The digestive juices break the food down into smaller chemical pieces or nutrients. The nutrients are absorbed into the bloodstream through the small intestine and carried to all parts of the body. Nutrients are needed for the body to grow and remain healthy. The water and solid waste that remain after the nutrients are absorbed move into the large intestine. Most of the remaining water is absorbed into the bloodstream from the colon.
Ulcerative colitis causes inflammation of the lining of the large intestine.
When inflamed, the lining of the intestinal wall is red and swollen, becomes ulcerated, and bleeds. One theory is based on genetics indicating that IBD does run in families. About 15 percent to 30 percent of patients with IBD have a relative with the disease. There is research going on to find out if a specific gene or a group of genes makes a person more susceptible to getting the disease. What is still unknown is what causes those changes to happen.