Blood Coagulation Flashcards
(87 cards)
What is thrombosis?
The formation of an unwanted clot within blood vessels or the heart.
What is a thrombus?
A clot that adheres to a vessel wall.
What is an embolus?
A clot that floats within the blood.
Why are thrombi and emboli dangerous?
They may occlude blood vessels.
What are the steps required for clot formation?
Platelet activation and aggregation, formation of thrombin, production of fibrin, when cross-linked, stabilizes the clot.
How do platelets respond to vascular trauma?
By adhesion to the injury site, release of intracellular granules, and aggregation of the platelets.
What initiates the coagulation cascade leading to fibrin formation?
Factors released from injured tissue and platelets.
How is thrombin formed?
From prothrombin (factor II) by factor Xa.
What does thrombin catalyze?
The conversion of fibrinogen to fibrin.
What stabilizes the clot?
Cross-linking of fibrin strands.
What do endothelial cells maintain to prevent pathological thrombosis?
A nonthrombogenic lining in blood vessels.
How does the maintenance of transmural negative electrical charge help in preventing thrombosis?
It prevents the adhesion of circulating platelets.
What activates the fibrinolytic pathway?
The release of plasminogen activators.
What degrades coagulation factors in the prevention of thrombosis?
The activation of protein C.
What do Heparin-like proteoglycans do in preventing thrombosis?
Inhibit coagulation.
What is the role of prostacyclin (PGI2) in thrombosis prevention?
It is a potent inhibitor of platelet aggregation.
Name three categories of drugs that affect blood coagulation.
Platelet inhibitors, anticoagulants, thrombolytics.
List the platelet inhibitors.
Aspirin, ticlopidine, clopidogrel, abciximab, dipyridamole, eptifibatide.
Name the anticoagulants.
Heparin,
Low molecular weight heparin: Enoxaparin, tinzaparin.
Bivalirudin, Lepirudin: Not available in Jordan.
dalteparin, rivaroxaban.
Warfarin.
Dabigatran.
Apixaban.
Name the thrombolytics.
Alteplase, streptokinase, urokinase.
Name the drugs used in the treatment of bleeding.
Aminocaproic acid, protamine sulfate, vitamin K, tranexamic acid, aprotinin.
When should antiplatelet therapy be initiated after an infarction or stroke to obtain significant benefit?
Within 2 hours.
Why are antiplatelet drugs administered as adjuncts to thrombolytic therapy along with anticoagulants like heparin?
To maintain perfusion and limit the size of myocardial infarction.
What do platelet aggregation inhibitors target to interfere with platelet aggregation signals?
Inhibit COX-1, block GPIIb/IIIa, or ADP, or increase cAMP.