1. Clot Formation Review with Animations
Nicole L. Draper, MD

2. Clot Formation Initial Steps
Primary Hemostasis
Adhesion
Activation (2 & 3)
Aggregation
Robbins Basic Pathology, 9th Edition

3. Y Y 1-Endothelial cell injury 5- Granule release reaction-
3- vWF allows adhesion of
platelet to subendothelium
via GPIb
1-Endothelial
cell injury Y Y
5- Granule release reaction-
Secretion of ADP, serotonin
& calcium cause more
platelets to activate and aggregate.TxA2 synthesis.
ADP
2-Release of
Tissue Factor
begins extrinsic
pathway of coag-
ulation cascade.
ECM
exposure.
6- Coagulation cascade
produces fibrin strands
That trap and enmesh
the platelets and other cells into a thrombus.
4- Fibrinogen bridges
form by binding GPIIb/IIIa
on the platelet membrane
(Initial aggregation).

4. Normal Secondary Hemostasis
Coagulation Factors
Anti-fibrinolytic System
Coagulation Factors
Anti-fibrinolytic System
Natural Anticoagulants
Fibrinolytic System
Natural Anticoagulants
Fibrinolytic System
Anticoagulation and clot breakdown
Clot formation and maintence

5. Secondary Hemostasis XII XI IX + VIII VII X + V Antithrombin
Negatively Charged Surface
(exposed ECM or activated plt)
VII
X + V
Tissue factor from ECM
Antithrombin
Tissue Factor Pathway Inhibitor
heparins
Platelets
Thrombomodulin
Protein C/
Protein S II
Fibrinogen
XIII
Stable fibrin clot