MODULE Flashcards
In Vivo Coagulation
Tissue factor
Platelets
In Vitro Coagulation
Activation of Factor XII
Two phases of coagulation:
Initiation
Propagation
COAGULATION REGULATORY MECHANISMS
TAFI
PROTEIN C RUGULATORY SYSTEM
COAGULATION REGULATORY PROTEINS
Antithrombin
Heparin Cofactor II
Protein Z
Protein C inhibition
● clot dissolution to keep blood vessels free from deposited fibrin and fibrin clots
● occurs when plasminogen is converted to plasmin.
● if it occurs excessively, it can cause bleeding
● if it occurs inadequately, it can lead to thrombosis
FIBRINOLYSIS
Activators of Fibrinolysis
Tissue Plasminogen Activator
Urokinase Plasminogen Activated
occurs on tissue factor-expressing cells
Initiation
produces 3% - 5% of the total thrombin generated
Initiation
occurs on platelets
Propagation
produces 95% or more of the total thrombin generated
Propagation
principal regulator of the tissue factor pathway
TAFI
revises thrombin’s function from a procoagulant enzyme to an anticoagulant
Protein C regulatory system
first to be identified; inhibits Factor IIa, IXa, Xa, XIa, XIIa, PK, Plasmin
Antithrombin
inactivates thrombin
Heparin cofactor II
dependent protease inhibitor - potent inhibitor of Factor Xa; also inhibits Factor XIa
Protein Z
inhibits APC, IIa, Xa, XIa, urokinase
Protein C inhibitor
two glycosylated kringle regions
TPA
the principal inhibitor of plasminogen activators TPA and UPA
PAI-1
primary inhibitor of free plasmin
A2- antiplasmin
becomes activated by the thrombin-thrombomodulin complex
Thrombin
inhibits fibrinolysis by preventing the binding of TPA and plasminogen to fibrin, and blocking the formation of plasmin.
Thrombin
D-E-D
Fragment X
D-E
Fragment Y
