What is a main feature of emphysema?

Emphysema is primarily characterized by the destruction of the alveolar walls, which are the tiny sacs in the lungs where gas exchange occurs. This destruction leads to a decrease in the surface area available for oxygen and carbon dioxide exchange, resulting in difficulty breathing and reduced oxygen supply to the body.

The loss of elasticity in the lung tissue also contributes to airflow limitation, as the airways collapse during exhalation, trapping air in the lungs. This condition is often related to long-term exposure to irritants such as cigarette smoke or environmental pollutants. While the other choices describe different respiratory issues, they do not accurately represent the primary pathological feature of emphysema, which is specifically the damage to the alveolar structure and subsequent respiratory impairment.