The colon and rectum make up the large intestine (or large bowel), which is part of the digestive system, also called the gastrointestinal (GI) system (see illustration below). 
The colon and rectum make up the large intestine (or large bowel). Which is part of the digestive system, also called the gastrointestinal (GI) system which breaks down and absorbs the food/liquids that you eat. (see illustration below). 