Dictionary of Allergies .. Bronchial epithelial cilia,

Mucociliary clearance is an important primary innate defense mechanism that protects the lungs from deleterious effects of inhaled pollutants, allergens, and pathogens. Mucociliary dysfunction is a common feature of chronic airway diseases in humans. The mucociliary apparatus consists of three functional compartments, that is, the cilia, a protective mucus layer, and an airway surface liquid (ASL) layer, which work in concert to remove inhaled particles from the lung [1].

The transport and removal of bronchial secretions is normally accomplished by the cilia of the bronchial epithelium. Of most importance for mucociliary transport is the regular and coordinated ciliary beat. Ciliated cells constitute the major structural element of the surface epithelium throughout the respiratory tract down to about the level of the terminal bronchiole where ciliated cells are normally no longer present or infrequent. The surface of these cells is uniformly covered with microvill and cilia. The microvills, by increasing the surface area of the cell, presumably subserve the function of fluid resorption from the swol phase of the secretory layer into the epithelial cell. Cilia normally beat at a frequency of 12-14 Hz, in the sol phase of the secretory layer, with a whip-like motion. During the active or effector phase of the beat cycle, only their tips enter the gel phase and thus actually transport airway secretions over the epithelial surface towards the pharynx[2].

References

1.Mall MA. Role of cilia, mucus, and airway surface liquid in mucociliary dysfunction: lessons from mouse models. J Aerosol Med Pulm Drug Deliv. 2008 Mar;21(1):13-24.

2. Morgenroth, K., Wettengel R., Newhouse, M.: Bronchial Asthma. Boehringer Ingelheim. GmbH 1987.