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see blood clottingblood clotting,
process by which the blood coagulates to form solid masses, or clots. In minor injuries, small oval bodies called platelets, or thrombocytes, tend to collect and form plugs in blood vessel openings.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(Factor III), an important coagulation factor in the blood-clotting system; it helps convert prothrombin into thrombin. Thromboplastin is localized in the membranes of formed elements of the blood and in the cells of various organs. A large amount of thromboplastin enters the blood upon injury to tissues. Brain and lung tissues have especially high thrombo-plastic activity, and lung thromboplastin also takes part in the metabolism of the vasoactive polypeptides angiotensin and bradykinin.

Chemically, thromboplastin is a protein-lipid complex. The basis of its activity is its lipid constituent, which contains serine, eth-anolamine, and choline phosphatides. Blood coagulation factors are adsorbed on the phospholipid micelle, creating favorable conditions for the enzymatic reactions involved in blood clotting.

The term “thromboplastin” is sometimes used to designate an active complex that includes, in addition to thromboplastin, a number of protein factors and Ca2+ ions. Such active thromboplastin, which directly converts prothrombin into thrombin, is also called thrombokinase or prothrombinase. Thromboplastin is used in clinical practice to determine the prothrombin level, an indicator of the condition of the blood-clotting system.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


Any of a group of lipid and protein complexes in blood that accelerate the conversion of prothrombin to thrombin. Also known as factor III; plasma thromboplastin component (PTC).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The findings of this study show significant increases in the prothrombin time and activated partial thromboplastin time of hypertensive patients when compared to those of the normotensives (control).
The program presents all data up to the time point when the next partial thromboplastin time (PTT) was actually determined.
Activated partial thromboplastin time was measured using PTT STA reagent and anti-Xa activity was measured using Rotachrom reagent (detection limit 0.1 IU/mL, intra-assay coefficient of variation across the measured range <5%) on the STA-R analyzer (reagents and analyzer from Diagnostica Stago, Parsippany, New Jersey).
A study of prothrombin time and activated partial thromboplastin time in liver cirrhosis.
Patients with reactive thrombocytosis also had a higher fibrinogen concentration (7.2 vs 5.8 g/1, P=0.003), a lower activated partial thromboplastin time (32 vs 35 seconds, P=0.012) and an increased incidence of infection requiring antibiotics (50 vs 27%, P=0.025) compared to patients without thrombocytosis.
Chapter 139 makes no mention of the prolongation of the partial thromboplastin time secondary to the lupus anticoagulant.
Dose-dependent shortening of activated partial thromboplastin time and prothrombin time, and an increase in peak thrombin, determined with a thrombin generation assay, was also observed.
"Resistance" to LA interference is primarily due to the higher concentration of phospholipids in the PT reagents compared with activated partial thromboplastin time reagents.
Besides, late second trimester and third trimester of pregnancy was found in 27(60%), unstable condition 10(22.22%), disturbed liver function test 24(53.3%) and raised serum glutamic pyruvic transaminase level greater than 101u/l 27(60%), deranged coagulation profile such as raised prothrombin time 25(55.5%), and activated partial thromboplastin time 18(40%)cases.
Monitoring for DTIs consisted primarily of activated partial thromboplastin time (89.9%; n = 187) and prothrombin time (82.2%; n = 171).
One similar done by Nihon Sanka et al; showed that in the third trimester, shortening of prothrombin time and activated partial thromboplastin time t11!.