ABSTRACT

INTRODUCTION Sensory nerves monitor the status of the nasal mucosal microenvironment to (i) initiate immediate protective mucosal responses via the axon response mechanism, (ii) recruit brain stem reflexes including locally active parasympathetic exocytosis and systemically active sympathetic vasoconstrictor reflexes, (iii) modulate the work of breathing, and (iv) notify cerebral mucosal sensory centers (e.g., insula, secondary somatosensory cortex) of the conditions of inhaled air. These integrated reflexes regulate epithelial, vascular, glandular, smooth muscle, and inflammatory protective defenses (1,2).