Reflexes initiated by activation of the vagal afferent nerves innervating the airways and lungs

Studies in animals and in humans have revealed an essential role for vagally derived bronchopulmonary afferent nerves in the regulation of homeostatic and defensive respiratory and autonomic reflexes. These reflexes are thought to protect the airways and lungs, optimize the work of breathing, maintain airway patency, and thus sustain adequate respiration in response to continually changing demands for gas exchange. The specificity and precision of respiratory and autonomic reflexes depends on the selective recruitment of airway vagal afferent nerve subtypes in response to a wide variety of physiologic and pathophysiologic chemical and mechanical stimuli. Once activated, these afferent nerves initiate stereotypical reflex responses that have facilitated their classification.