Haemostasis

Question 1

Haemostasis

Answer 1

Body’s physiological way of stopping blood loss from a damaged vessel.
Causes local vasoconstriction
Activates blood clotting

Question 2

Primary haemostasis (collagen)

Answer 2

Endothelial injury exposes collagen and tissue factor.

Collagen binds vWF and platelet GPIb receptors

Integrin receptors and GPVI receptors bind to collagen and initiate platelet activation

Question 3

Primary haemostasis (platelet activation)

Answer 3

Activated platelet extends pseudopodia and synthesises TXA2 mediated by COX1.

TXA2 binds to platelet GPCR P2Y12 receptors and causes mediator release and vasoconstriction

ADP binds to platelet GPCR P2Y12 receptors which activates further platelets and increases receptors that bind fibrinogen