Which condition is characterized by permanent enlargement of air spaces beyond the terminal bronchioles due to alveolar wall thickening?

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

Answer: (B)

Emphysema is defined by permanent enlargement of air spaces distal to the terminal bronchioles, due to destruction of the walls of the alveoli and loss of elastic recoil. This destruction creates hyperinflated lungs with air trapping, reducing the surface area for gas exchange and increasing the work of breathing. Although some wording might mention wall thickening, the key idea is that the airspaces enlarge because the alveolar walls are destroyed, not thickened. Pneumonia involves infection with alveolar consolidation, pleurisy is inflammation of the pleura causing sharp chest pain, and pulmonary edema is fluid buildup in the lungs; none of these cause the characteristic permanent enlargement of distal air spaces seen in emphysema.