Chemical digestion occurs in the duodenum.
The gall bladder stores bile which, when released into the duodenum, is a chemical emulsifier of fat (breaks fat into tiny droplets).
The pancreas releases pancreatic juice which has a number of catabolic enzymes in it. The enzymes break apart proteins and starches. In addition, the juices help neutralize the acid from the stomach.
The low pH of the stomach, due to hydrochloric acid, is neutralized by the alkalinity of bile and pancreatic juice.
The surface area of the duodenum is increased by the presence of villi which are tiny finger-like projections that protrude into the lumen (opening inside the tube) of the duodenum.
