Answer:
5 - 15 ml
Step-by-step explanation:
The pleura is a delicate membrane that covers the lung from the outside (visceral pleura) and the inner surface of the chest wall (parietal pleura). Between the two pleurae, there is a very thin layer of fluid (between 5-15 mL) that facilitates the smooth sliding of the lungs into the rib cage when they fill and deflate air.
Pleural effusion, or water in the pleura, is characterized by excessive fluid accumulation in the space between the visceral pleura and the parietal pleura.