Emphysema Permanent enlargement of air spaces distal to terminal bronchiole, resulting from breakdown of their walls. This results in decreased surface area for gas exchange and decreased numbers of alveolar capillaries with pruning of the pulmonary arterial tree.
Classification is by lobar distribution and lobular pattern.
Most commonly caused by cigarette smoking and pneumoconiosis. In panacinar type, proximal and distal parts of unit are involved, mostly in lower lobar zones, especially of lower lobes. Chronic Bronchitis Small bronchi and bronchioles undergo metaplasia with increased numbers of mucus-secreting goblet cells and chronic inflammation, leading to fibrosis of the alveolar walls. There is increased responsiveness to stimuli, including inhaled agents, causing paroxysmal bronchial airway smooth muscle constriction. The small bronchi and bronchioles are occluded by inflamed mucus plugs containing numerous eosinophils.