explain the different stages involved in blood coagulation
Answers
Explanation:
Hemostasis is the natural process that stops blood loss when an injury occurs.
Explain the steps involved in hemostasis
Key Points
Hemostasis is the natural process that stops blood loss when an injury occurs.It involves three steps: (1) vascular spasm ( vasoconstriction ); (2) platelet plug formation; and (3) coagulation.
Vasoconstriction is a reflex in which blood vessels narrow to increase blood pressure.
Next, platelet plug formation involves the activation, aggregation, and adherence of platelets into a plug that serves as a barrier against blood flow.
Coagulation involves a complex cascade in which a fibrin mesh is cleaved from fibrinogen.
Fibrin acts as a “molecular glue” during clot formation, holding the platelet plug together.
Key Terms
hemostasis: The process of slowing and stopping the flow of blood to initiate wound healing.
coagulation: The process by which blood forms gelatinous clots.
heparin: A fibrinolytic molecule expressed on endothelial cells or produced as a blood thinner medicine. It prevents activation of platelets and clotting factors.
Hemostasis is the natural process in which blood flow slows and a clot forms to prevent blood loss during an injury, with hemo- meaning blood, and stasis meaning stopping. During hemostasis, blood changes from a fluid liquid to a gelatinous state.
Steps of Hemostasis
Hemostasis includes three steps that occur in a rapid sequence: (1) vascular spasm, or vasoconstriction, a brief and intense contraction of blood vessels; (2) formation of a platelet plug; and (3) blood clotting or coagulation, which reinforces the platelet plug with fibrin mesh that acts as a glue to hold the clot together. Once blood flow has ceased, tissue repair can begin.
Angiogenesis Generates New Blood Vessels: Blood vessel with an erythrocyte (red blood cell) within its lumen, endothelial cells forming its tunica intima or inner layer, and pericytes forming its tunica adventitia (outer layer).
Vasoconstriction
Intact blood vessels are central to moderating blood’s clotting tendency. The endothelial cells of intact vessels prevent clotting by expressing a fibrinolytic heparin molecule and thrombomodulin, which prevents platelet aggregation and stops the coagulation cascade with nitric oxide and prostacyclin. When endothelial injury occurs, the endothelial cells stop secretion of coagulation and aggregation inhibitors and instead secrete von Willebrand factor, which causes platelet adherence during the initial formation of a clot. The vasoconstriction that occurs during hemostasis is a brief reflexive contraction that causes a decrease in blood flow to the area.