Blood Clotting Pathways

Question 1

What are the 3 steps of haemostasis?

Answer 1

1- Vascular spasm
2-Platelet Plug
3-Blood Coagulation

Question 2

Why must haemostasis be appropriately controlled?

Answer 2

1- to avoid inappropriate clot formation
2-clots must be eventually degraded
3-clots are a temporary solution

Question 3

Explain the 1st step in haemostasis - vascular spasm.

Answer 3

muscle cells of blood vessels contract after injury and VASOCONTRICTION occurs to reduce blood flow and limit blood loss.

Question 4

What happens to opposing endothelial surfaces in the vascular spasm stage?

Answer 4

opposing endothelial surfaces are pressed together and adhere on contact

Question 5

How is the vascular spasm stage mediated?

Answer 5

By platelet-derived products:

Serotonin
and
Thromboxane

Question 6

What does normal endothelium produce?

Answer 6

vasoDILATORS and
inibitors of platelet aggregation -

e.g. protaglandin and nitric oxide