What is the difference between irritable bowel syn drome (IBS), ulcerative colitis (UC), and Crohn’s disease?

Ulcerative colitis and Crohn’s disease are the two main types of inflammatory bowel disease, caused by a malfunctioning immune system. In these diseases, the immune system misfires, causing the lining of the digestive tract to become chronically inflamed and irritated. In irritable bowel syndrome (IBS) there is no obvious inflammation within the digestive tract. The underlying cause of IBS is unknown, but symptoms may arise due to uncoordinated intestinal contractions that affect bowel movements and hypersensitive nerves in the gut.