The pleura is a membrane that covers the two lungs , made up of two sheets , called pleural sheets . These are distinguished in the parietal pleural sheet (or parietal pleura) and in the visceral pleural sheet (or visceral pleura). The former covers the lungs externally by dividing them from the chest wall, while the latter wraps the inner surface of the lung . The pleura has a serous composition.
What is the pleura?
It is the serous membrane that lines the lungs. The parietal and visceral pleural sheets are always in mutual contact, and slide over each other thanks to the presence of a thin film of pleural liquid, which is placed in the space between them. The existence of this thin film is necessary to allow the lungs to perform the movements of the muscles to which they are united during breathing. The two sheets delimit a virtual cavity, the pleural cavity . Negative pressure takes place in the pleural cavity which allows the lungs to expand upon inspiration, as this cavity does not communicate with the outside or with other organs.
The top of the parietal pleural leaflet is called the pleural dome : it is located right at the supraclavicular bone and corresponds to the apex of the lung.
On the histological level, the pleura is considered as a mesothelium , that is, a tissue that maintains typical properties of both endothelium and epithelium and which, therefore, resembles both one and the other. Endotheliums are the thin tissue that internally delimits the lumen in the blood or lymphatic vessels , while epithelia are the tissues that cover the external surface or cover the internal cavities of the body.
What is the pleura for?
The pleura allows the movement of the lungs on the walls of the lung cavity and therefore allows the expansion of the lungs at the moment of inspiration