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Inflammatory bowel disease:- Type, Pathogenesis, Etiology:- Notes


Inflammatory bowel disease (IBD) is an idiopathic disease caused by a dysregulated immune response to host intestinal microflora. The term IBD is commonly used to two bowel disease having many similarities but the conditions usually have distinctive morphological appearance. These two conditions are ulcerative colitis and Crohn’s disease.
• Ulcerative colitis: This condition causes
long-lasting inflammation and sores
(ulcers) in the innermost lining of large intestine (colon) and rectum. Classically, ulcerative colitis begins in the rectum, and in continuity extends upwards into the sigmoid colon, descending colon, transverse colon, and sometimes may involve the entire colon. The colonic contents may rarely back flow in the terminal ileum in continuity, causing ‘back wash ileitis’ in about 10% of cases.
• Crohn’s disease: Crohn’s disease may
involve any portion of the gastrointestinal tract but affect most commonly 15-25 cm of the terminal ileum which may extend into the caecum and sometimes into the ascending colon. Both ulcerative colitis and Crohn’s disease usually involve severe diarrhoea, abdominal pain, and fatigue and weight loss.
1. Immunological factors:
The exact cause of IBD is unknown, but IBD is the result of a defective immune system. A properly functioning immune system attacks foreign organisms, such as viruses and bacteria, to protect the body. In IBD, the immune system responds incorrectly to environmental triggers, which causes inflammation of the gastrointestinal tract.
2. Genetic factors:
• There is about 3 to 20 time higher incidence of occurrence of IBD in first degree relatives. This is due to genetic defect causing diminished epithelia barrier function.
• There is approximately 50% chance of development of IBD (Crohn’s disease about 60%, ulcerative colitis about 6%) in monozygotic twins. However there is no clear link between the abnormal
genes and IBD.

INFLAMMATORY BOWEL AND LIVER DISEASES Inflammatory Bowel Disease (IBD) Introduction Causes Pathophysiology of Inflammatory Bowel Disease Sign and Symptoms Diagnosis Treatment

in hypertrophy of the muscularis mucosae, fibrosis, and stricture formation, which can lead to bowel obstruction. Abscesses are common, and fistulas often penetrate into adjoining structures, including other loops of bowel and the bladder. Fistulas may even extend to the skin of the anterior abdomen or flanks. Independently of intra-abdominal disease activity, perianal fistulas and abscesses occur in 25 to 33% of cases; these complications are frequently the most troublesome aspects of Crohn’s disease.
Non-caseating granulomas can occur in
lymph nodes, peritoneum, the liver, and all layers of the bowel wall. Although
pathognomonic (a characteristic sign or symptom of a disease that can be used to diagnosis) when present, granulomas are not detected in about half of patients with Crohn’s disease. The presence of granulomas does not seem to be related to the clinical course.
11.1.4 Sign and Symptoms
Inflammatory bowel disease symptoms
vary, depending on the severity of
inflammation and where it occurs. Symptoms may range from mild to severe.
Signs and symptoms that are common to
both Crohn’s disease and ulcerative colitis include: Diarrhoea, fever and fatigue, abdominal pain and cramping, blood in stool, reduced appetite, unintended weight loss. Other symptoms may include:
Constipation, sores or swelling in the eyes, draining of pus, mucus, or stools from, around the rectum or anus (fistula), joint pain and swelling, mouth ulcers, rectal bleeding and bloody stools, swollen gums, tender, red bumps (nodules) under the, skin which may turn into skin ulcers.