Caption

Large intestine. Coloured barium X-ray of the abdomen showing a healthy large intestine (brown), the final section of the digestive tract. Its main segment, the colon, runs up and then to the right from lower left, eventually descending to meet the rectum (pale area, lower centre). The intestine provides a large surface area for the absorption of water, vitamins and mineral salts, and produces mucus to assist faecal movement and to protect its wall from mechanical damage. This is an air, or double, contrast barium enema. Water containing radio-opaque barium sulphate powder was introduced into the colon, which was then distended by air.