Protection:\xa0As it covers the entire body surface, it is the first line of defence against any kind of mechanical injury, chemical exposure, excessive fluid loss and infections. Ciliary projections present in the nose or upper respiratory tract, trap the dust particles and prevent it from entering the bodyAbsorption:\xa0The epithelial lining of the digestive tract absorbs water and nutrientsExchange of substances:\xa0Epithelial tissue regulates the exchange of substances between body and external environment as well as the internal exchange between different parts of the body. Everything that enters the body or enters the bloodstream by absorption has to cross the epithelial barrierSensation:\xa0Sensory receptors are present in the epithelial tissue of the nose, eyes and ears, taste bud, etc. that help in transmitting signals from the external stimuli to the brainSecretion:\xa0Various glands made up of epithelial cells secrete hormones, enzymes, saliva, mucus, sweat, etc.