What disease affects the gastrointestinal tract?

Celiac disease, ulcerative colitis, Crohn's disease, and irritable bowel syndrome (IBS) all involve the gastrointestinal tract, but the focus here is to identify which condition specifically affects it.

Crohn's disease is a type of inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract from the mouth to the anus, but it most commonly affects the end of the small intestine and the beginning of the large intestine. This disease is characterized by inflammation that can penetrate deep into the layers of the bowel tissue, leading to a wide range of symptoms including abdominal pain, diarrhea, fatigue, and malnutrition.

Celiac disease is an autoimmune reaction to gluten that primarily affects the small intestine, leading to damage of the intestinal lining when gluten is consumed. Ulcerative colitis, also an IBD, specifically affects the colon and rectum, causing continuous inflammation and ulcers in the inner lining of the colon. IBS is a functional gastrointestinal disorder that affects how the intestines work but does not cause the inflammation or damage to the gastrointestinal tract that the former diseases do.

Therefore, among the listed conditions, Crohn's disease stands out as it is comprehensively recognized for its significant and variable effects throughout the gastrointestinal tract,