01
Primary Hemostasis
Vasoconstriction and platelet plug formation at the injury site
activates
An Interactive Lab for Hemostasis and Coagulation Testing
The Coagulation Cascade
Distinguish the classic laboratory cascade from cell-based hemostasis, predict PT/aPTT patterns, and reason through bleeding cases.
XII
XI
IX
X
II
I
IIa
Amplification
Intrinsic Pathway
Extrinsic Pathway
Common Pathway
Guided pathway
From mechanism to laboratory result
The app becomes easier when you study in sequence: distinguish the models, simulate screening tests, test your hypothesis, then review the details.
XII
VII
X
II
I
Overview
What is the Coagulation Cascade?
Hemostasis is a regulated network involving the vessel wall, platelets, coagulation proteins, natural inhibitors, and fibrinolysis. The classic cascade remains useful for organizing laboratory screening tests, while the cell-based model better represents physiology.
PT/aPTT
PT and aPTT map different parts of the classic model
TF
Tissue factor is the main physiological initiator
IIa
Thrombin amplifies coagulation on activated platelets
Flow
Hemostasis as a Coordinated Process
Hemostasis is a regulated network involving the vessel wall, platelets, coagulation proteins, natural inhibitors, and fibrinolysis. The classic cascade remains useful for organizing laboratory screening tests, while the cell-based model better represents physiology.
02
Secondary Hemostasis
The coagulation cascade activates to reinforce the platelet plug with fibrin
activates
03
Fibrinolysis
Controlled dissolution of the clot once healing is complete
Stable Fibrin Clot
Signals
Key Facts
Why amplification matters: the initial thrombin signal activates platelets and cofactors. Tenase (IXa–VIIIa) and prothrombinase (Xa–Va) then assemble on platelet surfaces and generate a thrombin burst.
PT/aPTT
PT and aPTT map different parts of the classic model
IIa
Thrombin amplifies coagulation on activated platelets
LAB
Reference intervals vary by reagent and laboratory
TF
Tissue factor is the main physiological initiator