| telephone theory | A theory of pitch perception which states that the cochlea possesses no faculty of sound analysis, but that the frequency of the impulses transmitted over the auditory nerve fibres corresponds to the frequency of the sound vibrations, and is the sole basis for pitch discrimination; a theory no longer tenable. (05 Mar 2000) |
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| theory | In science, an explanation for some phenomenon which is based on observation, experimentation, and reasoning. In popular use, a theory is often assumed to imply mere speculation, but in science, something is not called a theory until it has been confirmed over the course of many independent experiments. Theories are more certain than hypotheses, but less certain than laws. (09 Oct 1997) |
| theory of electrolytic dissociation | The theory of electrolytic dissociation (1887) that became the basis of our modern understanding of electrolytes: in an electrically conductive solution (e.g., acid, base, or salt), free ions are present before electrolysis, and the proportion of molecules dissociated into ions can be calculated from measurements of electrical conductivity as well as of osmotic pressure. Synonym: Arrhenius law. (05 Mar 2000) |
| theory of medicine | The science, as distinguished from the art, or practice, of medicine. (05 Mar 2000) |
| thermodynamic theory of narcosis | That the interposition of narcotic molecules in nonaqueous cellular phase causes changes that interfere with facilitation of ionic exchange. (05 Mar 2000) |
| Ehrlich's theory | Ehrlich postulated that cells contained surface extensions or side chains (haptophores) that bind to the antigenic determinants of a toxin (toxophores); after a cell is stimulated, the haptophores are released into the circulation and become the antibodies. See: receptor. Synonym: Ehrlich's postulate. (05 Mar 2000) |
| emergency theory | A theory of the emotions, advanced by W.B. Cannon, that animal and human organisms respond to emergency situations by increased sympathetic nervous system activity including an increased catecholamine production with associated increases in blood pressure, heart and respiratory rates, and skeletal muscle blood flow. See: relaxation response. Synonym: Cannon's theory. (05 Mar 2000) |
| emigration theory | That neoplasms originate from various cell rests, i.e., embryonal cells thought to persist in various sites after the development of the foetal organs and tissues. Synonym: emigration theory. (05 Mar 2000) |
| endosymbiosis theory | The scientific theory that the organelles of eukaryotic cells arose when free-living procaryotic cells began living within other, larger free-living procaryotic cells and formed mutualistic symbiotic relationships with them. (09 Oct 1997) |
| enzyme inhibition theory of narcosis | That narcotics inhibit respiratory enzymes by suppression of the formation of high energy phosphate bonds within the cell. (05 Mar 2000) |
| James-Lange theory | That bodily changes, such as tachycardia or sweating, precede rather than follow the conscious perception of an emotion and by themselves evoke the emotional feeling. (05 Mar 2000) |
| two-sympathin theory | A theory, now obsolete, advanced by Cannon and Rosenblueth that two different types of substances (sympathin E and I) diffuse into circulation when adrenergic nerves are stimulated, although the mediator itself is the same. (05 Mar 2000) |
| jungian theory | A theoretical psychoanalytical system centreed around symbols of the unconscious with the unconscious material derived from two sources - the personal unconscious (repressed or forgotten experiences, thoughts and feelings) and the collective or objective unconscious (the universal inherited qualities which dispose the individual to behave as his ancestors). (12 Dec 1998) |
| Young-Helmholtz theory of colour vision | A theory that there are three colour-perceiving elements in the retina: red, green, and blue. Perception of other colours arises from the combined stimulation of these elements; deficiency or absence of any one of these elements results in inability to perceive that colour and a misperception of any other colour of which it forms a part. Synonym: Helmholtz theory of colour vision. (05 Mar 2000) |
| kern-plasma relation theory | A theory enunciated by Hertwig (1903) that a definite relation as to size normally exists in every cell between the mass of nuclear material and that of the protoplasm. Origin: Ger. Kern, kernel, nucleus (05 Mar 2000) |