Pleura

German: Lungskin, is a special skin that covers the chest from the inside (pleura parietalis) and the lungs from the outside (pleura visceralis). It's made up of an epithelium that's a the fluid out. This liquid ensures that the two skins are movable against each other. This displacement is necessary for the function of respiration, since the lung is enlarged by the negative pressure between the pleura visceralis and the thorax when the thorax is enlarged.