| tonicity | 1. A state of normal tension of the tissues by virtue of which the parts are kept in shape, alert, and ready to function in response to a suitable stimulus. In the case of muscle, it refers to a state of continuous activity or tension beyond that related to the physical properties; i.e., it is active resistance to stretch; in skeletal muscle it is dependent upon the efferent innervation. Synonym: tonus. 2. The osmotic pressure or tension of a solution, usually relative to that of blood. See: isotonicity. Origin: G. Tonos, tone (05 Mar 2000) |
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