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37 Cards in this Set
- Front
- Back
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Define hemostasis
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the balance between clotting and lysing.
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Define the hemostasis mechanism
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the property of the circulatory system whereby fluid is maintained within the blood vessels.
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How do the vessels/plts/coag factors interact? (3 things)
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1. Vessels have FAST graded response.
2. Platelets form the plug 3. Coag/fibrinolytic factors hold it all together. |
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what 3 additional systems interact w/ coag factors?
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1. Kinin system
2. Serine protease inhibitors 3. Complement system |
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What composes the kinin system and what is the most important one?
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-Small peptides.
-Bradykinin is most important. |
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What are the 2 main actions of bradykinin?
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-Vascular permeability
-Pain mediator |
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What activates bradykinin?
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Factor 2
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What ARE the serine protease inhibitors?
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Natural anticoagulants that dampen the coag response.
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Name 4 serpins.
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1. AT-III
2. Heparin cofactor II 3. alpha-2-trypsin 4. a2-macroglobulin |
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How does the complement system interact w/ the coag cascade?
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-Interface between the 2 systems
-Mediates immune/allergic response. |
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What activates the complement system?
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Plasma
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What are the 2 types of properties of the vasculature that are involved with coagulation?
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1. Procoagulant
2. Anticoagulant |
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What are the procoagulant PROPERTIES of the vasculature? (3)
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1. Vasoconstriction to divert blood flow in capillaries.
2. Initiates contact activation. 3. Endothelial cells -> vWF |
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What are the anticoagulant PROPERTIES of the vasculature? (3)
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1. Thrombomodulin activates protein C.
2. Tissue factor pathway 3. Vessels have a smooth surface for blood flow. |
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The 3 areas of interaction btwn the Vasculature/hemostasis are:
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1. Endothelial cell lining
2. Subendothelium 3. Vasoconstriction |
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How does the vessel endothelial cell lining affect hemostasis? (3 properties)
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1. Prostacylin (PGI2)
2. Tissue fluid 3. ADP |
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What are the 2 actions of Prostacylin from the EC lining?
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1. Inhibition - disaggregates platelets and prevents clot.
2. Vasodilation - opens blood vessel, preventing |
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How does tissue fluid from the EC lining interact w/ clotting?
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Contains coagulant factors, will initiate the process.
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How does ADP from EC lining affect clotting?
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It inhibits the calcium receptor, thus increases cytoplasmic Calcium.
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What property of the SUBendothelium affects clotting?
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Its collagen attracts platelets, thus helping with coagulation.
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What causes vasoconstriction?
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Nerve reflex - thus it's instantaneous.
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How does vasoconstriction enhance platelets?
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It releases TxA2, thromboxane.
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What is Thromboxane?
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a Potent Platelet Aggregator and antagonist of prostacyclin.
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What is thromboplastin?
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Factor present in tissues that aids Fx VIIa in activating Fx X via the extrinsic cascade.
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What 6 products from vasoconstriction affect coag?
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1. TxA2 (Thromboxane) PRO
2. ADPase - Anti 3. ADP - PRO 4. vWF - PRO 5. Plasminogen activator Anti 6. Thromboplastin PRO |
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What stage of hemostasis do platelets affect?
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PRIMARY
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What are the 5 actions of platelets in coagulation?
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1. Adhere to subendothel via vWF
2. Primary aggregation (reversible) 3. Scndry aggr (nonreversible) 4. "Release reactions" 5. Platelet surface |
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What 3 substances do platelets release in their granules?
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1. Thromboxane A2
2. SErotonin 3. ADP |
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again, what is TxA2's action?
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-Potent platelet aggregator
-Antagonist of prostacyclin. |
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What does Seretonin do?
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Aids in aggregation
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What is the role of ADP when released from platelets?
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-Released from dense bodies
-Recruit more platelets from the storage pool. |
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What is on the SURFACE of platelets?
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1. Negative charge
2. Heparin sulfate 3. PGI2 |
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What is the activator of the:
-Intrinsic pathway -Extrinsic pathway |
Intrinsic: EXposed collagen
Extrinsic: Tissue thromboplastin |
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What factor is Thrombin?
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Factor IIa
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What are the 6 actions of thrombin (2a)?
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1. Activates plt aggregation
2. Activ. INTRINSIC by Fx XII 3. Converts Fibrinogen->fibrin 4. Activates Fx XIII to stabilize the fibrin clot. 5. Activates Protein C 6. Activates V->Va/VIII->VIIIa |
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What is the purpose of Protein C?
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To keep the clotting reaction confined to an immediate area.
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What is the purpose of fibrinolysis?
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To return the vasculature to its normal, smooth state.
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