What is the function of the pleurae in the respiratory system?

The pleurae serve an important function in the respiratory system by forming an envelope that encases the lungs and separates them from the chest wall. This double-layered serous membrane consists of two parts: the visceral pleura, which directly covers the lungs, and the parietal pleura, which lines the chest cavity.

This arrangement allows for a frictionless surface that facilitates smooth movement of the lungs during respiration. When the lungs expand and contract, the pleural layers help to maintain negative pressure in the pleural cavity, which is essential for lung inflation. Moreover, the pleurae help to prevent any direct contact between the lung tissue and the thoracic wall, which contributes to overall lung protection and function.

In terms of other options, while the pleurae provide support through their structural role, they do not actively support lung structures in the same manner as ligaments or other supporting tissues. They do not have a direct role in gas exchange or in controlling airflow; these functions are primarily managed by alveoli and the bronchial structures, respectively.