Haemostasis

Question 1

What is haemostasis?

Answer 1

The arrest of bleeding and the maintenance of vascular patency

Question 2

How are platelets formed?

Answer 2

Formed in the bone marrow by ‘budding’ from megakaryocytes

Question 3

What is the lifespan of a a platelet?

Answer 3

7-10 days

Question 4

What causes platelets recruitment?

Answer 4

Endothelial damage exposes collagen and releases VWF and other proteins to which platelets have receptors

Question 5

What are the consequences of failure of platelet plug formation?

Answer 5

Spontaneous bruising and purpura
Mucosal bleeding
Intracranial haemorrhage
Retinal haemorrhages

Question 6

What is the screening test for primary haemostasis?

Answer 6

Platelet count

Question 7

What is the intrinsic pathway?

Answer 7

TF activates Factor VIIa - Activates factors V/Xa which converts prothromin to thrombin which converts fibrinogen to fibrin to form a clot

Question 8

What is the extrinsic pathway?

Answer 8

Factors VII/IX stimulate factors V/Xa which converts prothrombin to thrombin which converts fibrinogen to fibrin and also potentiates factors VIII/IX

Question 9

What breaks down Fibrin to FDPs?

Answer 9

Plasmin

Question 10

What converts plasminogen to plasmin?

Answer 10

Tissue Plasminogen Activation (tPA)

Question 11

Which drugs activate tPA?

Answer 11

Fibrinolytic drugs

Question 12

What causes d-dimers to go up?

Answer 12

Blood clot formed so more Fibrin being broken down to FDPs

Question 13

What tests are used to screen for fibrin clot formation?

Answer 13

PT

APTT

Question 14

Name the naturally occurring anticoagulants?

Answer 14

Anti-thrombin III

Protein C & Protein S