The large intestine, appendix and rectum

After the food leaves the small intestine or small bowel, comes the large intestine or large bowel, also called the colon. It is wide, about 6 to 7 centimeters across, but shorter than the small intestine, at about 150 centimeters. It passes up the right side of the abdomen, across below the liver and stomach, down the left side, and then curves in an S shape to the lower abdomen.

The large intestine contains microbes known as gut bacteria. These gut bacteria break down certain kinds of food, especially plant foods, so the body can absorb the nutrients. The large intestine also absorbs much of the water from the leftover digested food, turning it into squishy brown lumps called faeces or bowel motions.

The appendix is a small part of the digestive tract, about the size of a little finger. It is the junction of the small and large intestines, in the lower right of the abdomen. The appendix is hollow inside and links to the main digestive tract, but does not lead anywhere else. It does not seem to have an important role.

At the end of the large intestine, the leftover and undigested contents called faeces pass into the last part of the main tract. This is the rectum which is about 15 centimeters long. The faeces stay here until it is convenient to remove them from the body. This is done by squeezing the muscles of the abdomen, to push the faeces through the loosened ring of muscle at the end of the tract, called the anus.