(ak'-shun) [agere, to do or perform].
A doing; a working; especially the perform- ance of a function. A., After-, the brief persistence of negative variation of the elec- tric current in a tetanized muscle. A.s, Animal, voluntary movements. A. of Ar- rest. See Inhibition. A., Automatic. See A., Reflex. A., Capillary. See Attraction, Capillary. A., Diastaltic. See A., Reflex.
A., Electrocapillary, electric phenomena resulting from chemic reaction between dissimilar fluids connected by a capillary medium. A., Inhibitory. See Inhibition.
A., Katalytic, A., Contact. See Katalysis.
A., Local, the production of currents be- tween different parts of the same cell of a galvanic battery. A.s, Natural, the vegeta- tive functions. A.s, Pseudomotor, Heid- enhain's term for phenomena resulting from stimulation of the chorda tympani after section of the hypoglossal nerve; movements due to vascular or lymphatic engorgement.
A., Reflex, an involuntary movement of part of the body resulting from an impression carried by a sensory or afferent nerve to a center, and then sent back by an efferent nerve to the part, usually at or near the source of irritation. A., Safety-valve, the in- complete closure of the tricuspid valve, espe- cially in cases of resistance in the pulmonary circulation. A., Sexual, functioning of the generative apparatus. A.S, Vital, those es- sential to the continuance of vitality, as of the heart and lungs.
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