Healthy stomach. Coloured X-ray of the human stomach (blue) highlighted with barium meal. The stomach is a curved, sac-like organ that receives food from the oesophagus (not seen, top centre). The stomach plays a role in the initial digestion of food. Food then passes into the intestine. The glandular wall of the stomach appears as dots. Bones (green) of the spinal column and ribs are visible, with the pelvis at bottom. This image was produced by swallowing a barium meal, a substance opaque to X-rays and which shows up the structure of the digestive tract. Barium X-rays help to diagnose inflammation of the oesophagus or stomach, and detect stomach ulcers and bleeding.