Hemostasis coagulation Flashcards
What is Hemostasis?
Physiological mechanism of organism protection against unwanted bleeding.
Which steps participate in Hemostasis?
Blood vessels - vascular spasm
Thrombocyte aggregation
Coagulation cascade
What are crucial for in vitro work with blood samples and for diagnostics and treatment?
Anticoagulation treatment
What is hemostaseology?
Hemostaseology is science about the complex interactions between blood vessels, coagulation factors and blood cells.
What is a PT test?
Prothrombin time –> quick test
Which pathway does the quick test apply for?
The extrinsic coagulation pathway
How is quick test performed?
By adding thromboplastin and Ca2+ ions to the plasma.. It activates factor VII leading to direct sctivation of factor X followed by thrombin production and fibrin clot formation.
What is PT test mostly used for?
Monitoring coumarin therapy, which is an antagonist of Vitamin K, which is needed for factor VII, X and prothrombin carboxylation and function.
How must the blood be treated before a quick test?
Sample must be –> result stabilized by decalcification (citrate). Factor III and calcium ions is added. –> result in seconds
What is APTT?
Activated partial thromboplastin time.
What does APTT involve?
activation of a contact system which generates activation of factors XI, IXa and Xa. This iitiates thrombin production and fibrin clot formation.
What does APTT require?
an activating surface (kaolin or negative phospholipids) and Ca2+ ions.
What is APTT used for?
Monitoring Heparin therapy.
What is function of Heparin?
activator of antithrombin factor Xa, thrombin blocking. Can be used in vivo and in vitro.
Which anticoagulators works by decalcification?
sodiumcitrate, EDTA, oxalate
Only in vitro because of high amount of Ca2+ in body
What is function of warfarin?
inhibition of Vitamin K synthesis in liver
What activates the extrinsic coagulation factor?
Complex injury, blood must escape outside of the vessel
What activates the intrinsic factor?
Injury on mesothelium, exposed collagen from vessel wall.
Are the patients platelets important for the PT and APTT test?
No because both tests are done in platelet poor plasma.
What is the function of the thrombin time test ?
It involves adding thrombin to plasma and then test the fibrinogen clevage and fibrin clot formation.
What are D-dimers?
bi-products of fibrin clot formation.
What is DIC?
Disseminated intravascular coagulopathy
What is Hirudin?
A direct thrombin inhibitor produced by the leech hirudo medicinalis. Immdiate effect in vivo and in vitro.
What is definition of an anticoagulant?
a substance that prevents coagulation. Stops blood from clotting.
