reaction time

time (tīm) a measure of duration. Symbol t.

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activated partial thromboplastin time  (APTT) (aPTT) (PTT) the period required for clot formation in recalcified blood plasma after contact activation and the addition of platelet substitutes; used to address the intrinsic and common pathways of coagulation.

bleeding time  the duration of bleeding after controlled, standardized puncture of the earlobe or forearm; a relatively inconsistent measure of capillary and platelet function.

circulation time  the time required for blood to flow between two given points.

clotting time , coagulation time the time required for blood to clot in a glass tube.

inertia time  the time required to overcome the inertia of a muscle after reception of a stimulus from a nerve.

one-stage prothrombin time  prothrombin t.

prothrombin time  (PT) the rate at which prothrombin is converted to thrombin in citrated blood with added calcium; used to assess the extrinsic coagulation system of the blood.

reaction time  the time elapsing between the application of a stimulus and the resulting reaction.

stimulus-response time  reaction t.

thrombin time  (TT) the time required for plasma fibrinogen to form thrombin, measured as the time for clot formation after exogenous thrombin is added to citrated plasma.

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reaction time

n.

The interval between the presentation of a stimulus and the response to it.

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reaction time

Etymology: L, re, again, agere, to act; AS, tima

the interval between the application of a stimulus and the beginning of a response.

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reaction [re-ak´shun]

1. opposite action or counteraction; the response of a part to stimulation.

2. the phenomena caused by the action of chemical agents; a chemical process in which one substance is transformed into another substance or substances.

3. in psychology, the mental or emotional state that develops in any particular situation.

4. the specific cellular effect produced by foreign matter, as in testing for allergies. For specific reactions, see under the name, such as pirquet's reaction.

reaction of degeneration the reaction to electrical stimulation of muscles whose nerves have degenerated, consisting of loss of response to a faradic stimulation in a muscle, and to galvanic and faradic stimulation in the nerve.

reaction time the time elapsing between the application of a stimulus and the resulting reaction.

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reaction

1. opposite action or counteraction; the response of a part to stimulation.

2. the phenomena caused by the action of chemical agents; a chemical process in which one substance is transformed into another substance or substances.

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chain reaction

one which is self-propagating; a chemical process in which each time a free radical is destroyed a new one is formed.

coupled reaction

one in which the free energy released by one chemical reaction drives the other reaction.

dark reaction

photosynthetic reaction which fixes CO₂ into sugar and which occurs without exposure to light. Called also Calvin cycle.

reaction of degeneration

the reaction to electrical stimulation of muscles whose nerves have degenerated, consisting of loss of response to a faradic stimulation in a muscle, and to galvanic and faradic stimulation in the nerve.

delayed reaction

a reaction, such as an allergic reaction, occurring hours to days after exposure to an inducer.

false negative reaction

an erroneously negative reaction to a test.

false positive reaction

an erroneously positive reaction to a test.

first set reaction

see rejection.

immune reaction

1. immune response; see also immunity.

2. formation of a papule and areola without development of a vesicle following smallpox vaccination.

lengthening reaction

reflex elongation of extensor muscles that permits flexion of a limb.

leukemic reaction, leukemoid reaction

a peripheral blood picture resembling leukemia or indistinguishable from it on the basis of morphological appearance alone, characterized by immature leukocytes in the blood.

reaction pattern analysis

designed to replace archaic, non-specific descriptions of the reactions of the skin to noxious influences; recommended categories are (1) perivascular dermatitis, (2) interface dermatitis, (3) vasculitis, (4) nodular and diffuse dermatitis, (5) intradermal vesicular and pustular dermatitis, (6) subepidermal vesicular and pustular dermatitis, (7) perifolliculitis, folliculitis and furunculosis, (8) fibrosing dermatitis, (9) panniculitis, (10) atrophic dermatosis, (11) mixed reaction patterns.

second set reaction

see rejection.

reaction specificity

lack of production of by-products in enzymatic reactions with yields of products being nearly 100%.

Strauss reaction

development of suppurative peritonitis, localized to the scrotal sac, in the guinea pig after the intraperitoneal injection of material containing Burkholderia mallei.

stress reaction

1. alarm reaction.

2. gross stress reaction.

reaction time

the time elapsing between the application of a stimulus and the resulting reaction.

wheal-flare reaction

a cutaneous sensitivity rection to skin injury or administration of antigen, due to histamine production and marked by edematous elevation and erythematous flare.

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reaction time 

The time interval between the onset of a stimulus and the response of a subject. Visual stimulations with a flash of light give rise to reaction times varying between 130 and 180 ms. This figure diminishes significantly with age.