What is the primary cause for the abnormal distention of airspaces in emphysema?

The primary cause for the abnormal distention of airspaces in emphysema is the destruction of alveoli walls. In emphysema, the alveoli, which are the small air sacs in the lungs, become damaged and lose their elasticity. This damage often results from smoking or prolonged exposure to irritants, leading to the breakdown of the elastic fibers and structural integrity of the alveolar walls.

As these walls break down, the surface area available for gas exchange decreases, and the remaining alveoli may enlarge, leading to air trapping and distention. The result is difficulty in exhaling air from the lungs, a hallmark symptom of emphysema. This impairment in lung function contributes significantly to the characteristic symptoms of the disease, such as shortness of breath and a chronic cough.

Factors like fluctuating blood pressure, viral infections, or poor nutrition may impact overall lung health, but they do not directly cause the structural changes to alveoli seen in emphysema. Therefore, the destruction of alveoli walls is the defining mechanism behind the condition's pathology.