| surface-active agent | Agents that modify interfacial tension of water; usually substances that have one lipophilic and one hydrophilic group in the molecule; includes soaps, detergents, emulsifiers, dispersing and wetting agents, and several groups of antiseptics. (12 Dec 1998) |
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| surface active compound | <biochemistry> Usually, in biological systems, means a detergent like molecule that is amphipathic and that will bind to the plasma membrane or to a surface with which cells come in contact, altering its properties from hydrophobic to hydrophilic or vice versa. (18 Nov 1997) |
| surface anatomy | The study of the configuration of the surface of the body, especially in its relation to deeper parts. (05 Mar 2000) |
| surface coil | A detector coil applied directly to a body part for high resolution imaging; often a single loop of metal. (05 Mar 2000) |
| surface envelope model | <biology> A way of treating the hydrodynamics of a ciliary field by considering the whole surface of the ciliate to have an undulating surface. The undulations arise because of metachronism. (18 Nov 1997) |
| surface epithelium | A layer of celomic epithelial cells covering the gonadal ridges as they are formed on the medial border of the mesonephroi near the root of the mesentery, the mesothelial covering of the definitive ovary. (05 Mar 2000) |
| surface mucous cells of stomach | Cell's lining the gastric surface and foveolae; a glycoprotein product at the apical end of each cell is secreted and forms a mucous protective film. Synonym: theca cells of stomach. (05 Mar 2000) |
| surface plasmon resonance | <chemistry> Alteration in light reflectance as a result of binding of molecules to a surface from which total internal reflection is occuring. Used in the Biacore (Pharmacia Trademark) machine that detects the binding of ligand to surface immobilised receptor or antibody. (19 Jan 1998) |
| surface potential | <cell biology, physiology> The electrostatic potential due to surface charged groups and adsorbed ions at a surface. It is usually measured as the zeta potential at the Helmholtz slipping plane outside the surface. (19 Jan 1998) |
| surface tension | The expression of intermolecular attraction at the surface of a liquid, in contact with air or another gas, a solid, or another immiscible liquid, tending to pull the molecules of the liquid inward from the surface; dimensional formula: mt-2. (05 Mar 2000) |
| surface tension theory of narcosis | That substances which lower the surface tension of water pass more readily into the cell and cause narcosis by decreasing metabolism. (05 Mar 2000) |
| surface thalamic veins | One or more veins running a subependymal course in a coronal plane over the thalamus, terminating in the internal cerebral vein. Synonym: lateral direct veins, surface thalamic veins. (05 Mar 2000) |
| surface thermometer | A thermometer in the form of a disk or strip that indicates the temperature of the portion of the skin to which it is applied. (05 Mar 2000) |
| surface water | <ecology> Water present above the substrate or soil surface. (09 Oct 1997) |
| symphysial surface of pubis | symphysial surface of pubis |