Which term describes a collapsed lung?

• A. Atelectasis
• B. Hyperpnea
• C. Pleural effusion
• D. Emphysema

Answer: (A)

Collapsed lung means the lung tissue has deflated and lost air, reducing the area available for gas exchange. This condition is called atelectasis. It can happen when airways are blocked, when fluid or pressure in the pleural space compresses the lung, or when the lung deflates due to a puncture. Hyperpnea is just deeper or faster breathing, not lung collapse. Pleural effusion is fluid in the pleural cavity that can limit expansion but isn’t the collapse itself. Emphysema involves destruction of alveolar walls and overinflated air spaces, not a collapsed lung.