A disease characterized by a collapsed or airless condition of the lungs is...

• A. Pulmonary edema.
• B. Atelectasis.
• C. Emphysema.
• D. Pneumonia.

Answer: (B)

Atelectasis is the condition where part of the lung collapses or does not fill with air, creating an airless region. It happens when alveoli lose air due to airway obstruction, external compression, or insufficient surfactant, and it reduces the volume of the affected lung segment and impairs gas exchange. Pulmonary edema involves fluid buildup in the lungs, not a collapsed airless state. Emphysema features destruction of alveolar walls and enlargement of air spaces with overall hyperinflation, not collapse. Pneumonia involves infection that fills alveolar spaces with inflammatory exudate, leading to consolidation rather than simple collapse. Therefore, the description matches atelectasis.