Nasal cavity is the first part of respiratory system contacted with atmospheric air. Functions of the nasal cavity include varming, humidification and filtration of pollutant particles from inspired air, participation in reflex and nonreflex defensive mechanisms of the airways, immunological surveillance of inspired air, smelling and modulation of the voice. Inappropriate reaktivity of the structures of nasal mucosa is manifested as a nasal hyperreactivity. These mechanisms play an important role in the pathogenesis of allergic and nonallergic rhinitis. There are several theories, which discuss mechanisms responsible for increased reaktivity of nasal mucosa. These mechanisms include increased epithelial permeability and enhanced senzitivity of nerve endings in nasal mucosa, mediator release after nonspecific stimuui and increased number and/or senzitivity of cell membrane receptors. These mechanisms affect not only the function of nasal cavity, but clinical and experimental studies provided valid evidence, tkat disorders of nasal cavity and sinuses have strong influence on lower airway functions, especially in relation to chronic cough, bronchitis and bronchial asthma.

        Key words: physiology of nasal cavity, nasal reaktivity, nasal hyperreactivity