The Mucus Sheet on Respiratory Mucous Membrane

Abstract

The purpose of this paper is to emphasize the importance of the thin sheet of mucus which covers the mucous membrane of the respiratory tract. I shall confine my consideration to normal mucous membrane and the slight variation which may occur at the start of an acute cold. For several years I have thought that the value of constantly maintaining a mucus covering on the epithelium of the upper respiratory tract, especially that of the nose, has been dismissed too lightly. Suppose the glands which secrete this material should be out of operation for an hour; there would be sufficient departure from the normal condition to allow any prevailing invader, be it a recognized germ or a so-called filtrable virus, to pass the first line of defense. This same thought was expressed in a paper which I read before the Indiana Academy of Ophthalmology and Otolaryngology in 1934.1 It has been known for many years that nasal respiratory mucous membrane must have cilia actively moving a thin sheet of mucus along in order to be normally healthy and that one without the other is more or less helpless. For instance, in cases of atrophic rhinitis, in which the cilia are absent, the mucus remains stagnant and soon becomes infected. Conversely, when cilia are removed from their moist surroundings they soon cease to function.2The cilia are found abundantly in the nose and nasopharynx but not in the vestibule or oropharynx. Their wavelike action results in mucus being swept backward, toward the nasopharynx. This movement is not in the form of an unbroken wave but appears periodically in isolated groups of cells. The action of the cilia is such that the pos-Read before the