8 Questions
What is the primary function of hemostasis in the body?
To prevent blood loss and maintain blood fluidity
What is the result of defects in hemostasis?
Increased risk of bleeding or clotting
What is the primary hemostasis?
Formation of platelet plug
What is the role of thrombin in the coagulation cascade?
To convert fibrinogen to fibrin
What is the purpose of the fibrinolytic system?
To dissolve fibrin clot
What is the definition of bleeding time?
The time interval between skin puncture and spontaneous stoppage of bleeding
What is the activator of the coagulation cascade?
All of the above
What is the product of the conversion of fibrinogen in the coagulation cascade?
Fibrin
Study Notes
Hemostasis Physiology
- Hemostasis is the process of forming clots in damaged blood vessels to prevent blood loss while maintaining blood fluidity within the vascular system.
- Defects in hemostasis can lead to increased risk of bleeding (hemorrhage) or clotting (thrombosis).
Events in Hemostasis
- Vascular constriction: damaged blood vessels constrict.
- Formation of platelet plug: platelets adhere to damaged endothelium to form a platelet plug (primary hemostasis).
- Blood coagulation: clots form upon the conversion of fibrinogen to fibrin, and its addition to the platelet plug (secondary hemostasis).
The Clotting Mechanism
- The intrinsic pathway involves collagen, XII, XI, IX, VIII, and X.
- The extrinsic pathway involves tissue thromboplastin, VII, X, and V.
- Fibrinogen (I) is converted to fibrin, leading to the formation of a blood clot.
- Prothrombin (II) is converted to thrombin (III), which facilitates the conversion of fibrinogen to fibrin.
Fibrinolytic Phase
- The fibrinolytic system prevents the growth of a fibrin clot, which would cause serious complications.
- Fibrinolysis (dissolving of fibrin fibers) is brought about by the formation of active enzyme plasmin from plasminogen.
Bleeding Time (B.T.)
- Definition: the time interval between skin puncture and spontaneous, unassisted stoppage of bleeding.
Learn about the process of hemostasis, its definition, and the importance of blood clotting in the vascular system. Understand the risks of bleeding and thrombosis due to defects in hemostasis.
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