| action current | An electrical current induced in muscle fibres when they are effectively stimulated; normally it is followed by contraction. (05 Mar 2000) |
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| action potential | <physiology> The sequential, electrochemical polarization and depolarisation that travels across the membrane of a nerve cell (neuron) in response to stimulation (touch, pain, cold, etc.) (09 Oct 1997) |
| action tremor | <neurology> A tremor which arises or which is intensified when a voluntary, coordinated movement is attempted. (18 Nov 1997) |
| back-action plugger | An instrument for condensing gold foil or amalgam in areas that cannot be reached directly. (05 Mar 2000) |
| ball valve action | The intermittent blockage of a tube or outlet of a cavity by some object or material that permits passage in one direction but not in the other. (05 Mar 2000) |
| calorigenic action | Increase of heat production of the body, as by the thyroid hormone. Synonym: thermogenic action. (05 Mar 2000) |
| capillary action | The phenomenon of a liquid such as water spontaneously creeping up thin tubes and fibres, this is caused by adhesive and cohesive forces and surface tension. (09 Oct 1997) |
| mass-action ratio | The ratio of the product of all of the product concentrations divided by the product of all of the reactant concentrations of a particular reaction; when the reaction has been completed (i.e., t = ∞), then this ratio is equal to the equilibrium constant. (05 Mar 2000) |
| mass action theory | That large areas of brain tissue function as a whole in learned or intelligent action. (05 Mar 2000) |
| mass action transmission | <epidemiology> Transmission of infection which occurs at a rate directly proportional to the number or density of both susceptibles and infecteds present. Some authors reserve the name mass action for transmission processes of the form b X Y/N , which we associate with STD-type transmission, and describe transmission rates of the form b X Y , as pseudo-mass action ; the two are equivalent if the population size is unchanging. (05 Dec 1998) |
| cumulative action | The condition in which repeated administration of a drug may produce effect's that are more pronounced than those produced by the first dose. Synonym: cumulative action. (05 Mar 2000) |
| salt action | Any physicochemical effect produced by hypertonic concentrations of osmotically active electrolytes. (05 Mar 2000) |
| prolonged action tablet | sustained action tablet |
| sparing action | The manner in which a nonessential nutritive component, by its presence in the diet, lowers the dietary requirement for an essential component; thus, nonessential l-cysteine spares essential l-methionine and nonessential l-tyrosine spares essential l-phenylalanine. Synonym: sparing phenomenon. (05 Mar 2000) |
| specific action | The action of a drug or a method of treatment which has a direct and especially curative effect upon a disease, e.g., the action of vitamin B12 in pernicious anaemia. (05 Mar 2000) |