ANFS332 Lecture Notes - Lecture 4: Flatworm, Thrombin, Coagulation
22 Sep 2019
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Document Summary
The initial phase of the process is vascular constriction. This limits the flow of blood to the area of injury. Next, platelets aggregate at the site of injury, forming a temporary, loose platelet plug. By attaching to the platelets, fibrinogen then stimulates further platelet clumping or aggregation. To insure stability of the initially loose platelet plug, a fibrin mesh (the clot) forms and entraps the plug. Fibrinogen is converted to fibrin through protease (thrombin) which is activated by the clotting cascade. Finally, the clot must be dissolved in order for the normal blood flow to resume tissue repair. The dissolution of the clot occurs through the action of plasmin. Thrombin and fibrinogen need to be activated. They are activated by a cascade of activated clotting factors. Each pathway leads to an activation of factor x. The activated form of one clotting factor catalyzes the activation of the next factor. Thrombin and fibrinogen have to be activated.
