Khan Academy on a Stick
Advanced hematologic system physiology
It takes between 30 seconds to a minute for your blood to travel from your heart, to your body, and back to the heart again - perhaps a bit longer if the trip is out to your big toe! Our blood is incredibly important for transporting oxygen throughout the body. Hemoglobin, the protein that fills our blood cells, has wonderful mechanisms to allow it to bind to both oxygen and carbon dioxide. This is important for effective and quick transport of the gases around our body. Our blood is about 45% cells and 55% plasma, so the old adage “blood is thicker than water” quite literally holds true in scientific terms! Learn more about how this amazing system works in the following videos.
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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.
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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.
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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.
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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.