Hemostasis Flashcards
What is the diference between the platelet system and the coagulation system?
Platelet system only forms a temporary platelet clot.
Coagulation system creates and insoluble clot with fibrin.
Thromboxane A2 and Serotonin from activated platelets causes what?
Causes vasoconstriction at the site of injury.
Thrombin from the coagulation system causes what?
Induces blood vessel endothelial cells to release endothelin which causes vasoconstriction.
Platelet tethering to the site of injury occurs by interlocking of which two materials?
GP1b on the paltelet to the von willebrand factor on the exposed subendothelial collagen.
What effect does platelet glycoprotein VI have?
Binds to collagen at injury site to induce adhesion of adjacent platelets through use of GPIIB-IIIa
Leads to release of platelet activators (ADP, Serotonin, and TXA2)
What does GPIIa/IIIb bind following platelet activation?
Binds fibrinogen tethering multiple platelets together.
APP from activated platelets activates what receptor?
Activates purinergic P2Y12 receptors.
Thrombin from the coagulation pathway activates what receptors?
Activates protease activated receptors (PARs)
Thromboxane A2 (TXA2) from activated platelets activates what receptor trype
TXA2
How is prothrombin made?
Consistently made in the liver by factor 10a interacting with factor 5a in the presense of phospholipids and calcium.
This is known as the prothrombin activator complex.
What forms the tenase complex?
Factor 8 (activated from thrombin) complexes with factor 9 to form the tenase complex.
What does the Tenase complex do?
The tenase complex greatly upregulates the formation of Factor 10.
What is the Tssue factor comlex?
Tissue factor with Factor 7 speeds up thrombin production massively.
Hematophilia is a deficiency of which clotting factor?
Factor 8 which shuts down the tenase complex.
What substance is used in the PT test?
PT uses thromboplastin which acts as tissue factor.
What effect does Thrombomodulin have?
Thrombomodulin activates protein C which can then activate protein S that degrades Factor Va and factor VIIIa
Where is thrombomodulin located?
Located on endothelial cells and is activated by thrombin creating a self regulating pathway.
What is factor V Leiden thrombophilia?
Mutations in factor V preventing it from being activated by APC leading to a hypercoaguable state.
What effect does antithrombin have
This is created by the liver and floats around the blood with a very slow mechanism for destroying free thrombin.
Whateffect does heparin have on clotting?
Heparin binds antithrobin and makes it extremely efficient at destroying free thrombin.
