The Hemostatic System — A “Lay” Summary of Old and New Observations

Abstract

The hemostatic system includes the cells (endothelial cells) which line the blood vessels, small corpuscles (platelets) which circulate with the white cells, and proteins (clotting factors) which circulate in the blood plasma. When all these components work together properly, the hemostatic system seals leaks in blood vessels by forming a blood clot at the injury site while remaining fluid everywhere else. When this system malfunctions, either no clot forms to seal the leak, resulting in hemorrhage, or clots form in vessels to the brain or heart where they are not required, resulting in thrombosis. The hemostatic system fulfills the complex task of forming clots in very specific areas while remaining fluid elsewhere. It does this by striking a balance between four basic functions: blood clot formation and prevention of blood clot formation; blood clot dissolution and the prevention of blood clot dissolution.