Partially digested and undigested moves through the sphincter of the stomach into the small intestine. The small intestine area with the absorption of nutrients, increasing the surface area of the small intestine is the part that extends up in the intestinal tube-like fingers around 4-5 million a called Villi. The outer skin of the villi extending called Microvilli. As a result, the efficiency of absorption of the small intestine is very high. The most interesting small intestinal absorption of nutrients and the duodenum portion of vitamins almost every type is about 25 centimetres long, jejunum absorb fat approximately 2.5. cm and Ileum absorption of vitamin B12 of about 4 meters long and bile salts by Osmosis Facilitated Diffusion Processes and Active transport. When food from the stomach into the small intestine, the duodenum, pancreas creates a hormone to stimulate the creation of sodium hydrogen carbonate, which is a mighty bass released into the duodenum to reduce the acidity of the food.