Haemostasis

Question 1

What is Haemostasis and how does it begin?

Answer 1

The process of stopping bleeding via clotting which begins with vasoconstriction. This increases the likelihood of contact between coagulation factors.

Question 2

What is primary haemostasis?

Answer 2

This involves platelets binding to Von Willebrand Factor VWF on the subendothelium and forming a plug

Question 3

What is secondary haemostasis?

Answer 3

This is the clotting cascade. The Intrinsic, extrinsic and common pathways.

N.B Thrombin is key in setting off the intrinsic by forming FXIa

The end point is Fibrin Ia

Question 4

What is fibrinolysis?

Answer 4

This is the process of breaking down fibrin to remove the clot

Question 5

What does APTT measure?

Answer 5

The intrinsic pathway, particularly 8, 9, 11, 12

Question 6

What does PT (INR) measure?

Answer 6

The extrinsic pathway, mainly 7

Question 7

What does TT measure?

Answer 7

The common pathway, fibrinogen to fibrin

Question 8

What does a D-Dimer measure?

Answer 8

Breadown products, so it is increased in a clotting sitation