Prothrombin (Factors 2, 7, 9, 10) Quiz

Hemostasis and Coagulation

• Vasoconstriction is triggered by thromboxane A2 and endothelin right after tissue injury.
• Hemophilia A is deficient in Factor VIII (Anti-hemophilic Factor).
• Tissue plasminogen activator (t-PA) enzymatically converts plasminogen into plasmin.
• Platelet adhesion is part of the primary hemostasis system.
• Factor V is NOT part of the fibrinogen group in the coagulation system.
• Fibrin split products are cleared by the fibrinolytic system.

Vitamin K and Clotting Factors

• Vitamin K is essential for the synthesis of clotting factors, and the main source is dietary.
• Defective Vitamin K absorption due to biliary obstruction or fat malabsorption can lead to decreased synthesis of factors 5 & 8 in diseases like cholestasis.

Regulation of Coagulation

• Antithrombin III inhibits the activation of factors 5 & 8, causing hypercoagulation.
• Endothelin mediates vasoconstriction by acting on smooth muscles of the basement membrane during hemostasis.
• Calcium plays a crucial role in forming calcium bridges important for clotting, requiring calcium as a cofactor.

Coagulation Mechanisms

• The primary mechanism of coagulation in vivo is the extrinsic pathway.
• Factor XII is activated upon exposure to a negatively charged surface like glass or kaolin, initiating the contact phase of coagulation.
• Tissue plasminogen activator plays a role in fibrinolysis, breaking down fibrin clots.

Fibrinolysis and Wound Healing

• The temporary fibrin clot is systematically and gradually dissolved during wound healing through the fibrinolytic pathway.
• Plasminogen activator inhibitor-1 (PAI-1) is the enzyme responsible for activating FX in the common pathway.
• Thrombomodulin plays a role in both coagulation and fibrinolysis concurrently to restore blood flow.