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The PFA-100 (Platelet Function Assay — 100) is a system for analysing platelet function in which citrated whole blood is aspirated through a disposable cartridge containing an aperture within a membrane coated with either collagen and epinephrine or collagen and ADP. These agonists induce platelet adhesion, activation and aggregation, leading ...
Platelets are regulators of hemostasis and thrombosis. Platelets become active in the blood following vascular injury. Vascular injury causes platelets to stick to the cellular matrix that is exposed under the endothelium, form a platelet plug, and then form a thrombus. Platelets are essential in the formation of an occlusive thrombus and are ...
Exposure of blood to the subendothelial space initiates two processes: changes in platelets, and the exposure of subendothelial platelet tissue factor to coagulation factor VII, which ultimately leads to cross-linked fibrin formation. Platelets immediately form a plug at the site of injury; this is called primary hemostasis.
Tissue factor, also called platelet tissue factor or Coagulation factor III, [5] is a protein present in subendothelial tissue and leukocytes which plays a major role in coagulation and, in humans, is encoded by F3 gene. Its role in the blood clotting is the initiation of thrombin formation from the zymogen prothrombin.
Clot retraction is dependent on the release of multiple coagulation factors from platelets trapped in the fibrin mesh of the clot. Thus, failure to retract can be a sign of thrombocytopenia or a rare condition called thrombasthenia. Blood clot prevention can be of use before this condition develops.
Platelets collected by using apheresis at an American Red Cross donation center. Not all platelet transfusions use platelets collected by automated apheresis. The platelets can also be separated from donations of whole blood collected in a traditional blood donation, but there are several advantages to separating the platelets at the time of collection.
Thrombopoietin is a glycoprotein hormone produced by the liver and kidney which regulates the production of platelets. It stimulates the production and differentiation of megakaryocytes, the bone marrow cells that bud off large numbers of platelets. [5] Megakaryocytopoiesis is the cellular development process that leads to platelet production.
One primary function of thromboregulation is the control of primary hemostasis, which is the platelet aggregation process. Some thromboregulators enhance platelet aggregation and some others inhibit the process. Platelet aggregation plays a critical role in the genesis of a resulting thrombus. Adhesion should remain local, but platelet ...