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Coagulation Cascade

Series of events that are critical in the forming of fibrin, necessary to clot injuries.  

This is a highly informative video that visually walks the viewer through the process of clotting wounds and the cascade of events that allow this process to occur. In addition this video goes through the same process and explains what happens when there is an absence of Factors VIII or IX during the coagulation cascade. 

The Coagulation Cascade

 
  • When the average person experiences a cut, the body begins a series or cascade of processes to create a hemostatic(the stopping of a flow of blood) blockage.
  • The coagulation system is responsible for the cascade of events that eventually form the fibrin (an insoluble protein formed from fibrinogen; forms a fibrous mesh that impedes the flow of blood).
  • The events of the hemostatic system are classified into to two responses
  • The primary hemostatic response, which includes vasospams(sudden constriction of a blood vessel, reducing its diameter and flow rate) and the formation of a platelet plug (cell fragments that clump together at wound sites and release chemicals that cause blood to clot) (Hughes, Garlick, Bliss, and Connolly 158).
  • Platelets are the foundation of primary hemostasis and they adhere to exposed collagen (the main structural protein found in animal connective tissue). Platelets are also moderated by the von Willebrand factor. (vWF) (Lee). The von Willebrand disease is very similar to hemophilia, they both deal with a deficiency in a clotting factor leading to a difficulty in creating clots to stop bleeding. However the von Willebrand disease wasn't categorized as a type of hemophilia, because unlike hemophilia, von Willebrand disease deals with the platelets which affect the primary hemostatic response.
  • The primary hemostatic response creates a platelet aggregation and produces the exposure of negatively charged platelet membrane phospholipids. These negatively charge platelet membrane phospholipids provides a surface for the assembly of the procoagulant clotting factors, part of the secondary hemostatic process (Lee).
  • The secondary hemostatic response is the activation of the procoagulant system.
  • The procoagulant cascade (image on below), is the process by which the procoagulant system achieves it's objective of forming a fibrin clot. The coagulant cascade starts with the vascular injury and “cascades” down a series of chemical activations that initiate factor activity and result in a fibrin (cross-linked) clot (Lee).
  • The parts of the procoagulant cascade most relevant to hemophilia are factors XIII and IX.

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