platelet


platelet
/playt"lit/, n. Cell Biol.
a small platelike body, esp. a blood platelet.
[1890-95; PLATE1 + -LET]

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Small, colourless, irregular blood cell crucial in coagulation.

Produced in bone marrow and stored in the spleen, platelets accumulate to block a cut in a blood vessel and provide a surface for fibrin strands to adhere to, contract to pull the strands together, and take part in the conversion sequence of coagulation factors. They also store and transport several chemicals.

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also called  thrombocyte 
 colourless, nonnucleated blood component that is important in the formation of blood clots ( coagulation). Platelets are found only in the blood of mammals.

      Platelets are formed when cytoplasmic fragments of megakaryocytes, which are very large cells in the bone marrow, pinch off into the circulation as they age. They are stored in the spleen. Some evidence suggests platelets may also be produced or stored in the lungs, where megakaryocytes are frequently found.

      Platelets play an important role in the formation of a blood clot (coagulation) by aggregating to block a cut blood vessel and provide a surface on which strands of fibrin form an organized clot, by contracting to pull the fibrin strands together to make the clot firm and permanent, and, perhaps most important, by providing or mediating a series of clotting factors necessary to the formation of the clot. Platelets also store and transport several chemicals, including serotonin, epinephrine (epinephrine and norepinephrine), histamine, and thromboxane; upon activation these molecules are released and initiate local blood vessel constriction, which facilitates clot formation.

      At birth the number of platelets is low, but by three months of age the adult level is reached. The number of platelets rises following trauma or asphyxiation, at high altitudes, after exercise, and in cold temperatures; the number may be temporarily lowered by menstruation in women. Certain chemicals may prolong the life of platelets; smoking is believed to shorten their life spans.

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Universalium. 2010.

Look at other dictionaries:

  • platelet — platelet. См. тромбоцит. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • platelet — (n.) 1895, formed in English from PLATE (Cf. plate) + dim. suffix let …   Etymology dictionary

  • platelet — ► NOUN Physiology ▪ a small colourless disc shaped cell fragment without a nucleus, found in large numbers in blood and involved in clotting …   English terms dictionary

  • platelet — [plāt′lit] n. [ PLATE + LET] 1. any of certain round or oval, nonnucleated disks, smaller than a red blood cell and containing no hemoglobin, found in the blood of mammals and associated with the process of blood clotting 2. THROMBOCYTE (sense 1) …   English World dictionary

  • Platelet — Platelets, or thrombocytes, are small cytoplasmic bodies derived from cells. They circulate in the blood of mammals and are involved in hemostasis leading to the formation of blood clots. Like red blood cells, platelets have no nucleus. If the… …   Wikipedia

  • platelet — Anucleate discoid cell (3 m m diameter) found in large numbers in blood; important for blood coagulation and for haemostasis. Platelet a granules contain lysosomal enzymes; dense granules contain ADP (a potent platelet aggregating factor), and… …   Dictionary of molecular biology

  • platelet — UK [ˈpleɪtlət] / US noun [countable] Word forms platelet : singular platelet plural platelets biology a small piece of a cell in your blood that helps it to clot (= form a thick mass) …   English dictionary

  • platelet — noun Date: 1895 a minute flattened body (as of ice or a mineral); especially a minute colorless disklike body of mammalian blood that assists in blood clotting by adhering to other platelets and to damaged epithelium called also blood platelet,… …   New Collegiate Dictionary

  • platelet — noun A small colorless disk shaped particle found in the blood of mammals, which plays an important role in the formation of blood clots. Syn: blood platelet, thrombocyte …   Wiktionary

  • Platelet — An irregular, disc shaped element in the blood that assists in blood clotting. During normal blood clotting, the platelets clump together (aggregate). Although platelets are often classed as blood cells, they are actually fragments of large bone… …   Medical dictionary


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