Which one of the following statements about pleural fluid and the pleural cavity is incorrect?

• A. Pleural fluid reduces friction between the pleurae during breathing.
• B. Pleural fluid helps maintain surface tension, preventing lung collapse.
• C. The pleural cavity is located between the visceral and parietal pleurae.
• D. The pleural cavity is a real space filled with a large volume of fluid.

Answer: (D)

Verified step by step guidance

1. Understand the role of pleural fluid: Pleural fluid is a lubricating fluid that reduces friction between the pleurae (visceral and parietal) during breathing, allowing the lungs to move smoothly within the thoracic cavity.
2. Recognize the function of surface tension: Pleural fluid helps maintain surface tension, which is crucial for keeping the lungs inflated and preventing lung collapse (atelectasis).
3. Identify the location of the pleural cavity: The pleural cavity is the potential space between the visceral pleura (covering the lungs) and the parietal pleura (lining the chest wall).
4. Clarify the nature of the pleural cavity: The pleural cavity is not a 'real' space filled with a large volume of fluid; instead, it is a potential space with a small amount of pleural fluid to facilitate movement and maintain surface tension.
5. Evaluate the statements: Based on the understanding of pleural fluid and the pleural cavity, identify that the incorrect statement is the one suggesting the pleural cavity is a real space filled with a large volume of fluid, as it is actually a potential space with minimal fluid.