The stomach is a four-part organ with two openings (esophageal and duodenal) and two apertures (esophageal and duodenal) (cardia, fundus, body, and pylorus).
The fundus absorbs digestive gases, the body secretes pepsinogen and hydrochloric acid, and the pylorus secretes mucus, gastrin, and pepsinogen.
There are five main functions of the stomach: food storage on a temporary basis, control of the amount of food that enters the duodenum, antibacterial activity and acid secretion stomach fluidization, preliminary digestion with pepsin, lipases, and other enzymes.