Gourt > Health > Conditions and Diseases > Blood Disorders > Platelet
Platelets or thrombocytes are the blood cells that are involved in the cellular mechanisms of primary haemostasis that lead to the formation of blood clots. Low levels or dysfunction predisposes for bleeding, while high levels, although usually asymptomatic, may increase the risk of thrombosis.
Anatomy
Like red blood cells, platelets are anuclear (no cell nucleus) and discoid (disc shaped); they measure 1.5–3.0 μm in diameter. The body has a very limited reserve of platelets, so they can be rapidly depleted. They contain RNA, a canalicular system, and several different types of granules; lysosomes (containing acid hydrolases), dense bodies (containing ADP, ATP serotonin and calcium) and alpha granules (containing fibrinogen, factor V, vitronectin, thrombospondin and von Willebrand factor), the contents of which are released upon activation of the platelet. These granule contents play an important role in both hemostasis and in the inflammatory response.
Physiology
Production
Platelets are produced in the bone marrow; the progenitor cell for platelets is the megakaryocyte. This large, multinucleated cell sheds platelets into the circulation. Thrombopoietin (c-mpl ligand) is a hormone, mainly produced by the liver, that stimulates platelet production. It is bound to circulating platelets; if platelet levels are adequate, serum levels remain low. If the platelet count is decreased, more thrombopoeitin circulates freely and increases marrow production. More on [ Platelet ]
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Acquired Bleeding Disorders - An article by Thomas G. DeLoughery, Associate Professor of Medicine. Platelet transfusion therapy and dysfunctional platelets are discussed.
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Adult Chronic Immune Thrombocytopenic Purpura - A guide for patients. A description of this disease followed by an in depth look.
Idiopathic Thrombocytopenic Purpura - ITP: A look at what these words actually mean, what he causes are, who gets it, diagnosis, how it affects children and adults and pregnant women.
Meta Description: [ Information about idiopathic thrombocytopenic purpura from the American Academy of Family Physicians. ]
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Immune Thrombocytopenic Purpura - A look at the symptoms, diagnosis and treatment of this disorder. Where to look for more information.
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Immune Thrombocytopenic Purpura - What it is, symptoms of ITP, diagnosis, acute and chronic forms and treatment.
Meta Description: [ Idiopathic thrombocytopenic purpura (ITP) is a bleeding disorder in which the blood does not clot as it should. ]
Platelet Disorder Support Association - Information and support for those with immune thrombocytopenic purpura and other low platelet disorders
Meta Description: [ Comprehensive information and support for those concerned about ITP, Immune (Idiopathic) Thrombocytopenia Purpura. ]
Thrombocytopenia - Features information on this disorder and its causes, incidence and risk factors.
Thrombocytopenia During Pregnancy - An in depth look at gestational thrombocytopenia, idiopathic thrombocytopenic purpura, HELLP syndrome, toxemia of pregnancy, TTP and HUS, systemic lupus erythematosus and APA syndrome.
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Virtual Hospital: Bleeding Disorders - Differentiation of platelet versus coagulation defects, presentation, bleeding caused by qualitative platelet disorders and many more topics.
Meta Description: [ Virtual Hospital was a digital library of health information in pediatrics, paediatrics, and radiology for pediatric education and radiology education ]
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