Answer
Pleurisy is inflammation of the parietal and visceral pleurae, the membranes which line the thoracic cavity and the lungs. When these membranes are inflamed, their surfaces become rough, causing them to stick and drag across one another each time the lungs inflate or deflate with air. This sticking and dragging of the membranes causes each breath to be painful.
Work Step by Step
When serous membranes are inflamed, their normally smooth surfaces become roughened. This roughness causes the organs to stick together and drag across one another, leading to excruciating pain (Page 19).
