The shape of the stomach is similar to the hanging curved pepper (curved to the right), the upper end is the entrance of the stomach called the cardia, the lower right end is the exit of the stomach called the pylorus, the upper part is called the fundus, the middle is called the gastric body, the lower part is called the gastric sinus, the right side is shorter called the gastric less curved, the left side is longer called the gastric greater curved, the side to the abdominal wall is called the anterior wall of the stomach, the side to the back is called the posterior wall of the stomach. The stomach wall from inside to outside (or shallow to deep) consists of the gastric mucosal layer (mainly mucosal epithelial cells), submucosal layer, muscular layer, subplasma layer and plasma layer. The main functions of the stomach are: 1) to store, grind, mix, and empty food into the small intestine; 2) to partially digest food by secreting gastric acid and various digestive enzymes; and 3) to produce internal factors that promote the maturation of red blood cells (a lack of which predisposes to anemia). The adjacent structures of the stomach include the esophagus above the cardia, the duodenum below the pylorus, the pancreas below the lower middle of the stomach posteriorly, the transverse colon below the lower middle of the stomach, the liver above the right side of the gastric lesser curvature/pylorus/cardia, the posterior abdominal wall behind the posterior gastric wall, the spleen behind the left side of the upper middle of the stomach, the diaphragm and left lobe of the liver above the fundus, the abdominal wall in front of the stomach, the adrenal glands/kidneys behind the body junction of the fundus, and the small intestine below the anterior part of the greater curvature of the gastric body.