pain, and postprandial fullness or bloating 17  Disorders of Motility (Cont.)  Pyloric obstruction The blocking or narrowing of the opening between the stomach and the duodenum Can be acquired or congenital Manifestations Epigastric pain and fullness Nausea Succussion splash Vomiting With a prolonged obstruction, malnutrition, dehydration, and extreme debilitation Usually conservative management 18  Disorders of Motility (Cont.)  Intestinal obstruction and paralytic ileus An intestinal obstruction is any condition that prevents the flow of chyme through the intestinal lumen Simple obstruction  Mechanical blockage of the lumen Functional obstruction (paralytic ileus)  Failure of intestinal motility  Often occurs after intestinal or abdominal surgery, pancreatitis, or hypokalemia 19  Disorders of Motility  Intestinal obstruction and paralytic ileus Signs of small intestinal obstruction Colicky pains Nausea and vomiting Signs of large intestine obstruction Hypogastric pain and abdominal distention 20  Gastritis  Inflammatory disorder of the gastric mucosa  Acute gastritis Caused by injury of the protective mucosal barrier  Chronic gastritis Chronic fundal gastritis (type A, immune) Chronic antral gastritis (type B, nonimmune)  Symptoms vague 21  Peptic Ulcer Disease  A break or ulceration in the protective mucosal lining of the lower esophagus, stomach, or duodenum  Acute and chronic ulcers  Superficial Erosions  Deep 22  Peptic Ulcer Disease (Cont.)  Duodenal ulcers Most common of the peptic ulcers Developmental factors: Helicobacter pylori infection Hypersecretion of stomach acid and pepsin Use of NSAIDs Characterized by intermittent pain in the epigastric area Relieved rapidly by ingestion of food or antacids Management aimed at relieving the causes and effects of hyperacidity and preventing complications 23 Duodenal Ulcer Copyright © 2017, Elsevier Inc. All rights reserved. 24  Gastric Ulcer  Gastric ulcers tend to develop in the antral region of the stomach, adjacent to the acid-secreting mucosa of the body  Pathophysiology The primary defect is an increased mucosal permeability to hydrogen ions Gastric secretion tends to be normal or less than normal  Manifestations and treatment similar to duodenal ulcers except food cause pain 25  Malabsorption Syndromes  Maldigestion Failure of the chemical processes of digestion  Malabsorption Failure of the intestinal mucosa to absorb digested nutrients  Maldigestion and malabsorption frequently occur together 26  Malabsorption Syndromes (Cont.)  Fat-soluble vitamin deficiencies: Vitamin A Night blindness Vitamin D Decreased calcium absorption Bone pain Osteoporosis Fractures Vitamin K Prolonged prothrombin time Purpura Petechiae Vitamin E Uncertain 27  Inflammatory Bowel Disease  Ulcerative colitis and Crohn disease Chronic, relapsing inflammatory bowel disorders Genetics Environmental factors Alterations of epithelial barrier functions Altered immune reactions to intestinal flora 28  Ulcerative Colitis  Chronic inflammatory disease that causes ulceration of the colonic mucosa Sigmoid colon and rectum Begins in the rectum and may extend proximally to the entire colon Intermittent periods of remission and exacerbation 29  Ulcerative Colitis (Cont.)  Symptoms: Diarrhea (10 to 20/day) Urgency Bloody stools Cramping  Treatment Mild to moderate disease is treated with 5- aminosalicyclate therapy followed by steroids immunomodulatory agents or vedolizumab are used for serious disease Surgery for severe disease 30  Crohn Disease  Idiopathic inflammatory disorder; affects any part of the digestive tract, from mouth to anus 31  Crohn Disease (Cont.)  Causes “skip lesions”  One side of the intestinal wall may be affected and not the other  Ulcerations can produce fissures that extend into the lymphatics  Symptoms similar to ulcerative colitis  Anemia may result from malabsorption of vitamin B12 and folic acid  Treatment similar to ulcerative colitis 32  Irritable Bowel Syndrome  Symptom-based disease characterized by recurrent abdominal pain with altered bowel habits  More common in females  Associated with anxiety, depression, and reduced quality of life 33  Irritable Bowel Syndrome (Cont.)  Cause unknown but mechanisms proposed hypersensitivity Abnormal intestinal permeability, motility, and secretion Postinflammatory Alteration in gut microbiota Food allergy/intolerance Psychosocial factors 34  Irritable Bowel Syndrome (Cont.)  Manifestations Lower abdominal pain or discomfort and bloating  Symptoms are usually relieved with defecation and do not interfere with sleep  No cure, and treatment is individualized 35  Appendicitis  Inflammation of the vermiform appendix  Possible causes: Obstruction, foreign bodies, infection  Gastric or periumbilical pain Rebound tenderness to RLQ  Perforation, peritonitis, and abscess formation are the most serious complications 36  Obesity  An increase in body fat mass Body mass index greater than 30  Associated with higher all-cause mortality  Generally develops when caloric intake exceeds caloric expenditure  Major risk factor for morbidity, death, and high healthcare costs 37  Liver Disorders  Portal hypertension Abnormally high blood pressure in the portal venous system caused by resistance to portal blood flow Intrahepatic Posthepatic 38  Liver Disorders (Cont.)  Portal hypertension (Cont.) Varices Lower esophagus Stomach Abdominal wall Rectum Splenomegaly Hepatopulmonary syndrome Portopulmonary syndrome Vomiting of blood from bleeding esophageal varices is the most common clinical manifestation 39  Varices Copyright © 2017, Elsevier Inc. All rights reserved. 40  Liver Disorders  Ascites Accumulation of fluid in the peritoneal cavity Most common cause is cirrhosis Development associated with Portal hypertension Decreased synthesis of albumin by the liver Splanchnic vasodilation Renal sodium and water retention 25% mortality in 1 year if associated with cirrhosis Causes abdominal distention and increased abdominal girth and weight gain Paracentesis 41  Liver Disorders  Hepatic encephalopathy A neurologic syndrome of impaired behavioral, cognitive, and motor function The condition develops rapidly during fulminant hepatitis or slowly during course of liver disease Cells in the nervous system are vulnerable to neurotoxins absorbed from the GI tract that, because of liver dysfunction, circulate to the brain impaired ammonia metabolism 42  Liver Disorders (Cont.)  Hepatic encephalopathy (Cont.) Early symptoms Subtle changes in personality, memory loss, irritability, disinhibition, lethargy, and sleep disturbances Later symptoms Confusion, disorientation to time and space, flapping tremor of the hands (asterixis), slow speech, bradykinesia, stupor, convulsions, and coma 43  Liver Disorders (Cont.)  Jaundice (icterus) Caused by hyperbilirubinemia Obstructive jaundice Extrahepatic obstruction Intrahepatic obstruction Hemolytic jaundice Prehepatic jaundice Excessive hemolysis of red blood cells Characterized by dark urine, yellow discoloration of sclera and skin, and light-colored stools 44  Cirrhosis  Irreversible inflammatory, fibrotic liver disease  Biliary channels become obstructed and cause portal hypertension  Severity and rate of progression depend on the cause  Many causes 45  Viral Hepatitis  Systemic viral disease that primarily affects the liver  5 types (A, B, C, D, and E) Can cause acute, icteric illness  Spectrum of manifestations ranges from absence of symptoms to fulminating hepatitis, with rapid onset of liver failure and coma 46  Disorders of the Gallbladder  Obstruction or inflammation (cholecystitis) is the most common cause of gallbladder problems  Cholelithiasis—gallstone formation Risks Obesity Middle age Female Oral contraceptive use Rapid weight loss Gallbladder, pancreas, or ileal disease 47  Disorders of the Gallbladder (Cont.)  Gallstones Formed from impaired metabolism of cholesterol, bilirubin, and bile acids Type depends on chemical composition Cholesterol  Formed from bile that is supersaturated with cholesterol produced by the liver Pigmented brown  Formed from calcium bilirubinate and fatty acid soaps that bind with calcium Black  Composed of calcium bilirubinate with mucin glycoproteins  Associated with chronic liver disease and hemolytic disease 48 Disorders of the Gallbladder (Cont.)  Gallstones (Cont.) Often asymptomatic or vague Epigastric and right hypochondrium pain Intolerance to fatty foods 49  Gallstones Copyright © 2017, Elsevier Inc. All rights reserved. 50  Disorders of the Gallbladder  Cholecystitis Almost always caused by a gallstone lodged in the cystic duct Pain is similar to that caused by gallstones Fever, leukocytosis, rebound tenderness, and abdominal muscle guarding are common findings 51  Disorders of the Pancreas  Pancreatitis Inflammation of the pancreas Develops because of obstruction to the outflow of pancreatic digestive enzymes caused by bile and pancreatic duct obstruction is initially triggered by backup of pancreatic enzymes 52  Cancer of the Gastrointestinal Tract  Esophagus Squamous cell carcinoma Adenocarcinoma Risk factors include chronic alcohol use combined with smoking or chewing tobacco, hot and irritant (alcohol) drinks, food containing nitrosamines, and achalasia Frequent symptoms are chest pain and dysphagia 53  Cancer of the Gastrointestinal Tract  Stomach Associated with atrophic gastritis and Helicobacter pylori Sporadic and associated with consumption of heavily salted and preserved foods, low intake of fruits and vegetables, and use of tobacco and alcohol Vague symptoms early such as loss of appetite, malaise, and indigestion Later symptoms of unexplained weight loss, upper abdominal pain, vomiting, change in bowel habits, and anemia 54  Cancer of the Gastrointestinal Tract  Colon and rectum Most are sporadic or associated with a family history of colorectal cancer Caused by multiple gene alterations and environmental interactions Familial adenomatous polyposis Hereditary nonpolyposis Colorectal polyps Neoplastic polyps Symptoms depend on the location, size, and shape of the lesion and are silent in the early stages 55  Cancer of the Accessory Organs of Digestion  Liver Usually caused by metastatic spread from a primary site elsewhere in the body Hepatocellular carcinoma Usually asymptomatic Cholangiocellular carcinoma Commonly presents insidiously as pain, loss of appetite, weight loss, and gradual onset of jaundice 56  Cancer of the Accessory Organs of Digestion (Cont.)  Gallbladder Usually caused by metastasis Chronic inflammation may trigger dysplasia and progress to metaplasia Early stages usually asymptomatic Usually caught in late stages 57  Cancer of the Accessory Organs of Digestion (Cont.)  Pancreas Ductal adenocarcinomas Pancreatic tumors from metaplastic exocrine cells in the ducts Chronic pancreatitis and inflammatory cytokines support tumor growth When symptoms occur, there usually has been a malignant transformation 58