Structure and Function
Colorectal cancer

The colon and rectum are parts of the digestive, or gastrointestinal (GI), system. The purpose of this system is to break down food, absorb nutrients and water, and remove waste from the body.

Food matter is largely broken down in the stomach and then released into the small intestine. Most of the nutrients from food are absorbed in this region of the digestive system. The small intestine continues into the colon, or large intestine, which is divided into 4 regions (based on location): ascending colon, transverse colon, descending colon, and sigmoid colon

The main purpose of the colon is to absorb water and mineral nutrients from the food matter and store waste. Waste moves from the colon into the final 6 inches of the digestive system, called the rectum, and passes out of the body through the anus.