Factor X: Diferenzas entre revisións
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== Factor Xa ==
[[Ficheiro:Coagulation in vivo-2.png|miniatura|350px|Vías da coagulación do sangue in vivo mostrando o papel central da trombina.]]
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O factor Xa é a forma activada do [[factor de coagulación]] [[tromboquinase]], coñecido polo epónimo de factor de Stuart-Prower. O factor X é un encima [[serina endopeptidase]], que desempeña un papel clave en varias enfermidades co [[sistema de coagulación]]. Factor X is [[Biosynthesis|synthesized]] in the [[liver]]. The most commonly used [[anticoagulants]] in clinical practice, [[warfarin]] and the [[heparin]] series of anticoagulants and [[fondaparinux]], act to inhibit the action of Factor Xa in various degrees.▼
▲O factor Xa é a forma activada do [[factor de coagulación]]
Os modelos tradicionais de coagulación desenvolvidos na década de 1960 concibían dúas fervenzas de reaccións, a vía extrínseca do [[factor tisular|factor tisular (TF)]] e a vía intrínseca. Estas vías converxían nun punto común a formación do complexo factor Xa/Va, que xuntoco [[calcio]] e unidos a unha superficie con [[fosfolípido]]s xeraban [[trombina|trombina (factor IIa)]] a partir da [[protrombina|protrombina (factor II)]].
A new model, the cell-based model of anticoagulation appears to explain more fully the steps in coagulation. This model has three stages: 1) initiation of coagulation on TF-bearing cells, 2) amplification of the procoagulant signal by thrombin generated on the TF-bearing cell and 3) propagation of thrombin generation on the [[platelet]] surface. Factor Xa plays a key role in all three of these stages.<ref name="HOCNA">{{cite journal | vauthors = Hoffman M, Monroe DM | title = Coagulation 2006: a modern view of hemostasis | journal = Hematology/Oncology Clinics of North America | volume = 21 | issue = 1 | pages = 1–11 | date = February 2007 | pmid = 17258114 | doi = 10.1016/j.hoc.2006.11.004 }}</ref>▼
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In stage 1, [[Factor VII]] binds to the [[transmembrane protein]] TF on the surface of cells and is converted to Factor VIIa. The result is a Factor VIIa/TF complex which catalyzes the activation of Factor X and [[Factor IX]]. Factor Xa formed on the surface of the TF-bearing cell interacts with [[Factor V]]a to form the [[prothrombinase| prothrombinase complex]] which generates small amounts of thrombin on the surface of TF-bearing cells.
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