9. Overview of Hemostasis

  1. Alvin H. Schmaier MD and
  2. Hillard M. Lazarus MD, FACP
  1. Alvin H. Schmaier MD

Published Online: 22 SEP 2011

DOI: 10.1002/9781444345254.ch9

Concise Guide to Hematology

Concise Guide to Hematology

How to Cite

Schmaier, A. H. (2011) Overview of Hemostasis, in Concise Guide to Hematology (eds A. H. Schmaier and H. M. Lazarus), Wiley-Blackwell, Oxford, UK. doi: 10.1002/9781444345254.ch9

Editor Information

  1. Case Western Reserve University, University Hospitals Case Medical Center, Cleveland, OH, USA

Author Information

  1. Case Western Reserve University, University Hospitals Case Medical Center, Cleveland, OH, USA

Publication History

  1. Published Online: 22 SEP 2011
  2. Published Print: 4 NOV 2011

ISBN Information

Print ISBN: 9781405196666

Online ISBN: 9781444345254

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Keywords:

  • hemostasis;
  • thrombosis;
  • coagulation;
  • fibrinolysis;
  • anticoagulation;
  • prothrombinase;
  • tenase;
  • vitamin K-dependent blood coagulation factors;
  • contact activation of plasma;
  • plasma kallikrein/kinin system;
  • tissue factor

Summary

Disorders of hemostasis and thrombosis arise from the loss of the elegant balance of activation and inhibition among the protein and cells systems that prevent bleeding and regulate the extent of clot formation. Hemostasis which is the cessation of bleeding consists of both cellular and protein components. The surface of platelets and endothelial cells are the main locus where hemostasis occurs. The protein components consist of three systems: coagulation, fibrinolysis, and anticoagulant. When there is a bleeding risk, hemostasis is initiated by tissue factor and factor VIIa. Thrombosis or blood clot occlusion of vessels arises from both expression of tissue factor and factor VIIa or activation of factor XII upon contact with various anionic biologic surfaces. The goal of hemostasis is to generate thrombin in a kinetically fast manner to stop bleeding in a sufficient manner without vessel occlusion and downstream tissue ischemia. Two critically important coagulation protein assemblies, the tenase and prothrombinase complexes contribute to thrombin generation. Three major anticoagulant systems: protein C and S, antithrombin, and tissue factor pathway inhibitor limit the extent of thrombin formation. These reactions occur in the intravascular compartment and on or about cell surfaces.