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MLAB 1227- Coagulation Keri Brophy-Martinez

MLAB 1227- Coagulation Keri Brophy-Martinez. Overview of Hemostasis: Part One. Hemostasis. Heme= blood stasis= to halt Process of retaining blood within the vascular system Repairs injury to blood vessels Stops or prevents blood loss. Fibrinogen. Procoagulant Factors.

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MLAB 1227- Coagulation Keri Brophy-Martinez

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  1. MLAB 1227- CoagulationKeri Brophy-Martinez Overview of Hemostasis: Part One

  2. Hemostasis • Heme= blood • stasis= to halt • Process of retaining blood within the vascular system • Repairs injury to blood vessels • Stops or prevents blood loss

  3. Fibrinogen Procoagulant Factors RegulatoryFactors Fibrin Balance of Hemostasis *Balance of bleeding (hemorrhaging) and clotting (thrombosis) *Imbalance in one direction can lead to: bleeding : hypocoagulable state OR thrombosis: hypercoagulable state

  4. Hemostasis • Components • Vascular System • Controls rate of blood flow • Platelet System • Interaction of vasculature and platelets form a temporary plug • Coagulation System • Forms a stable insoluble plug (i.e) fibrin forming • Fibrinolytic System • Fibrin lysing • Coagulation Inhibition System • Natural inhibitors • Control fibrin formation and fibrin lysis

  5. Hemostasis Failure or deficiencies in any of the five systems involved with hemostasis can leads to varying degrees of uncontrolled hemorrhaging or clotting

  6. Hemostasis The hemostatic components remain inert in the presence of intact vascular tissue or endothelium Following injury, each component must function optimally.

  7. Hemostasis: OverviewConsists of three stages • Primary Hemostasis • Process of blood clotting in response to injury or desquamation of dying /damaged endothelial cells • Blood vessels (vasculature) and platelets are the main “players.” • Primary Hemostatic plug is formed • Platelet plug temporarily arrests bleeding. Insoluble fibrin strands deposit on the initial plug to reinforce and stabilize. The fibrin originates from soluble plasma proteins. • Secondary Hemostasis • Actions of the protein coagulation factors form fibrin in response to injury • Fibrin is stabilized by Factor XIII • At this time, blood has changed into a solid state • Fibrinolysis • Clot is removed following healing of wound

  8. Stages of Hemostasis http://tinyurl.com/8w8redf

  9. Vascular System • Components • Arteries/ Arterioles • Carry blood from the heart to capillaries • Thickest walls of the vasculature • Veins/Venules • Return blood from capillaries to the heart • Thinnest walls of vasculature • Capillaries • No vessel wall • Do not contribute to hemostasis

  10. Vascular System:Anatomy of the Blood Vessels • Structure • Endothelium • Single layer of endothelial cells, lining vessels • Coated by glycocalyx (protein and mucopolysaccarides) • Protects basement membrane • Negatively charged, repels circulating proteins and platelets • Secretes substances to keep the blood vessel in a nonreactive environment

  11. Vascular System: Anatomy of the Blood Vessels • Structure con’t • Subendothelium • Smooth muscle and connective tissue with collagen fibers • Basement membrane • Collagen material – stimulates platelets • Connective tissue • Elastic fibers- provide support around vessels

  12. Vascular System: Blood Vessels • Daily Function • Endothelium • Controls vessel permeability • Controls blood flow rate • Produces and releases substances that inhibit OR stimulate platelets, coagulation and fibrinolysis

  13. Hemostatic Trigger • Once vessel damage occurs, action begins! • Arteries and arterioles vasoconstrict • Smooth muscle cells contract to reduce blood flow • The endothelium becomes thrombogenic • Platelets and coagulation proteins are activated • Fibrinolysis initiated

  14. How Does the Endothelium Become Thrombogenic? • Actions • Von Willebrand’s Factor is made and released to assist the platelets in primary hemostasis • Produce tissue factor needed for secondary hemostasis • Collagen is exposed which secretes platelet activating factor which in turn activates platelets • Subendothelium promote the binding of leukocytes • Plaminogen activator inhibitor is released to inhibit fibrinolysis

  15. Resting “Normal”

  16. Vascular System: Function Following Injury • Initiate hemostasis: FIRST RESPONSE • Vasoconstriction of the arterioles • Minimizes blood flow to injured area • Prevents blood loss • Delivers platelets and plasma proteins to the vessel wall • Immediate • Short-lived

  17. Vasoconstriction • Mechanism • Neurogenic factors • Regulatory substances • Prolong vasoconstriction • Serotonin ( made by platelet activation & endothelium) • Thromboxane A2 ( made by platelet activation & endothelium) • Endothelin-1 (made by damaged endothelial cells)

  18. Roles of the Healthy Endothelium • Prostaglandin (PGI2)/ Prostacyclin • Vasodilates to increase blood flow to bring fresh supplies of clotting substances • Inhibits platelet aggregation • Causes redness at the injury site

  19. Additional Roles • Contraction of venules • Causes gaps between them which pushes fluids causing edema or swelling • Inflammatory response

  20. References McKenzie, Shirlyn B., and J. Lynne. Williams. "Chapter 29." Clinical Laboratory Hematology. Boston: Pearson, 2010. eMedTV. (2009, August 12). How Does Blood Clot.[Video file]. Retrieved from http://www.youtube.com/watch?v=--bZUeb83uU

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