What role does the pleural cavity play in lung function?

• A. Facilitates gas exchange
• B. It acts as a barrier to pathogens
• C. It reduces friction and aids lung expansion
• D. It stores excess air

Answer: (C)

The pleural cavity is a thin fluid-filled space that exists between the two pleurae, which are membranes surrounding the lungs. Its primary function is to reduce friction between the lungs and the chest wall during respiration. As the lungs expand and contract with each breath, the pleural fluid allows for smooth movement, minimizing wear and tear on the lung tissue and the thoracic cavity.

Furthermore, the pleural cavity plays a crucial role in creating negative pressure relative to the atmospheric pressure. This negative pressure is essential for lung expansion during inhalation; it helps draw air into the lungs by expanding the thoracic cavity.

While the pleural cavity does not directly facilitate gas exchange, store air, or serve as a barrier to pathogens, its role in reducing friction and enabling efficient lung expansion is essential for proper ventilation and air movement into the alveoli, where gas exchange occurs.