Coagulation

Physiology

Hemostasis



Topic Completed: 1 June 2012

Minor changes: 22 September 2020

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed Search: Hemostasis [title]

Jeremy C. Parsons, M.D.
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Cite this page: Parsons JC. Hemostasis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/coagulationnormalhemostasis.html. Accessed October 20th, 2021.
Definition / general
  • Involves formation of blood clots to stop bleeding from damaged vessels, and activation of natural anticoagulation and fibrinolytic systems to limit clot formation to sites of injury
  • Bleeding disorders are due to defects in clot formation or overactive fibrinolytic systems
  • Hypercoagulability disorders are due to defects in anticoagulant system or underactive fibrinolytic systems
  • Primary hemostasis: initial step of forming platelet plug to stop bleeding from damaged vessel
  • Secondary hemostasis: platelet plug is reinforced by fibrin clot
    • Then fibrin clot is stabilized by activated factor XIII, which cross-links fibrin strands
  • Tertiary hemostasis: as fibrin clot is formed, plasmin is generated to break down the clot
  • Fibrin clot may occur via intrinsic or extrinsic pathway or both; in vivo it occurs via a hybrid model
Diagrams / tables

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Coagulation

Intrinsic, common, and extrinsic pathways

In vivo coagulation cascade

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