What are the airtight membranes that cover the outer surface of the lungs and line the chest wall called?

The correct answer is pleurae. The pleurae are thin, double-layered membranes that encompass the lungs and provide a protective layer. They consist of two main parts: the visceral pleura, which adheres to the surface of the lungs, and the parietal pleura, which lines the inner surface of the chest wall. This structure allows for the smooth movement of the lungs during breathing and plays a crucial role in respiratory mechanics.

The pleurae also help create a pleural cavity filled with pleural fluid, which reduces friction between the lung surfaces and the chest wall, facilitating breathing. Understanding the function and importance of the pleurae is essential for grasping concepts related to respiratory health and physiology.