Abstract
Preservation of the blood fluidity is a primary prerequisite for the maintenance of the circulation and consequently of life itself. The protection against loss of this fluidity is accordingly most effective. Since blood coagulation is a sequential process involving the successive activation of multiple proenzymes79,80 and since each activated enzyme is subject to neutralization in the plasma and cellular clearance, it must be extremely difficult to achieve a significant degree of activation of the later clotting factors in circulating blood. This interpretation of hemostatic homeostasis provides a theoretical basis for doubting blood coagulation as a continuous generalized process in vivo; it buttresses experimental evidence against the generalized coagulation hypothesis.81 Seen from a different perspective, the above concept of hemostatic homeostasis provides a teleological reason for the complexity of the coagulation process: Since so many steps are required, a great variety of independent mechanisms is available for controlling them, and there is corresponding safety in having the control mechanisms unavailable to total destruction by a single disrupting pathway.
