Losing the normal negative pressure can cause what to happen to the lungs?

• A. Lungs partially or fully collapse
• B. Lungs become overinflated
• C. Lungs remain unaffected
• D. Lungs fill with blood

Answer: (A)

Losing the normal negative pressure in the pleural space removes the suction that keeps the lung expanded against the chest wall. Without that suction, the transpulmonary pressure drops toward zero and the lung’s elastic recoil causes it to deflate, leading to partial or complete collapse (atelectasis). So the lung can partially or fully collapse when negative intrapleural pressure is lost. The other options don’t fit because overinflation would require more negative pressure, not its loss; the lungs wouldn’t remain unaffected; and filling with blood isn’t a direct result of changing pleural pressure.