Gastrointestinal (GI) diseases are conditions that affect any part of the digestive system, including the esophagus, stomach, small intestine, large intestine, rectum, gallbladder, pancreas and liver. Common symptoms of GI diseases include abdominal pain, vomiting, diarrhea, constipation, heartburn, and bloating. Some of the more serious GI diseases include Crohn's disease, ulcerative colitis, celiac disease, and irritable bowel syndrome. Crohn's disease is an inflammatory bowel disease that can cause inflammation and ulcers in the digestive tract. Symptoms of Crohn's include abdominal pain, bloating, diarrhea, and weight loss. Ulcerative colitis is a chronic inflammatory bowel disease that can cause inflammation and ulcers in the large intestine. Symptoms of UC include bloody diarrhea, abdominal cramps, and weight loss. Celiac disease is an autoimmune disorder that affects the small intestine and can cause damage to the villi, which are the small finger-like projections that line the small intestine. Symptoms of celiac disease include abdominal pain or discomfort, bloating, diarrhea, and weight loss.