The clotting cascade occurs through two separate pathways that interact, the intrinsic and the extrinsic pathway. Extrinsic Pathway The extrinsic pathway is activated by external trauma that causes blood to escape from the vascular system. This pathway is quicker than the intrinsic pathway.
It involves factor VII. Intrinsic Pathway The intrinsic pathway is activated by trauma inside the vascular system, and is activated by platelets, exposed endothelium, chemicals, or collagen. This pathway is slower than the extrinsic pathway, but more important. Common Pathway Both pathways meet and finish the pathway of clot production in what is known as the common pathway. Instructor's Note: A diagram may be found in your text illustrating the clotting cascade.
The student does not need to be concerned about learning the details of these pathways. The student does need to realize that different factors are involved in each pathway.
If a patient does not clot normally, it is usually due to a platelet abnormality or deficiency, or by a defect or deficiency in one of the clotting factors. There are diagnostic tests which test for deficiencies in the intrinsic pathway, the extrinsic pathway, and platelet abnormalities. These tests allow the physician to narrow down and eventually discover the defect which is causing a patient to bleed excessively.
How coagulation happens What is a platelet? What is fibrin? Clotting factors Clotting and hemophilia Symptoms and complications Living with hemophilia Future hopes Takeaway Coagulation is the process of making blood clot.
How coagulation happens. Share on Pinterest Nosebleeds can occur easily when a person has hemophilia. What is a platelet? Clotting factors. Clotting and hemophilia. Symptoms and complications. Share on Pinterest When a person has hemophilia, they may bruise more easily and more severely than other people. Living with hemophilia. Share on Pinterest A person with hemophilia should not use aspirin or certain other drugs.
It is important to speak to a doctor before using any new medication. Future hopes. Scientists identify new cause of vascular injury in type 2 diabetes. Adolescent depression: Could school screening help? Related Coverage. What types of blood disorders are there? Medically reviewed by Elaine K. Luo, M. Internal bleeding: What you need to know.
How to tell if it is a bruise or a blood clot. Medically reviewed by Judith Marcin, M. How does blood work, and what problems can occur? What's to know about protein C deficiency?
Medically reviewed by Alana Biggers, M. Not all factors in the chain are activated and the clot cannot form properly. Know more. But wait, there's more! Explore more resources like our partner advocacy groups. Keep exploring. Stay connected Events are a great way to meet other people in the community. Find an event near you. Join us! The clotting process. World Federation of Hemophilia website. Updated January August 21, Role of the extrinsic pathway of blood coagulation in hemostasis and thrombosis.
Arteriosclerosis, Thrombosis, and Vascular Biology. Published June 7, Accessed August 26, What are rare clotting factor deficiencies? Updated May
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