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blood clot·ting(blŭd kloting)
Synonym(s): blood coagulation.
blood clottingThe cascaded sequence of changes which occur when blood comes in contact with damaged tissue and which culminates in the production of a solid seal in the damaged vessel. At least 13 factors are consecutively involved in a process that culminates in the conversion of the protein fibrinogen to the fibrin that forms the main constituent of the clot. This last stage is catalyzed by the enzyme thrombin. The smooth endothelial lining of the blood vessels normally prevents clotting within the circulation, but damage to this lining may allow THROMBOSIS to occur.
blood clottinga condition where elements in the BLOOD PLASMA change consistency from a liquid to a gel-like structure, causing a ‘clot’ to form at the site of damage. The process of clotting is complex, but can be summarized as follows:
- damage to the blood circulatory system causes both BLOOD PLATELETS and the BLOOD VESSELS to secrete thromboplastin (see HAEMOPHILIA).
- thromboplastin, in the presence of calcium ions, causes prothrombin (a globulin type of plasma protein produced in the liver when vitamin K is present) to change to thrombin (see ANTICOAGULANT).
- thrombin acts as an ENZYME, causing FIBRINOGEN (another type of plasma protein) to be changed to fibrin which, when it contracts, forms a mesh of fibres in which blood cells become trapped. The final result of clotting is a hard lump which can plug the damaged area (if not too large) thus preventing further loss of blood and entry of microorganisms from outside.
blood coagulationthe process of clotting, which is one of the body's natural means of stopping bleeding (haemostasis), activated by damage to the vessel lining. Results from a complex cascade reaction, dependent on the presence of ionized calcium and involving many 'clotting factors', some always present in the blood and some released from damaged tissue and platelets. The endproduct is a mesh of fibrin in which blood cells are trapped to form a solid mass. See also anticoagulant.
Patient discussion about blood clotting
Q. What causes blood clots? My father had a heart attack which was caused by a blood clot. Am I at risk for developing blood clots too? How do I prevent it from happening?
Q. How can I prevent blood clots? I am 45 years old and am supposed to go on a business trip overseas. The flight itself is 12 hours long and then I have to continue traveling by bus. Could this cause me to have blood clots? If so, how can I prevent it?
Q. very dark blood clots @ first sight of period? At first sight of period, instead of normal rosy spotting it's brownish spotting followed by small clots.
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