What is the potential space between the visceral and parietal pleura of the lungs called?

• A. Pleural cavity
• B. Mediastinum
• C. Alveolar space
• D. Pericardial space

Answer: (A)

The space between the lungs’ visceral pleura and the chest wall’s parietal pleura is the pleural cavity. It is a potential space that normally contains a small amount of lubricating pleural fluid, which lets the two surfaces slide smoothly during breathing. This fluid also helps create a slight negative pressure that helps keep the lungs expanded. If air or fluid fills this space, the lung can collapse or breathing can become difficult. The other structures mentioned are different: the mediastinum is the central compartment of the thorax housing the heart and great vessels, the alveolar space is inside the air sacs of the lungs, and the pericardial space surrounds the heart.