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37 Cards in this Set

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

Extrinsic: Tissue thromboplastin
What factor is Thrombin?
Factor IIa
What are the 6 actions of thrombin (2a)?
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
What is the purpose of Protein C?
To keep the clotting reaction confined to an immediate area.
What is the purpose of fibrinolysis?
To return the vasculature to its normal, smooth state.