What is the role of the pleura in the respiratory system?

The pleura are a set of membranes that surround the lungs and line the thoracic cavity. Their primary role is to provide lubrication for lung movement during respiration. This lubrication comes from pleural fluid, which is located between the parietal pleura (lining the thoracic cavity) and the visceral pleura (covering the lungs). This fluid reduces friction as the lungs expand and contract with each breath, allowing for smooth movement against the rib cage and other structures in the thoracic cavity.

Additionally, the pleura help maintain pressure differentials that are critical for effective lung inflation and deflation. This aspect of lung mechanics is essential for optimal breathing efficiency. While the other options may relate to functions of the respiratory system, they do not accurately reflect the specific role of the pleura. For instance, vocalization is primarily supported by the larynx, gas exchange occurs in the alveoli, and air filtration is mainly a function of the nasal passages and upper airway structures.