The stomach is a portion of the digestive tract. It is located in the upper and middle part of the abdomen, called the epigastric region, between the esophagus and the duodenum. This pouch-like organ is divided into three parts: the fundus, the body of the stomach and the antrum. The wall of the stomach is made up of several layers: the mucous membrane or inner surface layer of the stomach, the submucous membrane that supports the mucous membrane, the muscular layer called muscularis and the serosa or outer layer of the stomach. 

The stomach ensures the digestion of food by its mechanical and chemical functions. In the stomach, food is stirred and mixed with gastric juices which are a mixture of water, hydrochloric acid and enzymes. The processed food is called chyme. The chyme is then sent to the duodenum through the pylorus. It is in the duodenum that the acidic chyme is neutralized by the bases from the bile and pancreatic juice.