Bleeding & Clotting Disorders

Hemostasis: the platelet plug + the fibrin mesh · Week 9
Stopping a bleed takes two steps. First, platelets pile up to form a quick plug. That needs platelets and von Willebrand factor. Then clotting factors weave a fibrin mesh to lock the plug in place. Too little of either → bleeding. Too much → clots. Click a disorder to see which step breaks.

How a clot forms, and where it fails

The step that fails turns red. Bleeding disorders break an early step. Clotting disorders overdo it.
Pick a disorder to see where hemostasis breaks down.
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Thinning the blood: the two anticoagulants

💧 Heparin
Works on the fibrin-mesh step. It boosts antithrombin, which shuts down thrombin and factor Xa. It acts fast, is given IV or by injection, and is tracked with the aPTT. Note: heparin can itself cause thrombocytopenia, called HIT.
💊 Warfarin
Stops the liver from making the vitamin-K clotting factors (II, VII, IX, X). It is slow to work, taken by mouth, and tracked with the PT/INR.