Gastrointestinal Disorders Introduction

1. Gastrointestinal DisordersIntroduction Dr. Arun R Nair Dept. of PM S.K.H.M.C

2. APPROACH TO THE PATIENT WITH GASTROINTESTINAL DISEASE Gastro Intestinal Diseases

3. FUNCTIONS OF THE GASTROINTESTINAL TRACT • The GI tract serves two main functions— • Assimilation of nutrients • Elimination of waste. • In the mouth - food is processed, mixed with salivary amylase, and delivered to the luminal GI tract. • The esophagus- propels the bolus into the stomach, and the lower esophageal sphincter prevents oral reflux of gastric contents. • The stomach furthers food preparation by triturating and mixing the bolus with pepsin and acid. Gastric motor activities exhibit regional variability: • the proximal stomach serves a storage function by relaxing to accommodate the meal; • the distal stomach exhibits phasic contractions that propel solid food residue against the pylorus, where it is repeatedly propelled proximally for further mixing before it is emptied into the duodenum; • (3) finally, the stomach secretes intrinsic factor for vitamin B12 absorption. Gastro Intestinal Diseases

4. The small intestine serves most of the nutrient absorptive function of the gut,. The villous architecture to provide maximal surface area for absorption and is endowed with specialized enzymes and transporters. Triturated food from the stomach is mixed with pancreatic juice and bile in the proximal duodenum to facilitate digestion. Pancreatic juice contains the main enzymes for carbohydrate, protein, and fat digestion as well as bicarbonate to optimize the pH for activation of these enzymes. Bile secreted by the liver and stored in the gallbladder is essential for intestinal lipid digestion. The proximal intestine is optimized for rapid absorption of nutrient breakdown products and most minerals, while the ileum is better suited for absorption of vitamin B12 and bile acids. The small intestine also aids in waste elimination. Motor function of the small intestine delivers indigestible food residue and sloughed enterocytes into the colon for further processing. The small intestine terminates in the ileocecal junction, a sphincteric structure that prevents coloileal reflux and maintains small-intestinal sterility. Gastro Intestinal Diseases

5. The colon prepares the waste material for controlled evacuation. The colonic mucosa dehydrates the stool, decreasing daily fecalvolumes from the 1000 to 1500 mL delivered from the ileum to the 100 to 200 mL expelled from the rectum. The colonic lumen possesses a dense bacterial colonization that ferments undigested carbohydrates and short-chain fatty acids. Colonic motor patterns exhibit a to and- fro character that facilitates slow fecal desiccation. The proximal colon serves to mix and absorb fluid, while the distal colon exhibits peristaltic contractions and mass actions that function to expel the stool. The colon terminates in the anus, a structure with volitional and involuntary controls to permit retention of the fecal bolus until it can be released in a socially convenient setting Gastro Intestinal Diseases

6. OVERVIEW OF GASTROINTESTINAL DISEASES • GI diseases are manifestations of alterations in nutrient assimilation or waste evacuation or in the activities supporting these main functions. • Impaired Digestion and Absorption • Altered Secretion • Altered Gut Transit • Immune Dysregulation • Impaired Gut Blood Flow • Neoplastic Degeneration • Disorders without Obvious Organic Abnormalities • Genetic Influences Gastro Intestinal Diseases

7. SYMPTOMS OF GASTROINTESTINAL DISEASE The most common GI symptoms are Abdominal Pain, Heart Burn, Nausea and Vomiting, Altered Bowel Habits, GI Bleeding, and Jaundice. Others are Dysphagia, Anorexia, Weight Loss, Fatigue, and Extra-intestinal Symptoms. Common Causes of Common GI Symptoms Diarrhea Infection Poorly absorbed sugars Inflammatory bowel disease Microscopic colitis Functional bowel disorder Celiac disease Pancreatic insufficiency Hyperthyroidism Ischemia Endocrine tumor ABDOMINAL PAIN Appendicitis Gallstone disease Pancreatitis Diverticulitis Ulcer disease Esophagitis GI obstruction Inflammatory bowel disease Functional bowel disorder Vascular disease Gynecologic causes Renal stone Nausea and Vomiting Medications GI obstruction Motor disorders Functional bowel disorder Enteric infection Pregnancy Endocrine disease Motion sickness Central nervous system disease Gastro Intestinal Diseases

8. Common Causes of Common GI Symptoms (con’t) GI Bleeding Ulcer disease Esophagitis Varices Vascular lesions Neoplasm Diverticula Hemorrhoids Fissures Inflammatory bowel disease Infectious colitis Obstructive Jaundice Bile duct stones Cholangiocarcinoma Cholangitis Sclerosing cholangitis Ampullary stenosis Ampullary carcinoma Pancreatitis Pancreatic tumor Gastro Intestinal Diseases

9. Other Symptoms Dysphagia, odynophagia, and unexplained chest pain suggest esophageal disease. A globus sensation is reported with esophagopharyngeal conditions but also occurs with functional GI disorders. Weight loss, anorexia, and fatigue are nonspecific symptoms of neoplastic, inflammatory, gut motor, pancreatic, small bowel mucosal, and psychiatric conditions. Fever is reported with inflammatory illness, but malignancies also evoke febrile responses. GI disorders also produce extraintestinal symptoms. IBDis associated with hepatobiliary dysfunction, skin and eye lesions, and arthritis. Celiac disease may present with dermatitis herpetiformis. Jaundice can produce pruritus. Systemic lupus may cause gut ischemia, presenting with pain or bleeding. Overwhelming stress or severe burns may lead to gastric ulcer formation. Gastro Intestinal Diseases