Lecture 5: Hemostasis Review Flashcards
What is the goal of hemostasis?
Keeping blood within a damaged blood vessel and is the first stage of wound healing.
What is hemostasis the balance between?
Procoagulant and anticoagulant factors.
What are the 4 phases of hemostasis?
- Initiation and formation of the platelet plug.
- Propagation of the clotting process by the coagulation cascade.
- Termination of clotting by antithrombotic control mechanisms.
- Removal of the clot by fibrinolysis.
What are the 3 main components in hemostasis?
Blood proteins (factors)
Platelets
Vessel wall (factors)
How long do endogenous platelets circulate?
~10 days
How long does it take to make a new batch of platelets?
3-5 days in the bone marrow.
How many platelets get pooled in the spleen?
1/3 of all platelets.
What is normal platelet count?
150k-450k
What are the dense granules in a platelet?
Serotonin
ADP
Ca
ATP
What are the alpha granules in platelets?
Platelet derived growth factor
Transforming growth factor beta
Fibrinogen
Von Willebrand factor
Platelet factor 4
Factor V
How do platelets promote clotting?
At the site of an active bleed, platelets will bind to exposed collagen to form the primary plug.
After forming the initial plug, addl plts recruited to expand and propagate the clot.
What happens once a platelet plug is made?
Clotting cascade begins with fibrin deposition
What hormone activates other platelets?
Thromboxane
Where is von willebrand factor synthesized and stored?
Endothelial cells
Platelets
What is the goal and unique characteristic of von willebrand factor?
Binds to other proteins
It is not an enzyme, so it does not need to be catalyzed.
What are the 3 functions of von willebrand factor?
- Binds to endothelium and promotes platelet adhesion to sites of vessel injury.
- Plasma carrier for Factor 8, preventing its degradation.
- Binds to collagen when exposed.
What releases factor 8 from vWF?
Thrombin
What is a deficiency in von willebrand factor linked to?
A factor 8 deficiency, aka hemophilia.