IHL I - Intrinsic and Extrinsic Coagulation Pathways Flashcards
thrombosis
results in a blood clot
hemostasis
maintain blood in a fluid state
endothelium
vascular
very important in hemostasis
what do endothelial cells produce?
NO, PGI2, and ADP
nitric oxide
vasodilator and anti-platelet effects
prostacyclin
vasodilator in lungs
ADP
adenosine diphosphate favor attachment of platelet to ECM
Adp (adenosine diphosphatase) - degrades ADP and inhibits the platelet adhesion
Adp
adenosine diphosphate
degrades ADP - and inhibits platelet adhesion
anti-coagulants of the endothelial cells?
heparin sulphate, thrombomodulin, proten S, Tissue factor pathway inhibitor
heparin sulfate
expressed by endothelial cells
hooks onto AT III (antithrombin III) and activates it
ATIII
inactivates thrombin, Xa, and IXa
factor 5 and factor 9**
makes sure coagulation does not occur where it shouldn’t
Thrombomodulin
expressed by endothelial cells
binds to thrombin and converts it to anticoagulant
-by activating protein C
Protein S
produced by endothelial cells
cofactor for protein C
TFPI
tissue factor pathway inhibitor
expressed by endothelial cells
inhibits factor VIIa and Xa
tissue type plasminogen activator
t-PA
synthesized by endothelial cells
activates plasminogen to plasmin
plasmin
degrades fibrin to FDP (fibrin degradation product)
dissolves thrombi
primary hemostasis
localized platelet is formed at site of endothelial injury site
secondary hemostasis
initial platelet plug is enlarged and fibrin is added
-coagulation starts
antithrombosis
clot formation must cease when it is formed
fibrinolysis
last major steop in hemostatis
remove the clot and restore normal blood flow fibrinolysis
what happens when endothelium is damages?
vasoconstriction and vasospasm
-vessel constriction - less blood flow, less blood loss
endothelin
vasoconstrictor released by injured endothelium
vWF
synthesized by the endothelial cells when injured
attaches to the exposed ECM of the injured endothelium
allow the platelets to stick to the site of injury
where does the vWF stick to?
the ECM that is exposed during injury of the endothelial cells
GpIb
glycoprotein on platelets that is receptor for vWF on the ECM of the injured sit
what activates the platelet?
binding of the GpIb to vWF
causes the release of TX A2, delta granules, and alpha granule
what is in delta granules
SAC
serotonin - vasoconstrictor
ADP platelet activator and aggregator
calcium - activates coag factor
alpha granules
coagulating factors
fibrinogen
platelet derived growth factor
primary hemostasis involves what?
vasoconstriction, platelet adhesion, aggregation, and secretion
fibrinogen
binds platelets to one another via GpIIb/IIIa receptors
thrombocytopenia
low levels of platelets
filopodia
extensions from platelets that allows for aggregation
secondary hemostasis?
fibrin production
fibrinogen
soluble form
fibrin
insoluble form
secondary hemostatic plug
fibrin has been present and it polymerizes causing a “cemented” plug
to pathways to initiate coagulation?
intrinsic and extrinsic
intrinsic pathway
clotting initiated from something in the blood
**calcium
extrinsic pathway
clotting initiated by the tissues
**tissue factor
what is the factor where the intrinsic and extrinsic pathways converge?
X (10)
most important coagulation factor?
thrombin
thrombin
when activated, converts the soluble plasma protein fibrinogen into fibrin monomers that polymerize
what stabilizes the polymer of fibrin?
XIIIa
hageman factor
factor XII
initiates intrinsic pathway
> factor XI > factor IX
intrinsic pathway
starts with factor XII > factor XI > factor IX
tissue factor
initiates factor 7 (extrinsic pathway)
Christmas factor
factor IX
antihemophilic factor
factor VIII
stuart factor
factor X
what converts fibrinogen to fibrin?
thrombin
prothrombinase
requires Ca2+
converts prothrombin to thrombin
what is factor I?
fibrinogen
what allows for the stabilized fibrin polymer?
factor XIII
Ca2+
roles of thrombin?
converts fibrinogen to fibrin
activates leukocytes
induces platelet aggregation
plasminogen
circulating protein converted by tPA to plasmin
plasmin
enzymatic degradation of fibrin
t-PA converts circulating plasminogen to plasmin
t-PA
secreted by endothelium
converts plasminogen to plasmin
u-PA
secreted by kidney
also convert plasminogen to plasmin
two pathological problems of thrombus?
vascular obstruction or embolism
embolism
mobile clot
what breaks down the fibrin clot?
plasmin
what makes the fibrin from fibrinogen?
thrombin