Primary Haemostasis Flashcards
1
Q
What is the first step in primary haemostasis?
A
Tissue damage leads to exposed collagen, which causes VWF to bind
2
Q
What is VWF
A
Globular glycoprotein made in liver. Found in circulating plasma and in endothelial cells
3
Q
What receptor bind platelets to VWF?
A
GP1b. (Platelet adherence)
4
Q
What receptors weakly bind platelets to exposed collagen?
A
GP1a and GP6
5
Q
How to platelets aggregate?
A
VWF binding causes platelets to expose GP2b-GP3a. These can bind fibrinogen and more VWF.
6
Q
What is released in the platelet release reaction?
A
ADP and TXA2: attract more platelets. 5HT: local vasoconstriction
7
Q
What is bleeding time?
A
Time to form effective plug. Should be in 1-9 minutes; 13 in children
