Blood 10 Flashcards
What is Thrombin produced by and what does it need to be in the presence of in the common pathway?
The inactive precursor prothrombin in the presence of prothrombinase complex
What does Thrombin activate in the common pathway?
Fibrinogen to fibrin
What is needed to convert Fibrin to its stable form?
Calcium and factor XIII
What two pathways can the active factor X pathway come from in vivo?
The Initiation of clotting pathway and the Amplification of plotting pathway
What are the steps in the Initiation pathway in vivo?
Tissues damage releases TF and in the presence of VII and calcium and phospholipid from the platelet surface activates factor X in the common pathway
What is different about the Initiation pathway in Vivo?
The combination produced activated both factor X in the common pathway and factor IX in the Amplification pathway
What is factor IX used?
In the amplification pathway in vivo
What is factor IX a component in and in what pathway?
Tenase in the amplification pathway
What can the combination produced in the initiation pathway activate?
Factor X and factor IX
What occurs when factor IX is activated by the initiation pathway?
It becomes part of Tenase in the amplification pathway
Which factor is not present in the Amplification pathway In Vivo and why?
Hageman’s factor XII, because it only causes problems clotting In Vitro
What starts off the Amplification pathway In Vivo?
Activation of factor IX
When can factor IX be produced in the amplification pathway In Vivo?
It can be produced by Initiation pathway or by factor XI in the presence of calcium
How is factor IX activated in the Amplification pathway in Vivo?
It is activated by factor XI in the presence of calcium
Once factor IX is activated in the Amplification pathway in vivo what occurs?
It joins the tenase complex and activates factor X in the common pathway
What activates factor XIII in the common pathway in vivo?
Thrombin
What can Thrombin activate in the Prothrombinase complex in vivo?
Factor V
What does Thrombin activating factor V in the prothrombinase complex in the common pathway do in vivo?
It causes the Prothrombinase complex to act more effectively
How can Thrombin affect the Tenase complex in the Amplification pathway in vivo?
It activates factor VIII
In which pathway is the Tenase complex found?
The amplification pathway in vivo
In which pathway is the Prothrombinase complex found?
In the common pathway in vivo
How does Thrombin activating factor VIII in vivo affect the amplification pathway?
It causes Tenase to act more effectively
What is the main role of Thrombin in vivo?
Convert fibrinogen to fibrin in vivo
What are the side roles of Thrombin in vivo?
- Activates factor XIII
- Activates factor V
- Activates factor VIII
- Activates factor XI
What does the activation of factor XIII do?
Convert unstable fibrin to stable fibrin
What does the activation of factor V do?
Increases the effectiveness of the Prothrombinase complex
What does activation of factor VIII do?
Increases the effectiveness of the Tenase complex
What does the activation of factor XI do?
Start off the amplification pathway
Why is Thrombin important in vivo?
It amplifies the response of blood clotting in many steps
Where does Thrombin amplify blood clotting in vivo?
- Converts fibrin to stable fibrin
- Activates factor V in prothrombinase in the common pathway
- Activates factor VIII in tenase in the amplification pathway
- Activates factor XI in the beginning of the amplification pathway
How does Thrombin affect Fibrin?
It converts fibrinogen to fibrin and converts fibrin to its stable form
How does Thrombin affect Thrombinase?
It activates factor V which is a component of prothrombinase
How does Thrombin affect Tenase?
It activates VIII which is a component of Tenase
How does Thrombin first affect the amplification pathway?
It activates factor XI
How do platelets change when they become activated?
They change their shape and release various substances
What protein can Thrombin also activate?
Protein C
What does the body use to ensure a clot only forms where it is needed?
Anticoagulants
What is Fibrinolysis?
The breakdown of a blood clot when we no longer need it
What are the Anticoagulants produced by the body?
- TFPI (Tissue Factor Pathway Inhibitor)
- Antithrombin 3
- Thrombomodulin
- Proteins C and S
How does TFPI act as an anticoagulant?
Inhibits active factor X and active factor VII
How does Antithrombin 3 act in anticoagulation?
Inhibits Thrombin
How does Thrombomodulin act in anticoagulation?
Changes thrombin activity
How does Protein C and S act in anticoagulation?
Inihbit active factor V and active factor VIII
How does Thrombin usually act in terms of Coagulation?
Thrombin is usually a procoagulant substance when not bound to thrombomodulin
What general effects does Thrombin have when bound to Thrombomodulin?
Anticoagulant activity
How does Thrombin exhibit anticoagulant activity?
Normal endothelial cells have Thrombomodulin (TM) which bind to Thrombin and modulates its activity. This activates protein C and causes the breakdown of clotting factors V and VIII inhibiting clotting
What occurs once the Thrombin and TM complex bind to protein C?
It causes the breakdown of factor V and VIII
