What is the function of the pleura?

The pleura plays a crucial role in the respiratory system by surrounding the lungs and serving as a protective barrier. This double-layered membrane consists of the visceral pleura, which is attached to the lungs, and the parietal pleura, which lines the thoracic cavity. The space between these two layers, known as the pleural cavity, is filled with pleural fluid.

The primary function of this fluid is to reduce friction between the lung surfaces and the chest wall during the breathing process. As the lungs expand and contract, the pleura allows for smooth movement, preventing irritation and damage that could arise from tissue rubbing against each other. Additionally, the negative pressure within the pleural cavity helps to keep the lungs inflated and plays a role in the mechanics of respiration.

The other options do not accurately describe the function of the pleura. Storing oxygen, producing mucus, and filtering blood are functions associated with other organs and systems in the body, but not with the pleura.