Final answer:
The pleura reduces friction during breathing movements.
Step-by-step explanation:
The pleura is a membrane that encloses the lungs and lines the thoracic cavity. It is composed of two layers: the visceral pleura, which covers the surface of the lungs, and the parietal pleura, which lines the thoracic cavity. The pleura produces pleural fluid, which acts as a lubricant between the two layers, reducing friction during breathing movements.
The main role of the pleura in respiration is to reduce friction during breathing movements. As the lungs expand and contract during inhalation and exhalation, the pleural fluid allows the two layers of the pleura to slide smoothly against each other. This helps to prevent trauma and damage to the delicate lung tissues.