Principles of haematology

Question 1

Intrinsic pathway

Answer 1

• activated by damage inside the vasculature exposing collagen
• 12 > 11 > 9 (+8) > common pathway
• measured by APTT

Question 2

Extrinsic pathway

Answer 2

• activated by external trauma
• vascular damage leads to tissue factor release
• factor 7 leads to factor 10 activation
• measured by PT

Question 3

Common pathway

Answer 3

• factor 10 and 5 convert factor 2 (prothrombin) into factor 2a (thrombin)
• thrombin converts factor 1 (fibrinogen) into factor 1a (fibrin)
• fibrin + factor 13a + Ca2+ make a clot

Question 4

Primary platelet plug formation

Answer 4

• von Willebrand factor binds to subendothelial collagen where there is tissue damage
• vWF then unravels and binds to GP1b on platelets, leading to platelet capture

Question 5

D-dimer

Answer 5

a fibrin degradation product made when a clot is degraded by fibrinolysis

Question 6

Myeloid lineage

Answer 6

• megakaryocyte > platelets
• erythroblast >reticulocyte >erythrocyte
• myeloblast > monocyte (> macrophage), basophil, eosinophil, neutrophil
• mast cells

Question 7

Lymphoid lineage

Answer 7

• Lymphoblast > NK cell or lymphocyte
• Lymphocyte > B cell (> plasma cell), T cell