1. BLOOD COAGULATION CASCADE
• .
1
Intrinsic pathway
Blood disturbances and platelet
phospholipids activate factor XII
to initiate the intrinsic
coagulation pathway, which
leads to the activation of
(factor X).X
Extrinsic pathway
When a vessel is injured,
(tissue factor, or
thromboplastin) is released
from the endothelium
initiating the extrinsic
coagulation pathway, which
leads to the activation of
(factor X).
TF
X
Common pathway
(factor II, or prothrombin) is converted by
factor Xa into factor IIa, or thrombin.
Thrombin cleaves (factor I, or fibrinogen) to
form fibrin (factor Ia), a key component of clot
formation.
II
I
Adapted from Ansell J. J Thromb Haemost. 2007;5(suppl1):60-64.
Guyton AC, Hall JE. Hemostasis and blood coagulation. In: Textbook of Medical Physiology. 10th ed. Philadelphia, PA: WB Saunders Co;
2000:419-429.
Moake JL. Hemostasis. In: Porter RS, Kaplan JL, Homeier BP, eds. The Merck Manual Online. http://www.merck.com/mmpe/sec11/ch134/ch134a.html. Accessed March
4, 2008.
Fibrin Clot
Xll
Xl
lX
VIIIa VII
TF
Va
II
I
X
