| double layer | <physiology> The zone adjacent to a charged particle in which the potential falls effectively to zero. An excess or deficiency of electrons on the surface (charge, not to be confused with the transmembrane potential) leads to an equivalent excess of ions of the opposite charge in the surrounding fluid. For most cells, that have negative charges, there will be an excess of cations immediately adjacent to the plasma membrane and at physiological ionic strength the double layer is likely to be around 2-3 nm thick. (10 Oct 1997) |
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| anterior ligament of Helmholtz | See: anterior ligament of malleus. (05 Mar 2000) |
| Gibbs-Helmholtz equation | An equation expressing the relationship in a galvanic cell between the chemical energy transformed and the maximal electromotive force obtainable. (05 Mar 2000) |
| Helmholtz' axis ligament | <anatomy> A ligament forming the axis about which the malleus rotates; it consists of two portions extending from the anterior and the posterior border, respectively, of the tympanic notch to the malleus. Synonym: axis ligament of malleus. (05 Mar 2000) |
| Helmholtz energy | Energy equivalent to the internal energy minus the entropy contribution (TS). (05 Mar 2000) |
| Helmholtz-Gibbs theory | An equation expressing the relationship in a galvanic cell between the chemical energy transformed and the maximal electromotive force obtainable. (05 Mar 2000) |
| Helmholtz, Hermann von | <person> German physician, physicist, and physiologist, 1821-1894. See: Helmholtz' axis ligament, Helmholtz energy, Helmholtz theory of accommodation, Helmholtz theory of colour vision, Helmholtz theory of hearing, Helmholtz-Gibbs theory, Gibbs-Helmholtz equation, Young-Helmholtz theory of colour vision. (05 Mar 2000) |
| Helmholtz theory of accommodation | That the ciliary muscle relaxes for near vision and allows the anterior aspect of the lens to become more convex. (05 Mar 2000) |
| 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) |
| Helmholtz theory of hearing | That the basilar membrane of the cochlea acts as a resonating structure, recording low tones from its apical turns and high tones from its basal turns. Synonym: Helmholtz theory of hearing. (05 Mar 2000) |
| 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) |
| bufadienolides (two double bonds) | Bufatrienolides (three double bonds), etc; they have varying numbers of hydroxyl groups at positions 3, 5, 14, and 16, and these may be further substituted. For structure, see steroids. (05 Mar 2000) |
| bufenolides (one double bond) | (05 Mar 2000) |
| carbon-carbon double bond isomerases | <enzyme> Enzymes that catalyze the shifting of a carbon-carbon double bond from one position to another within the same molecule. Registry number: EC 5.3.3 (12 Dec 1998) |
| RNA, double-stranded | RNA consisting of two strands as opposed to the more prevalent single-stranded RNA. most of the double-stranded segments are formed from transcription of DNA by intramolecular base-pairing of inverted complementary sequences separated by a single-stranded loop. Some double-stranded segments of RNA are normal in all organisms. (12 Dec 1998) |