SNEEZING (sternutatio) — the inborn reflex act of the person and the highest animals providing removal from upper respiratory tracts of dust, slime and other irritating agents by the forced exhalation after a short deep breath.
Ch.'s act is coordinated by nervous cells of a reticular formation at the level of a myelencephalon (see). Afferent impulses from mekhano-and chemoceptors of a mucous membrane of an average nasal sink and a nasal partition come on fibers of a trellised nerve to a ganglion of a trifacial (the node died away-serov) and further to neurons of a respiratory center (see). The combined reduction of muscles of a nasopharynx and respiratory muscles is provided with a heterochronic flow of efferent vozbuzhdeniye on phrenic and to intercostal nerves, and also on the glossopalatine, wandering and hypoglossal nerves; often there is a reduction of face muscles due to inclusion of a facial nerve and motor fibers of a trifacial. After a deep breath the soft palate rises and closes a postnaris, at the same time there is a reduction of muscles of palatal handles, and also a pripodnimaniye and moving away of language of a kzada, before contact with a hard palate. Then reduction of intercostal muscles, a diaphragm and direct muscles of a stomach creates the increased intrathoracic and intra belly pressure that is promoted also by the reduction of muscles of a throat causing closing of a glottis. Then the glottis and an entrance to a nasal cavity open, there is a forced exhalation, at Krom air goes preferential through a nose, clearing his mucous membrane of the irritating agents. At the same time pressure of expired air can reach 100 mm of mercury. and more; speed of the coming-out air in a glottis reaches 50 — 120 m/s, and rate of volume flow of an air flow — 12 l/sec. The flow of air passing through nasal and oral cavities takes droplets of slime and saliva, to-rye in the sprayed look
Sometimes are carried on distance to 2 — 3 m Ch.'s acts can follow one after another. The speeded-up Ch. can be a symptom of acute respiratory and allergic diseases, and also arise at effect of the irritating toxic agents (a lewisite, Arminum, arsines, etc.). At Ch. distribution in the airborne way of causative agents of nek-ry infections is possible (flu, measles, chicken pox, etc.). Ch.'s disturbance can be observed at patients at bulbar paralysis (see).
Bibliography: Breslav I. S. and Glebovsky V. D. Regulation of breath, L., 1981; Physiology of breath, under the editorship of JI. JI. Chic, etc., D., 1973. Yu. A. Fadeyev.