What is one of the primary functions of the pleurae in the respiratory system?

The primary function of the pleurae in the respiratory system is the reduction of friction. The pleurae consist of two layers, the visceral pleura that covers the lungs and the parietal pleura that lines the thoracic cavity. Between these two layers is the pleural cavity, which contains pleural fluid. This fluid serves to lubricate the surfaces of the pleurae, allowing the lungs to expand and contract smoothly during respiration without generating significant friction.

This reduction of friction is crucial because the lungs undergo continuous movement for inhalation and exhalation. Without the pleural fluid, the movement of the lungs against the thoracic wall would create excessive friction, leading to discomfort and potential injury to the lung tissue. Thus, the pleurae play a vital protective role in maintaining the efficiency and comfort of the respiratory process.