Platelets What are platelets? Platelets - blood cells that non-nuclear discoid shape of 2-4 microns, which are formed in bone marrow from megakaryocytes. After maturation in the bone marrow, platelets come in bloodstream, which is circulating two thirds consist of bone marrow platelet, while the remaining third the number of platelets deposited in the spleen. The life span of platelets is 7-10 days after which the old platelets are absorbed by phagocytes. The normal platelet count in blood during the day is subject to fluctuations and may vary between 10% and in women during menstruation is reduced by 25-50%. Platelets perform angiotroficheskuyu and adhesively-aggregation functions, and participate in the processes of coagulation and fibrinolysis, provide a retraction of a blood clot. They are able to carry on its membrane, circulating other (aggregate) and adhered to the damaged vessel wall (the ability to adhere). Platelets have the ability to throw away their contents on stimulation of granules, which contain the clotting factors, enzyme peroxidase, serotonin, calcium ions - Ca2 *, adenosine diphosphate (ADP), von Willebrand factor, platelet-fibrinogen, platelet derived growth factor. Platelets. The norm of platelets in the blood of children and adults. For adults (men, women, including pregnant women) the rate of blood platelets is 180-320 x 109 / l, ie 180-320 thousand cells ml. In infants up to 10 days normal platelet count is within the 100-420 x 109 / l in children aged under...

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