Site of action of drugs in COPD. Top left lungs with the bronchial tree in transparency, from which a sub-segmental bronchus in zoom. A bronchiole sectioned on the left and normal. The right-sided bronchiole exhibits bronchoconstriction with hypersecretion of mucus, inflammatory cells producing cytokines in the mucosa. At the bottom the pulmonary lobules. On the left the alveolar sacs are normal, on the right, an emphysema seen in section shows the distended cells.