Coagulation Flashcards
5 main components of hemostatis
vascular system, platelet system, coagulation system, anti-coagulation system, fibrinolysis system
Function of vascular system
constriction by vascular reduces blood flow to site of injury. Slows flow of platelets passing by injury, allows for better change of adhesion
Function of platelets system
form platelet plus at injury sit. Release factors that can induce vasoconstriction.
Function of coagulation system
form fibrin clots, further stimulate platelet activation by producing thrombin
Function of anti-coagulation system
reduce thrombin formation and destroying thrombin that is already formed
Function of fIbrinolysis system
dissolve unnecessary clots formed in undamaged tissues, remove clots after injury has been healed
Names and ligands of main platelet glycoproteins that induce platelet adhesion/activation
GPIalpha - von Willebrand Factor
CPVI - collagen
GPIIa/IIIb - fibrinogen
Names and ligands of main G protein coupled receptors that induce platelet adhesion and activation
PSy12 - ADP
Protease activated receptor - thrombin
Thromboxane A2 receptor - Thromboxane A2
Function of ADP
further acitvate platelets
Function of serotonin
further activate platelets, cause vasoconstriction
Function of thromboxane A2
further activate platelets, cause vasoconstriction
Function of prostacyclin (PGI2)
induces vasodiliation, inhibits platelet adhesion and activation
Where is prostacycline (PGI2) formed
vascular endotherlial cells
What roles do platelets play in coagulation cascade
provide phospholipids that are used by coagulation factors, secrete factor V
How does thromobin activate platlets
activated protease activated receptors (PARs) on surface of platlets
Factor I (fibrinogen) function
converts fibrinogen into fibrin, forms fibrin blood clot
Factor II (prothrombin) function
becomes converted into thrombin which leaves fibrinogen, forming fibrin. also activates factor XIII into XIIIa, which induces crosslinking of fibrin fibers
Factor III (tissue) function
when injury takes place, it’s exposed to Factor VII contained in blood plasma, then binds to factor VII, activates to VIIa. Tissure cator, factor VIIa and Ca++ form a complex that activates Factor X into Factor Xa
Factor IV (Ca++)
acts as a cofactor with most coagulation factors
Which factors are vit K dependent
II, VII, IX, and X (1972)
proteins S, C, and Z
Connectives between platelet system and coagulation system
platelet phospholipids are sued by coagulation system
platelets release factor V which is part of coagulation system
coagulation system produces thrombin which binds to GPCRs on platelets, causing platelet activation
Components of anticoagulation system
thrombin/thrombomodulin complex, protein C, protein S, tissue factor inhibotr, antithrombin, herparin sulphate
How does heparin sulphate/heperain regulate thrombin and Factor Xa degradation
heparin binds to antithrobin III (AT) and activates it. AT inactivates thrombin and factor Xa, preventing coagulation initiation
How does thrombin/thromobomodulin complex reduce coagulation
bind to and activate protein C, a serine protease. Activated protein C interacts with protein S, inactivates Factors Va and VIIIa
Why does the factor V leiden mutation lead to hypercoagulable state
because this mutated factor V cannot be deactivated by APC
Components of fibrinolytic system
plasminogen, plasmin, tissue plasminogen activator, plasminogen activator inhibitor, alpha2 plasmin inhibitor
Plasminogen
zymogen that is converted into plasmin
Plasmin
active serine protease that can cleave fibbrin, thereby dissolving clots
tPA
activates plasminogen
PAI
removal and deactivation of tPA to prevent removal of necessary fibrin clots
alpha2 plasmin inhibitor
inhibits plasmin that is NOT already bound to fibrin in effect to negatively regulate the fibrinolytic system
