Most of the digestion process takes place in the small intestine. It receives digestive enzymes from the pancreas and bile salts from the liver, which both play very important parts in this part of the digestion. The small intestine acts in the wave method as the oesophagus, the stomach and the large intestine. Digestive juices such as the enzymes are leaked from its walls. These juices help the digestive juices from the pancreas (pancreatic juice) and bile from the gall bladder to finish the rest of the digestion processes.
The food molecules are absorbed through the walls of the small intestine and into the blood, which transports to the liver for processing. These simple molecules include glucose (from carbohydrate digestion), amino acids (from protein digestion) and fatty acids (from fat digestion). The sludgy remains of undigested food are then squeezed out of the small intestine and into the large intestine.
An adult small intestine is 7 metres (22 feet) long.