Platelet

Platelet

Platelets, or thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are small, irregularly shaped clear cell fragments (i.e. cells that do not have a nucleus), 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is normally just 5 to 9 days. Platelets are a natural source of growth factors. They circulate in the blood of mammals and are involved in hemostasis, leading to the formation of blood clots.

If the number of platelets is too low, excessive bleeding can occur. However, if the number of platelets is too high, blood clots can form (thrombosis), which may obstruct blood vessels and result in such events as a stroke, myocardial infarction, pulmonary embolism or the blockage of blood vessels to other parts of the body, such as the extremities of the arms or legs. An abnormality or disease of the platelets is called a thrombocytopathy, which could be either a low number of platelets (thrombocytopenia), a decrease in function of platelets (thrombasthenia), or an increase in the number of platelets (thrombocytosis). There are disorders that reduce the number of platelets, such as heparin-induced thrombocytopenia (HIT) or thrombotic thrombocytopenic purpura (TTP) that typically cause thromboses, or clots, instead of bleeding.

Platelets release a multitude of growth factors including platelet-derived growth factor (PDGF), a potent chemotactic agent, and TGF beta, which stimulates the deposition of extracellular matrix. Both of these growth factors have been shown to play a significant role in the repair and regeneration of connective tissues. Other healing-associated growth factors produced by platelets include basic fibroblast growth factor, insulin-like growth factor 1, platelet-derived epidermal growth factor, and vascular endothelial growth factor. Local application of these factors in increased concentrations through Platelet-rich plasma (PRP) has been used as an adjunct to wound healing for several decades.

Read more about PlateletKinetics, Thrombus Formation, Other Functions, Discovery, In Transfusion Medicine, Other Species

Other articles related to "platelet, platelets":

Actinin, Alpha 1
... adherens • focal adhesion • Z disc • cortical actin cytoskeleton • platelet alpha granule lumen • pseudopodium • cell projection • extracellular ...
Cerastocytin - Function Overview
... leading to clot formation induce in platelet aggregation, they do so in various ways ... Willebrand factor (vWF) by inducing it to bind to platelet glycoprotein Ib (GPIb) thereby providing the surface for initial platelet aggregation ... Like thrombin, these proteases are capable of inducing platelet aggregation, and some even fibrin clot formation, at nanomolar concentrations ...
Platelet Adhesiveness
... Platelet adhesiveness refers to the processes or factors which lead to the adhesion of platelets to other structures ... It can be contrasted with platelet aggregation, which refers to the processes or factors which lead to the adhesion of platelets to other platelets ...
Cerastocytin - Inhibition
... Just as with thrombin, cerastocytin-activated platelet aggregation is inhibited by chlorpromazine, theophylline and mepacrine ... even though both have been observed to inhibit thrombin-facilitated platelet clot formation ... that cerastocytin has distinct sites for platelet and fibrinopeptide binding because the two functions could be inhibited independently of each other ...
Autotransfusion - Platelet Sequestration and Autologous Platelet Gel
... to provide separation of blood into three groups red cells, platelet poor plasma, and platelet rich plasma ... The red cells and platelet poor plasma can be given back to the patient through intravenous transfusion during or after surgery ... The platelet rich plasma can be mixed with calcium and thrombin to create a product known as autologous platelet gel ...