The anatomy of the stomach may be modified, or the stomach may be bypassed entirely. Surgical removal of the stomach is called a gastrectomy, and removal of the cardia area is a called a cardiectomy. "Cardiectomy" is a term that is also used to describe the removal of the heart. A gastrectomy may be carried out because of gastric cancer or severe perforation of the stomach wall. Fundoplication is stomach surgery in which the fundus is wrapped around the lower esophagus and stitched into place. It is used to treat gastroesophageal reflux disease (GERD). History
There were previously conflicting statements in the academic anatomy community over whether the cardia is part of the stomach, part of the oesophagus or a distinct entity. Modern surgical and medical textbooks have agreed that "the gastric cardia is now clearly considered to be part of the stomach." Etymology
The word stomach is derived from the Latin stomachus which has roots from the Greek word stomachos (στόμαχος), ultimately from stoma (στόμα), "mouth". Gastro- and gastric (meaning "related to the stomach") are both derived from the Greek word gaster (γαστήρ, meaning "belly"). Other animals
Although the precise shape and size of the stomach varies widely among different vertebrates, the relative positions of the oesophageal and duodenal openings remain relatively constant. As a result, the organ always curves somewhat to the left before curving back to meet the pyloric sphincter. However, lampreys, hagfishes, chimaeras, lungfishes, and some teleost fish have no stomach at all, with the oesophagus opening directly into the intestine.
The stomach is surrounded by parasympathetic (stimulant) and sympathetic (inhibitor) plexuses (networks of blood vessels and nerves in the anterior gastric, posterior, superior and inferior, celiac and myenteric), which regulate both the secretory activity of the stomach and the motor (motion) activity of its muscles. Because it is a distensible organ, it normally expands to hold about one litre of food. The stomach of a newborn human baby will only be able to retain about 30 millilitres. The maximum stomach volume in adults is between 2 and 4 litres. Sections
In classical anatomy the human stomach is divided into four sections, beginning at the cardia. The cardia is where the contents of the oesophagus empty into the stomach. The fundus (from Latin bottom) is formed in the upper curved part. The body is the main, central region of the stomach. The pylorus (from Greek gatekeeper) is the lower section of the stomach that empties contents into the duodenum.The cardia is defined as the region following the "z-line" of the gastroesophageal junction, the point at which the epithelium changes from stratified squamous to columnar. Near the cardia is the lower oesophageal sphincter. Research has shown that the cardia is not an anatomically distinct region of the stomach but a region of the oesophageal lining damaged by reflux. Anatomical proximity
The stomach bed refers to the structures upon which the  stomach rests in mammals.