Work of the Large Intestine

The human large intestine is about 6 feet (2 meters) long. It includes the ascending colon, …
The large intestine is made up of the ascending colon, transverse colon, descending colon, rectum, and anus. In the large intestine water is reabsorbed through the intestinal wall, converting the remaining waste into solids that are passed from the body as feces. The colon is populated by bacteria that digest any remaining food products. These bacteria also produce folic acid, which prevents anemia, and other vitamins.
Peristalsis moves digested material from the small intestine into the ascending colon through a sphincter muscle, which prevents their return into the small intestine. In the ascending colon, fluids and salts are absorbed. In the transverse colon more water is removed from the waste materials until they are in solid form.
The descending colon is a holding area for solid waste. When the body is ready to eliminate this material, it moves into the rectum, the last 5 to 6 inches (13 to 15 centimeters) of the descending colon. When enough waste material accumulates, it is eliminated through the anus—the open end of the rectum—as feces. A sphincter at the edge of the anus prevents fecal material from leaving the body involuntarily.
Peristalsis in the large intestine is much slower than in other parts of the digestive tract. The large intestine in humans is only about 6 feet (2 meters) long, yet waste material takes 10 to 20 hours to pass through it.