The pulmonary vasculature involved in gas exchange includes pulmonary arteries and arterioles that bring blood relatively low in oxygen and high in carbon dioxide from the heart to the gas exchange areas, alveolar capillaries where the gas exchange occurs, and pulmonary venules and veins that return oxygenated blood to the heart. Bronchial arteries and veins are part of the systemic circulation and provide oxygen and nutrients to the bronchi.

Pulmonary arteries branch into increasingly smaller vessels accompanying the bronchi and bronchioles, often with a common connective-tissue sheath (bronchovascular bundle), and have a cross-section diameter approximately equal to that of the accompanying airway. Gas exchange occurs in capillaries in the alveolar septa, and venules merge into increasingly larger veins that return oxygenated blood to the heart. Veins are found in the interlobular septa and pleura.

The large branches of the pulmonary artery are elastic arteries, although the elastic fibers are more fragmented than in the aorta. The elastic pulmonary arteries give rise to the muscular pulmonary arteries that accompany the bronchioles. Arteries have two elastic lamina, but smaller arterioles often have only one elastic lamina. Veins also have only one elastic lamina. Histologic differentiation of venules from arterioles may be very difficult.

Lymphatic channels are found in the bronchovascular bundles, in the interlobular septa, along pulmonary veins, and in the pleura. Lymphatics are generally histologically inconspicuous. Certain diseases, such as sarcoidosis, tend to be distributed along lymphatics (lymphangitic distribution).