| saturation | 1. The act of saturating, or the state of being saturating; complete penetration or impregnation. 2. <chemistry> The act, process, or result of saturating a substance, or of combining it to its fullest extent. 3. <optics> Freedom from mixture or dilution with white; purity; said of colours. The degree of saturation of a colour is its relative purity, or freedom from admixture with white. Origin: L. Saturatio: cf. F. Saturation. Source: Websters Dictionary (01 Mar 1998) |
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| saturation analysis | General term for an assay in which a binder competes for labelled versus unlabelled ligand; following separation of free and bound ligand, the ligand (the analyte assayed) is quantitated by relating bound and unbound ratios to known standards. See: enzyme-linked immunosorbent assay, radioreceptor assay, immunoassay, enzyme-multiplied immunoassay technique, radioimmunoassay. Synonym: displacement analysis, saturation analysis. (05 Mar 2000) |
| saturation index | An indication of the relative concentration of haemoglobin in the red blood cells, calculated as: grams of haemoglobin per 100 ml (expressed as percent of normal) ÷ haematocrit value (expressed as percent of normal) = saturation index The normal index for adults and infants is 0.97 to 1.02; in primary and secondary anaemia, the index is usually considerably less than 0.97. (05 Mar 2000) |
| saturation of receptors | Saturation, the state in which all receptors are effectively occupied all the time, can be said to occur in a simple binding equilibrium when the concentration of ligand is more than 5 times the Kd value, although strictly this will only be true at infinite ligand concentration. (18 Nov 1997) |
| secondary saturation | A technique of nitrous oxide anaesthesia consisting of an abrupt curtailment of the oxygen in the inhaled mixture to produce a deep plane of anaesthesia, following which oxygen is administered to correct hypoxia. (05 Mar 2000) |
| action current | An electrical current induced in muscle fibres when they are effectively stimulated; normally it is followed by contraction. (05 Mar 2000) |
| alternating current | Electrical current which alternates direction periodically. (For instance, household electric current is AC alternating at 60 oscillations/sec (60 Hertz) in the United States, and 50 Hertz in many other countries.) Acronym: AC (09 Oct 1997) |
| anodal current | A current produced in tissues under the anode when the circuit is closed. (05 Mar 2000) |
| ascending current | The direction of current flow in a nerve when the anode is placed peripheral to the cathode, in contrast to descending current; the convention used is that current flows from positive to negative. Synonym: centripetal current. (05 Mar 2000) |
| axial current | The central rapidly moving portion of the bloodstream in an artery. (05 Mar 2000) |
| bootstrap current | <radiobiology> Currents driven in toroidal devices by neo-classical diffusion. They may amount to a substantial fraction of the net current in a tokamak reactor, thus lengthening the pulse time or decreasing the power needed for current drive. (09 Oct 1997) |
| calcium current | Inflow of calcium ions through specific calcium channels. Critically important in release of transmitter substance from presynaptic terminals. (18 Nov 1997) |
| galvanic current | See: direct current, galvanism. (05 Mar 2000) |
| radio frequency current drive | <radiobiology> Plasma waves in the radio-frequency range can be used to push plasma particles in such a way that current forms in the plasma, this is a method of non-inductive current drive which would allow for steady-state fusion reactors to operate. (09 Oct 1997) |
| gating current | <physiology> Small currents in the membrane just prior to the increase in ionic permeability, due to the movement of charged particles within the membrane. So called because they open the gates for current flow through ion channels. (20 Mar 1998) |