Final answer:
The visceral pleura covers the lung, the parietal pleura lines the thorax, and the intrapleural space between them reduces friction. Pleurisy is inflammation of these tissues that can cause increased pressure and decreased lung volume.
Step-by-step explanation:
Each lung is surrounded by an invaginated sac. The visceral pleura is the layer of tissue that covers the lung and dips into spaces, while the parietal pleura lines the interior of the thorax. The space between these layers is called the intrapleural space and contains a small amount of fluid that reduces friction during lung contraction and relaxation. Inflammation of these tissue layers, known as pleurisy, can increase pressure and reduce lung volume.