Airway receptors

There are many types of afferent receptor in the airways; at least five in the larynx: pressure, drive, cold, irritant and C-fibre; and at least four in the trachea and bronchi: slowly and rapidly adapting stretch receptors ( SARs and RARs), C-fibre receptors, and those in neuroepithelial bodies (NEB s). Histologically enough sensory structures have been identified to accoun t for the various patterns of afferent activity, but most correlations are poor. For the larynx, four or more sensory structures have not definitively been identified with afferent discharges and reflex responses. For the tra chea and bronchi, only SARs have been clearly identified morphologically an d physiologically. The reflexes and afferent discharges from RARs and C-fib re receptors are fairly clear, some at least of the sensory terminals lie i n the epithelium, but receptor complexes have not been mapped out. Nerves i n NEBs have been identified, but not their local and central reflex actions . (C) 2001 Elsevier Science B.V. All rights reserved.