33 Questions
What is the purpose of INR calculation?
To standardize PT results
Which of the following correlates with an ACT test?
More accurate than PTT if using a large dose of heparin
When should the ACT be measured after going on CPB?
3 minutes after going on CPB
What is the target INR for patients on warfarin?
Approximately 2-3 times more than the control
Which of the following is correct regarding a Platelet Count?
Number of platelets in the body
What is the primary role of platelets in hemostasis?
Forming a platelet plug
Which of the following best describes the initial response to blood vessel damage in hemostasis?
Vascular spasm
What is the main function of the fibrinolytic system in hemostasis?
Breaking down fibrin clots
Which of the following involves the activation of tissue factor (TF) in hemostasis?
Extrinsic pathway
What happens when there is no injury to blood vessels in terms of hemostasis?
Blood remains a liquid
In which of the following vessels are hemostatic mechanisms less effective in dealing with bleeding?
Arteries
What is the main role of the cell-based prothrombinase complex?
Convert prothrombin to thrombin
Which of the following is a key function of thrombin in the coagulation process?
Convert fibrinogen to fibrin
What is the role of the Factor VIIIa/IXa complex in the coagulation cascade?
Act as a cofactor for generation of large amounts of factor Xa
What is the primary function of TFPI in the clotting process?
Neutralizes tissue factor
Which of the following is a mechanism that limits the size of a clot in the coagulation process?
Activation of plasminogen
How does the Fibrinolytic System regulate clot breakdown?
By turning off fibrinolysis when no longer needed
What is the role of Factor XIII in the clotting cascade?
Stabilizes the fibrin meshwork
Why are activated platelets considered essential for the clotting cascade?
They display receptors that bind clotting factors
What is the function of thrombin in the clotting cascade?
Activates platelets
In the classical clotting cascade, which pathway is activated when coagulation is initiated outside of the blood vessels?
Extrinsic pathway
What occurs at the endpoint of both intrinsic and extrinsic pathways in the clotting cascade?
Thrombin production
Which enzyme is synthesized in the liver and is inactive until needed to digest fibrin?
Plasminogen
What is the role of tPA inhibitor (tPAI) in the fibrinolysis process?
Inhibits the conversion of plasminogen to plasmin
Which test assesses the intrinsic and final common pathway of coagulation?
Activated Partial Thromboplastin Time (aPTT)
What is the mechanism by which plasmin degrades fibrin?
It degrades fibrin into FDPs
Which factor must be reduced by more than 30% before a change in Prothrombin Time (PT) is observed?
Factors in the extrinsic pathway
What does Alpha-2 antiplasmin do in the context of fibrinolysis?
Inhibits the action of plasmin on fibrin
INR stands for International Normalization Ratio.
True
The normal value of INR is around 3.
False
Activated Clotting Time (ACT) is measured after heparin administration only.
False
Platelet Count measures the function of platelets.
False
ACT should be greater than 400 seconds before going on CPB.
True
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