[The physiology of hemostasis: plasma and tissue factors in coagulation and fibrinolysis].
Coagulation and fibrinolysis are two antagonistic phenomena, the harmonious balance of which results form a perfect regulation of their respective activators and inhibitors. Indeed, the efficacy of the response of the organism to an aggression against the blood vessel and its plasmatic and cellular contents, depends on the capacity of maintaining this balance. The mechanisms involve plasma proteins (factors) endowed with a proteolytic activity, as well as mediators released from injured tissues (endothelium). Coagulation corresponds to the process of fibrin formation (fibrin clump), which assures the consolidation of the platelet clot which was pre-formed during the activation of the platelets. Fibrinolysis consists in the gradual dissolution of this fibrin clump, aimed at re-permeabilization of the vessel at the site of the lesion, and thus at a normalization of the blood circulation at this level. Coagulation and fibrinolysis can hardly be dissociated from primary haemostasis (platelet activation), not only because of their interactions, but also because of their chronology: all these events are, indeed, triggered almost simultaneously, even though the duration varies. The mechanisms that are implicated in thrombo-embolic phenomena are comparable to those of physiological haemostasis. However, it is the imbalance between these events which constitutes the pathological aberration and thus induces the formation of a fibrin-platelet thrombus.
François
P
P
Verstraeten
L
L
Dinant
J P
JP
D001777:Blood Coagulation; D005342:Fibrinolysis; D006487:Hemostasis / Q000502:physiology*; D006801:Humans
Physiologie de l'hémostase: facteurs plasmatiques et tissulaires de la coagulation et de la fibrinolyse.