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53 Cards in this Set
- Front
- Back
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what does normal homeostasis depend on?
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interactions in the vessel wall, platelets, soluble coagulation components
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how do vessel walls affect homeostasis?
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endothelial cells serve a 'barrier' function which prevents hemorrhage, and prevents contact of collagen with plasma and platelets (collagen activates platelets and factor XII)
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how do endothelial cells participate in blood coagulation?
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endothelial cells produce anticoagulatory factors and procoagulatory factors
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what are the anticoagulatory factors from endothelial cells?
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prostaglandin I2 (PGI2, prostacyclin), plasminogen activators, antithrombin III, heparin sulfate, alpha-2 macroglobulin
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name anticoagulatory factors from endothelial cells which are inhibitors of platelet aggregation?
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PGI2 (prostacyclin), nitric oxide, ADPase, plasminogen activators
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PGI2 (prostacyclin), nitric oxide, ADPase, plasminogen activators are examples of what?
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anticoagulatory factors from endothelial cells which are inhibitors of platelet aggregation
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what are prostaglandin I2 (PGI2, prostacyclin), plasminogen activators, antithrombin III, heparin sulfate, alpha-2 macroglobulin?
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anticoagulatory factors from endothelial cells
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what is prostaglandin I2 (PGI2, prostacyclin)?
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a potent inhibitor of platelet aggregation
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name anticoagulatory factors from endothelial cells that participate in anticoagulant binding and inhibition of thrombin?
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antithrombin III, heparin sulfate, thrombomodulin, alpha-2 macroglobulin
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antithrombin III, heparin sulfate, thrombomodulin, alpha-2 macroglobulin are examples of what?
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anticoagulatory factors from endothelial cells that participate in anticoagulant binding and inhibition of thrombin
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what does heparin sulfate do?
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inhibits activation of clotting factors
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what is alpha-2 macroglobulin?
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an antiprotease that inhibits activation of clotting factors
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what does thrombomodulin do?
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activation of protein C/S
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what is antithrombin III accelerated by?
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heparin-like molecules
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what do plasminogen activators (like t-PA) do?
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fibrinolysis
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what are the procoagulatory factors produced by endothelial cells?
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factor VIII related antigen (FVIIIR:Ag, von Willebrand factor, vWF), tissue factors, other
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what is factor VIII related antigen?
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required for platelet attachment to subendothelial components
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what tissue factors are procoagulatory?
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tissue thromboplastin
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what procoagulatory factors from endothelial cells stimulate platelet aggregation and adhesion?
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vWF, PAF, thromboxane A2
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what are the procoagulation factors from endothelial cells?
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tissue factor, IXa, Xa, V
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what procoagulatory factor from endothelial cells inhibit fibrinolysis?
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t-PA inhibitor
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what does t-PA inhibitor do?
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it's a procoagulatory factor from endothelial cells that inhibis fibrinolysis
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how do endothelial cells participate in blood coagulation?
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platelet activation: adhesion, aggregation and degranulation, consolidation
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what occurs during adhesion to subendothelial collagen during platelet activation?
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expression of surface receptors, cross-linkage of platelets with fibrinogen
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what occurs during aggregation and degranulation during platelet activation?
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degranulation of alpha granules, degranulation of electron-dense bodies, phospholipid complexes
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what surface receptors are expressed (and what does it bind to) by subendothelial cells during adhesion?
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GpIIb-IIIa on surface of platelets binds to fibrinogen and cross-links and vWF binds to receptors on platelet membranes via GpIb and collagen to bind molecular bridge between platelets/exposed collagen
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what is released during degranulation of alpha granules during platelet activation?
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releases fibrinogen, fibronectin, Beta-thrombospondin, factors V/VIII, PDGF, PF4, vWF
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what is released during degranulation of electron-dense bodies during platelet activation?
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releases ADP, Ca++, histamine, epinephrine, serotonin
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what occurs with the phospholipid complex during degranulation in platelet activation?
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the phospholipid complex on platelet surface becomes exposed as the stie for Ca++ and coagulatory factors to bind/activate intrinsic clotting system
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what happens during consolidation during platelet activation?
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activated platelets release Beta-thrombospondin, fibrinogen, and vWF, coagulation system yields fibrin which binds to platelet surfaces, consolidated platelets and fibrin form the definitive hemostatic plug
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what does ADP & TxA2 form in consolidation during platelet activation?
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temporary/primary hemostatic plug
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what occurs when thrombin binds to platelet thrombin receptor in consolidation during platelet activation?
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causes fibrinogen to become fibrin
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what occurs when a platelet aggregation undergoes contraction during platelet activation?
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results in a fused mass that undergos viscous metamorphasis to form the definitive/secondary hemostatic plug
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what does the definitive hemostatic plug consist of?
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consolidated platelets and fibrin
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what occurs immediately after a vascular injury?
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a transient vasoconstriction (reflex)
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what happens after a vascular injury?
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subepithelial collagen is exposed (platelets adhere via vWF), platelets undergo shape change and granule release of ADP and TXA2 to recruit more platelets that aggregate to form primary hemostatic plug
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what occurs after the formation of the primary hemostatic plug?
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tissue factor and platelet phospholipids activate local coagulation cascade, then activated thrombin cleaves fibriongen to fibrin to 'cement' platelets into definitive secondary hemostatic plug
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what does the definitive secondary hemostatic plug consist of?
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fibrinogen cleaved by activated thrombin to fibrin to 'cement' platelets
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what occurs after the formation of the definitive secondary hemostatic plug forms?
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antithrombotic factors are released that limit the hemostatic process to site of injury
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what are antithrombotic factors?
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tissue plasminogen activator (tPA) and thrombomodulin
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what does tissue plasminogen activator (tPA) do?
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fibrinolysis
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what does thrombomodulin do?
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limit hemostatic process to site of injury
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what type of system is the coagulation system?
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a cascade
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what does the coagulation system generate?
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fibrin which polymerizes on platelet surfaces cross-linked by factor XIII
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what are the pathways of the coagulation system and how do they interact?
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the intrinsic pathway and the extrinsic pathway which converge at Factor X and generate thrombin from prothrombin
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what is the intrinsic pathway of the coagulation system?
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Factor XII (Hageman factor) activage by contact with collagen in vivo and glass in vitro
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what is the extrinsic pathway of the coagulation system?
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Factor VII activated by tissue factor (thromboplastin) released from damaged tissue
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how is fibrin formed via the coagulation system?
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thrombin cleaves small peptides from fibrinogen, converting fibrinogen to fibrin, the fibrin polymerizes with other fibrin molecules on platelet surfaces, fibrin is cross-linked by factor XIII
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where do the intrinsic pathways and extrinsic pathways converge in the coagulation system?
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at Factor X but also because factor VII from extrinsic can activate IX from intrinsic
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what inhibits thrombosis?
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thrombomodulin, anti-thrombin III, tissue factor pathway inhibitor, endothelial cell factors, thrombin binding
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what does anti-thrombin III do?
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inactivates thrombin and factors Xa and IXa, loss of this protein blamed for clotting problems in kidney disease
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what endothelial cell factors inhibi thrombosis?
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PGI2, NO, ADP
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what does thrombin binding do to inhibit thrombosis?
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activates protein C for proteolysis of factors Va and VIIIa
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