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🩹 Blood Clotting Cascade

A simplified coagulation cascade activates thrombin and fibrin at a wound site while platelet particles aggregate against simulated blood flow, forming a clot mesh that seals the injury.

Biology & Life2DEasy60 FPS

How it Works

A vessel channel carries platelet particles downstream under a simulated blood flow. A wound breaches the lower vessel wall and exposes tissue factor, which drives a simplified four-stage coagulation cascade: tissue factor activates factor X, factor X activates prothrombin into thrombin, and thrombin converts fibrinogen into fibrin. Each stage is modelled as a relaxation toward the concentration of the stage before it, scaled by the cascade activation rate and slowed by the anticoagulant level slider — exactly how real anticoagulant drugs work, by damping the rate constants of the clotting enzymes rather than blocking them outright.

Once local fibrin concentration near the wound crosses a threshold, the wound is primed for clotting: platelets that flow close enough to the breach stop moving and stick in place, and any platelet that later drifts within a short bonding radius of an already-stuck platelet joins the mesh too. This chain reaction lets a plug grow outward from the wound edges even though only nearby platelets ever interact, and once the aggregated mesh spans the full width of the breach the wound is marked sealed.

Cascade step: stage[i] += rate·(1-anticoagulant)·(stage[i-1] - stage[i])
Stages: TissueFactor → FactorX → Thrombin → Fibrin
Platelet sticking: if fibrin > 0.5 and platelet within woundRadius → velocity = 0
Mesh growth: stuck platelet bonds any free platelet within 7px of it

Frequently Asked Questions

What is the coagulation cascade?

The coagulation cascade is a chain of enzyme-activation steps in blood plasma that starts when tissue is damaged and ends with the protein fibrin forming a mesh that, together with platelets, seals the wound.

Why does the simulation show four sequential bars?

Each bar represents one simplified stage of the real cascade — tissue factor, factor X, thrombin and fibrin — where each stage only rises once the one before it has built up enough concentration, reproducing the amplifying, sequential nature of coagulation.

How do platelets form a plug?

Once fibrin concentration near the wound crosses a threshold, platelets flowing past stick in place instead of continuing downstream, and any further platelets that drift within a short distance of an already-stuck platelet bond to it too, building an expanding mesh.

What does the anticoagulant slider represent?

It represents drugs or natural factors, like heparin or antithrombin, that slow the rate constants of the cascade. A high anticoagulant level delays or even prevents thrombin and fibrin from ever crossing the clotting threshold.

What does it mean for the wound to be sealed?

The wound is marked sealed once enough aggregated platelets span the full width of the breach in the vessel wall, physically blocking further blood loss through that opening.

About this simulation

Four small bars in the corner of the canvas are quietly doing all the real work: watching tissue factor slowly wake up factor X, which wakes up thrombin, which finally converts fibrinogen to fibrin, makes visible the amplifying relay race that turns a tiny nick in a vessel wall into a physical plug within seconds.

🔬 What it shows

A four-stage coagulation cascade driving local fibrin concentration at a wound site, which in turn triggers passing platelets to stick and progressively mesh together into a sealing plug.

🎮 How to use

Increase Wound Size and Blood Flow Rate to make sealing harder, then raise Cascade Activation Rate or lower Anticoagulant Level to see how quickly the clot can catch up and seal the breach.

💡 Did you know?

Warfarin and heparin, two widely used anticoagulant drugs, work by slowing exactly the kind of rate constants this simulation's anticoagulant slider represents, which is why patients on them bruise and bleed more easily.

Frequently asked questions