Final answer:
Emphysema is a lung condition that causes enlargement of air spaces and destructive changes in alveolar walls, often a result of smoking, which leads to decreased gas exchange in the lungs.
Step-by-step explanation:
The anatomic alteration of lungs characterized by air space enlargement distal to terminal bronchioles and destructive changes to alveolar walls is known as emphysema. This lung disease is often caused by smoking, leading to the breakdown of the walls of the alveoli, and consequently, reduced gas exchange capability in the lungs. The alveolar macrophages in the alveoli help remove debris and pathogens, but significant damage from emphysema impedes their function, contributing to alveolar dead space where gas exchange cannot effectively take place.