What is the primary function of the visceral pleura?

The primary function of the visceral pleura is to protect the lung surface. This thin membrane directly covers the lungs, serving as a protective barrier against physical damage and infection. Additionally, the visceral pleura secretes pleural fluid, which plays a crucial role in reducing friction between the lungs and the chest wall during respiration. This fluid creates a moist environment that allows the lungs to expand and contract smoothly as air is inhaled and exhaled.

While the options regarding lung expansion and gas exchange might seem relevant, their primary functions are addressed by other anatomical structures. Lung expansion is facilitated by the mechanics of the thoracic cavity and diaphragm during respiration, whereas gas exchange occurs in the alveoli of the lungs. Thus, the primary protective role of the visceral pleura is its critical function in maintaining lung health and integrity.