Hemostasis Flashcards
What is hemostasis?
Prevention of blood loss from broken vessel
What does hemostasis include?
Vascular spasm
Formation of a platelet plug
Blood coagulation
Clot retraction
Fibrinolysis
What is vascular spasm ( vasoconstrictions ) ?
Vasoconstriction of injured vessel due to contraction of smooth muscle in the wall of the vessel → this will reduce blood loss
What is formation of a platelet plug?
Occurs because platelets are exposed to collagen which as a result releases substances that causes the surfaces of nearby platelets to become sticky to form plug
What is blood coagulation?
Blood clots prevent the loss of blood from ruptured vessels
What is clot retraction?
Contraction of platelets trapped within clot shrinks fibrin meshwork, pulling edges of damaged vessel closer together
What is fibrinolysis?
Over time, the clot is dissolved and replaced with normal tissue
What does inappropriate clotting include?
Thrombus
Embolus
What is thrombus?
Clot formed in an intact vessel due to atherosclerosis and slow moving blood
What is embolus?
Moving clot
Presence of what prevents the blood from clothing?
Heparin and antithrombin III
What is responsible for removing blood clot ?
Fibrinolytic system
What are the two types of anticoagulants?
In vitro and in vivo
What anticoagulants in vitro include?
Decalcifying agents → Na+ or K+ bind with Ca2+ to stop clotting
Defibrination → removing fibrinogen and other coagulation factors
Cold → delays clotting
Addition of heparin
What anticoagulants in vivo include?
Heparin
Dicumarol
