Where are the colon and rectum? what do they do, exactly?

Lower intestine: The colon and rectum are the lower end of the gastrointestinal (GI) tract that starts in the mouth. The colon's main function is to absorb water, although a variety of other subtances may be absorbed through the colon, as well. It acts as a reservoir function so that most people have only 1 or 2bm's each day. The rectum is the lowest end. It has muscles and nerves that give bowel control.

LGI anatomy lesson: The colon (large intestine) is the last five feet of the GI tract. Simplistically, the right colon scavenges water to prevent dehydration, the left colon stores solid waste. The rectum samples intestinal contents, assists in stool continence, and through a series of coordinated neurologic steps permits colonic emptying.