| actinozoal | <zoology> Of or pertaining to the Actinozoa. Source: Websters Dictionary (01 Mar 1998) |
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| actinozoon | <zoology> One of the Actinozoa. Source: Websters Dictionary (01 Mar 1998) |
| actinula | <zoology> A kind of embryo of certain hydroids (Tubularia), having a stellate form. Origin: NL, fr. Gr, a ray. Source: Websters Dictionary (01 Mar 1998) |
| action | 1. A process or condition of acting or moving, as opposed to rest; the doing of something; exertion of power or force, as when one body acts on another; the effect of power exerted on one body by another; agency; activity; operation; as, the action of heat; a man of action. "One wise in council, one in action brave." (Pope) 2. An act; a thing done; a deed; an enterprise. (pl): Habitual deeds; hence, conduct; behavior; demeanor. "The Lord is a Good of knowledge, and by him actions are weighed." (1 Sam. Ii. 3) 3. The event or connected series of events, either real or imaginary, forming the subject of a play, poem, or other composition; the unfolding of the drama of events. 4. Movement; as, the horse has a spirited action. 5. <mechanics> Effective motion; also, mechanism; as, the breech action of a gun. 6. <physiology> Any one of the active processes going on in an organism; the performance of a function; as, the action of the heart, the muscles, or the gastric juice. 7. Gesticulation; the external deportment of the speaker, or the suiting of his attitude, voice, gestures, and countenance, to the subject, or to the feelings. 8. The attitude or position of the several parts of the body as expressive of the sentiment or passion depicted. 9. A suit or process, by which a demand is made of a right in a court of justice; in a broad sense, a judicial proceeding for the enforcement or protection of a right, the redress or prevention of a wrong, or the punishment of a public offense. A right of action; as, the law gives an action for every claim. 10. A share in the capital stock of a joint-stock company, or in the public funds; hence, in the plural, equivalent to stocks. "The Euripus of funds and actions." (Burke) 11. An engagement between troops in war, whether on land or water; a battle; a fight; as, a general action, a partial action. 12. The mechanical contrivance by means of which the impulse of the player's finger is transmitted to the strings of a pianoforte or to the valve of an organ pipe. Chose in action the product of the mass of a body by the space it runs through, and its velocity. Synonym: Action, act. In many cases action and act are synonymous; but some distinction is observable. Action involves the mode or process of acting, and is usually viewed as occupying some time in doing. Act has more reference to the effect, or the operation as complete. "To poke the fire is an act, to reconcile friends who have quarreled is a praiseworthy action." (C. J. Smith) Origin: OF. Action, L. Actio, fr. Agere to do. See Act. Source: Websters Dictionary (01 Mar 1998) |
| action current | An electrical current induced in muscle fibres when they are effectively stimulated; normally it is followed by contraction. (05 Mar 2000) |
| 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) |
| activase | <enzyme> A thrombolytic agent which works by activating the bodys own fibrinolytic system by activating the production of plasmin from plasminogen. Plasmin is an enzyme which degrades fibrin clots and fibrinogen, as well as several other protein clotting factors. (27 Sep 1997) |
| activate | 1. To render activity. 2. To become active. 3. <chemistry> To convert (a compound, as a provitamin or enzyme) into an active form or different compound, especially. Into one that has a particular biological action (for example ergosterol by irradiation to vitamin D2 for use in treating rickets). (13 Nov 1997) |
| activated acetaldehyde | The activated form of acetaldehyde that is formed during the decarboxylation of active pyruvate. Formed in alcohol fermentation and in carbohydrate metabolism. Synonym: a-hydroxyethylthiamin pyrophosphate. (05 Mar 2000) |
| activated amino acid | The product formed by the condensation of the acyl radical of an amino acid and adenosine 5'-monophosphate (originally in the form of adenosine 5'-triphosphate, with elimination of a pyrophosphoric group). Formed in the first step of protein biosynthesis. Synonym: activated amino acid. (05 Mar 2000) |
| activated atom | An atom possessing more than normal energy as a result of input of energy. See: excited state. Synonym: excited atom. (05 Mar 2000) |
| activated carboxylic acid | Derivative of a carboxyl group that is more susceptible to nucleophilic attack than a free carboxyl group; e.g., acid anhydrides, thioesters. (05 Mar 2000) |
| activated charcoal | <drug> A type of carbon produced through exposing a source material such as wood or bone to very high temperatures in the presence of steam, air or carbon monoxide. Activated carbon is very good at removing (adsorbing) contaminants and is used in water filters, to decolour solutions and is sometimes administered to poisoning victims. (15 Jan 1998) |
| activated choline | An intermediate in the formation of phosphatidylcholine (lecithin); formed by the action of cytidine 5'-triphosphate on phosphocholine, linking the choline phosphate group to the alpha-phosphate of the cytidine 5'-triphosphate to give a pyrophosphate. Synonym: activated choline, cytidine diphosphate choline. (05 Mar 2000) |