Blood Clotting Pathways Flashcards
What are the 3 steps of haemostasis?
1- Vascular spasm
2-Platelet Plug
3-Blood Coagulation
Why must haemostasis be appropriately controlled?
1- to avoid inappropriate clot formation
2-clots must be eventually degraded
3-clots are a temporary solution
Explain the 1st step in haemostasis - vascular spasm.
muscle cells of blood vessels contract after injury and VASOCONTRICTION occurs to reduce blood flow and limit blood loss.
What happens to opposing endothelial surfaces in the vascular spasm stage?
opposing endothelial surfaces are pressed together and adhere on contact
How is the vascular spasm stage mediated?
By platelet-derived products:
Serotonin
and
Thromboxane
What does normal endothelium produce?
vasoDILATORS and
inibitors of platelet aggregation -
e.g. protaglandin and nitric oxide