Intrinsic and Extrinsic Coagulation Pathways (Choudhury) Flashcards
plasminogen
produced by liver. t-PA activates plasminogen to plasmin
Plasmin
degrades fibrin indo fibrin degradation product (FDP)
major players in extrinsic pathway for coagulation
tissue factor thromboplastin will activate factor VII so it can trigger activation of factor X in the common pathway
Major players in the intrinsic pathway for coagulation
factor XII(hageman) which activates XI to activate IX. IX works with VIIIa to activate X in common pathway
Describe common pathway of coagulation
When X is activated it will activate conversion of prothrombin to thrombin with the help of factor Vactivated and Ca2+
Thrombin then activates XIII and converts fibrinogen into fibrin
What causes propagation of coagulation pathways
Initiation that generates IIa will activate propagation
Anti-thrombin III
inactivates IIA, IXa and Xa
what does activated protein C do in coagulation
deactivates Va and VIIIa. Occurs when thrombin (IIa) combines with thrombomodulin
most important coagulation factor
thrombin
Prothrombin
prothrombin activator and Ca2+ convert prothrombin into thrombin
What type of feedback does thrombin give?
positive feedback to produce more
What does thrombin activate
converts fibrinogen to fibrin and activates fibrin-stabilizing factor XIII which in presence of Ca2+ stabilizes fibrin polymer through covalent bonding of fibrin monomers
what activates t-PA activity
fibrin (neg feedback)
What are the anti-coagulant properties?
heparin sulphate, thrombomodulin, Protein S and tissue factor Pathway inhibitor (TFP1)
Heparin Sulphate
activates Antithrombin III
Thrombomodulin
binds to thrombin and converts it from a procoagulatnt to anti by activating Protein C
TFPInhibitor
inhibits tissue factors VIIa and Xa
Normal sequence of events for hemostasis
Primary, secondary, anti thrombosis and fibrinolysis
Endothelin
acts on sm mm to cause vasoconstriction
what is contained in the dense granules
serotonin, ADP-platelet activator and aggregator, calcium
what is contained in the a granules
Coagulation factors, fibrinogen and PDGF
how long does it take for the primary plug to form
3-5 min
“fibrin polymerization”
secondary hemostasis when the cementing of platelets take place to form hemostatic plug.
5-10 min
How is the common pathway triggered
VIIa triggers common pathway via factor X in extrinsic
Intrinsically- VIIIa works with Ca to activate X
thromboplastin
factor III, a membrane-bound lipoprotein that is released by injured endothelial cells
General scheme and name of factors in extrinsic pathway
Thromboplasin III interacts with proconvertinVII and Ca2+ to activate the Stuart factor X
main role of factor X the stuart factor
to activate prothrombin activator.
General scheme and names of factors in intrinsic pathway
Exposed collagen activates Hageman factor XII which activates plasma thromboplastin anteceded PTA XI which with Ca2+ activate christmas factor IX which interacts with anti-hemophilic factor VIII. VIII plus Ca2+ activates stuart factorX
General scheme of common pathway with name of factor
Activated X interacts with Ca2+ and accelerin V to form prothrombin activator
What converts prothrombin into thrombin
prothrombinase (protrhombin activator) in presence of Ca2+
Urokinase-plasminogen activator
u-PA secreted by kidney circulates as inactie single-chain form (scu-PA) which must be converted by plasmin to for tcu-PA
