Various lung diseases exhibit distinct histological changes. For instance, in chronic obstructive pulmonary disease (COPD), there is often destruction of alveolar walls and enlargement of airspaces (emphysema). In asthma, the bronchi and bronchioles show thickening of the basement membrane, increased smooth muscle mass, and infiltration by inflammatory cells. In pneumonia, alveoli may be filled with inflammatory exudate, impairing gas exchange.
