The inner surface of stomach is lined by Gastric epithelium and that of the small intestine is lined by Intestinal epithelium. Both the gastric epithelium and intestinal epithelium are simple columnar, non-ciliated epithelial tissue.
Epithelium is a type of animal tissue that lines the inner surface of several organs in the body. In fact, the word Epithelium finds its origins from the Greek words “Epi” (that means on/onto) and “theli” (that means a tissue).
Simple columnar epithelium is single layered, column-shaped epithelium. Non-ciliated means the cells of this tissue lack a Celia. However, in the case of small intestine, microvilli are present that are nothing but finger like extensions of the epithelial cells (aiding absorption of the food by increasing surface area).
Most of the functions that the stomach (secretion of digestive juices) and small intestines (selective absorption) perform are actually carried out by this Epithelium.