Epithelial cells are a group of tightly compressed cells that layers itself on the internal and external surfaces of bodily organs and other surfaces found in the body. As a collective term, these cells are also referred to as a tissue called epithelium. These cells are also the primary composition of human skin.
The basic function of epithelial cells is to provide a protective layer for the organ they enclose. Cells of this type in the digestive system also can absorb nutrients that the body needs during the digestion process. They can also aid in the secretion of enzymes and hormones, as well as the excretion of unwanted byproducts, especially when located in areas such as the kidneys and sweat glands. Epithelial linings along the lungs help disseminate the oxygen in all parts of bodies. Special epithelial tissues around the sense organs such as the eyes, nose and tongue are made with nerve endings to heighten sensitivity.
These cells are categorized as either lining or glandular ephithelium cells. Lining epithelials further protect the organs by coating the cell’s basement membrane, another protecting sheet that prevents foreign bodies from invading the healthy organs. Glandular epithelial cells, on the other hand, coat the glands, such as the sweat and mammary glands.
Lining epithelial cells are further classified as simple or stratified epithelials. The simple type has only one layer of cells, and the stratified kind is composed of several cell layers, ranging from three to seven layers. Stratified cells are usually found on organs that can experience heavy attacks from chemical reactions or foreign bodies, such that the organs are not affected even if one layer of epithelial cells is destroyed. An epithelial cell can also take various shapes, depending on its location and function: flat, cube-like or column-shaped.
Epithelial cells are usually constructed to not have any blood vessels, so no physical pain is experienced when they are exfoliated and regenerated constantly, not just from the skin, but from all organs that have epithelia. Urine can be a vehicle for these cells to be excreted out of the body, which is why it is normal for these cells to be microscopically observed during urinalysis. Elevated amounts of epithelial cells, however, can indicate problems such as bladder or urinary tract infection. Urine that is unusually cloudy and darker-colored might cause some concerns and a need for a thorough urinalysis.