In the small intestine, the digestive process is completed on the partly digested food by pancreatic juice, intestinal juice and bile. The pancreatic juice is produced by the pancreas and pours into the small intestine through a tube or duct. The intestinal juice is produced by the walls of the small intestine. It has milder digestive effects than the pancreatic juice but carries out similar digestion. Bile is produced in the liver, stored in the gallbladder, and flows into the small intestine through the bile duct. When the food is completely digested, it is absorbed by tiny blood and lymph vessels in the walls of the small intestine. It is then carried into the circulation for the nourishment of the body. Food particles are small enough to pass through the walls of the intestine and blood vessels only when they are completely digested.
The small intestine is about 7m (7.6 yards) long and is lined with small finger-like protuberances called villi. The successful absorption of nutrients depends on their transport away from the cells of the villi into the bloodstream.