Exam 1 – Dr. Thomason Hemostasis and Blood Coagulation Flashcards
What is hemostasis?
Prevention of blood loss from a vessel
What are the different mechanisms of hemostasis?
Formation of a platelet plug
Vascular constriction
Formation of a blood clot
Fibrinolysis
What are the 2 phases of hemostasis?
Primary hemostasis
Secondary hemostasis
What is primary hemostasis?
Interaction of vessels and platelets
What is the result of primary hemostasis?
Platelet plug
What is secondary hemostasis?
Clotting factors within coagulation cascade
What is the result of secondary hemostasis?
Blood clot
What is the size of platelets?
1-4 micron
Where do platelets form?
Bone marrow
How long do platelet circulate?
7-10 days
What are cytoplasmic factors?
Granules Calcium ions ATP and ADP Prostaglandins Growth factors
What are the 3 phases of platelet function?
Adhesion
Activation
Aggregation
What happens during platelet adhesion?
Circulate inactive along the periphery
Surface phospholipids detect and adhere to damaged vascular endothelium
First line of defense to prevent hemorrhage
What can adhesion lead to?
Platelet activation
What is von Willebrand’s factor (vWF)?
Adhesion protein produced by the endothelial cells and platelets
What is vWF associated with in plasma?
Factor VIII
What kind of trait is von Willebrand’s Disease (vWD)?
Autosomal
What are the predisposed breeds to vWD?
Doberman Pinchers
Standard Poodles
Shelties
German Shepherds
What will activated platelets do?
Change shape and size (grow pseudopods)
Express proteins to increase aggregation
Secret thromboxane A2
Contract and release granules
What does the release of granules in platelet activation do?
Recruit more platelets
What does thromboxane A2 cause?
Vasoconstriction
When does vasoconstriction occur?
Immediately after vessel damage
What does thromboxane over production cause?
Blood clots
What can aspirin do?
Block thromboxane synthesis
What does platelet aggregation do?
Attract additional platelets
Formation of a platelet plug
What kind of feedback is there in platelet aggregation?
Positive feedback loop
What happens with blood coagulation?
Initiation of coagulation cascade
Prothrombin becomes thrombin
Thrombin becomes fibrinogen into fibrin
Where are coagulation factors produced?
Liver
What are important players in hemostasis?
Prothrombin to thrombin
Fibrinogen to fibrin
Tissue factor
What is tissue factor released by?
Damage vascular endothelium when exposed to blood
What is tissue factor induced by?
Cytokines, endotoxins, and inflammatory mediators
What are the factors involved with the intrinsic portion of hemostasis?
8, 9, 11, and 12
What is involved with the extrinsic portion of hemostasis?
Factor 7
Tissue factor
What is involved with common portion of hemostasis?
Factor 5
Prothrombin to thrombin
Fibrinogen to fibrin
Cross-linked fibrin
What does thrombin do?
Amplifies the intrinsic to produce more thrombin
What kind of feedback is amplification?
Positive feedback loop
Describe hemostasis starting with tissue factor
Tissue factor will stimulate factor 7
Factor 7 will bind with factors 9 and 10
With the presence of factor 5, calcium, and factors 9 and 10, prothrombin becomes thrombin
After thrombin comes into play, amplification will come into play
What is hemostasis the balance of?
Coagulation and anticoagulation
What else can thrombin cause other than the amplification process?
The demise of hemostasis
It will activate plasminogen which causes everything else to decrease
What does fibrinolysis do?
Stops thrombin
Look at hemostasis chart
Look at hemostasis chart
What is hemophilia A?
Second most common inherited hemostatic defect
Common in German Shepherds
What does the severity of hemophilia depend on?
Factor deficiency
What is the treatment for hemophilia?
Cryoprecipitate
Plasma
What causes hemophilia A?
Deficiency in factor 8
What causes hemophilia B?
Deficiency in factor 9
What do anticoagulant rodenticides cause?
Rapid depletion of vitamin K-dependent factors
What are the vitamin K dependent clotting factors?
2, 7, 9, and 10
What is the liver the major site of?
Synthesis for coagulation factors