The stomach is comprised of squamous epithelial tissue cells and smooth muscle. In location, the stomach holds its place in the upper abdomen, on the left side of the human body. During consumption, food finds its way via the esophagus and the lower esophageal sphincter to reach the stomach.
The stomach is considered an exocrine gland because it secretes enzymes, along with stomach acid, to decompose a food source. The inner ridges of the stomach lining are known as rugae, which are involved in muscle contractions used to promote digestion. After digestion, food finds its way through another valve, the pyloric sphincter, into the small intestine for passage via the excretory system.