<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> The intestinal epithelium is the layer of cells that forms the luminal surface or lining of both the small and large intestine (colon) of the gastrointestinal tract . It is composed of simple columnar epithelium . It has two important functions: absorbing helpful substances and providing a barrier against harmful substances . Some diseases and conditions are caused by dysfunction in the intestinal epithelium, and some diseases and conditions cause problems with these cells, which then leads to further complications . </P> <P> The epithelium is part of the intestinal mucosa layer . The epithelium is composed of a single layer of cells . The other two layers of the mucosa, the lamina propria and the muscularis mucosae, support and articulate the epithelium layer . To securely contain of the contents of the intestinal lumen, the cells of the epithelial layer are joined together by tight junctions thus forming a contiguous and relatively impermeable membrane . </P>

Role of epithelial tissue in the digestive system