https://www.youtube.com/watch?v=dYQrqeTxC9g Ulcerative colitis is a chronic gastrointestinal disorder that involves the rectum and the colon (large intestine). Painful and stressful, it causes inflammation and ulcers in the mucosa and sub mucosa of the large intestine. Learn more about medical advances in inflammatory bowel diseases here. In this easy to understand video by osmosis, discover more about the pathophysiology (disordered process) of ulcerative colitis through animated diagrams. The video details the different signs and symptoms of the disease, treatment options, and it tells what happens when you have flares — and what happens when you go into remission.