Khan Academy on a Stick

  • Hemostasis

    Hemostasis is the process which stops bleeding after an injury. Blood vessels are repaired by the creation of a platelet plug during primary hemostasis, and the platelet plug is further reinforced by the conversion of fibrin to fibrinogen during secondary hemostasis.

  • Primary hemostasis

    During primary hemostasis, a platelet plug is formed to rapidly stop the initial bleeding after injury. Learn about the different steps involved in primary hemostasis: vasoconstriction, platelet adhesion, activation and degranulation, platelet aggregation.

  • Secondary hemostasis

    Secondary hemostasis is the process where the platelet plug initially created in primary hemostasis is reinforced by the conversion of fibrinogen to fibrin.

  • Anticoagulation and thrombolysis

    Anticoagulation is the process that prevents clots from forming. Thrombolysis is the process of breaking down clots after they’ve been formed. Learn how the antithrombin III interacts with heparin-like molecules and how plasmin breaks down fibrin.

Bleeding and impaired hemostasis