Epithelia are formed of cells that line the cavities around the body and cover many of the flat surfaces on our body. For example, our hand wouldn't be as smooth as it is without the millions of epithelial cells lining the skin. Epithelial cells can join together to form epithelial membranes and tissues, called epithelium. These are vital in our day to day functioning and allow us to live the way we do, helping us survive. There are several functions that the epithelial tissue performs, with the primary function being to protect. However, it’s also involved in filtration, secretion and absorption within the human body.
Epithelial cells are stuck together in sheets of tissue called epithelia. The sheets are held together by different types of interactions and gap junction. One junction is the tight junction, which is considered the closest junction in the world. Epithelium is given support on the base of the cell by a basement membrane called the basal lamina. This lies on the capillary bed, which provides epithelia with enough nutrients and disposal of waste products.
One of the main function of epithelial cells are to protect. The skin, which is covered by the cells, protect the body from invasion of germs and harmful bacteria, preventing infection and other illnesses. The cells also act as a barrier to sunlight and UV, protecting us from the dangers of the light and preventing skin cancer and skin burn. Another function of the cells is to filter our dirt and dust particles from our body, helping us keep cleaner and fresher both internally and externally. In addition to this, they are involved in the process of secretion. Epithelial cells form glands of the body, which secrete hormones and enzymes around the body, helping us function. However, they also have the ability to secrete wax, digestive enzymes and milk, further aiding us and other humans. Finally, they are involved in absorption, in which they absorb food and water, playing a huge part in the body's digestive system.
There are several different types of epithelial tissue: