Clot FormationReview with Animations

Nicole L. Draper, MD

Primary HemostasisAdhesionActivation (2 & 3)Aggregation

Clot Formation Initial Steps

Robbins Basic Pathology, 9th Edition

Y Y

4- Fibrinogen bridgesform by binding GPIIb/IIIaon the platelet membrane(Initial aggregation).

2-Release ofTissue Factorbegins extrinsicpathway of coag-ulation cascade.ECM exposure.

1-Endothelial cell injury

3- vWF allows adhesion of platelet to subendothelium via GPIb

5- Granule release reaction-Secretion of ADP, serotonin& calcium cause more platelets to activate and aggregate.TxA2 synthesis.

6- Coagulation cascadeproduces fibrin strandsThat trap and enmesh the platelets and other cells into a thrombus.

Y YADP

Natural AnticoagulantsFibrinolytic System

Coagulation FactorsAnti-fibrinolytic System

Normal Secondary Hemostasis

Coagulation FactorsAnti-fibrinolytic System

Natural AnticoagulantsFibrinolytic System

Clot formation and maintence

Anticoagulation and clot breakdown

Secondary Hemostasis

II

Fibrinogen

XIII Stable fibrin clot

Platelets

VII

X + V

Tissue factor from ECM

XII

XI

IX + VIII

Negatively Charged Surface(exposed ECM or activated plt)

Thrombomodulin

Protein C/Protein S

Antithrombin

Tissue Factor Pathway Inhibitor

heparins