ABSTRACT
The vascular beds of the nose, trachea, and bronchi show some structural similarities but also considerable differences. Control of the airway vascular beds, including by neuropeptides, has not only pharmacological and physiological interest, but clinical significance. With physiological nervous control, the balance of parasympathetic and sympathetic motor activities may be crucial. A common feature of the vascular anatomy of all parts of the airways is a subepithelial capillary plexus. The capillary network drains into postcapillary venules, which, unlike the capillaries, have smooth muscle in their walls as a discontinuous sheet. The bronchial vasculature has a complex system of anastomoses with the pulmonary blood vessels, and probably 75% of the bronchial blood flow drains into the pulmonary vascular bed. The nasal mucosa has an exceptionally well-developed system of capacitance vessels or sinuses. The lower airways also possess a vascular capacitance system, but this is less well developed than in the nose and shows striking species differences.
