Topic 5.2 Flashcards
What does heparin sulfate do?
bind antithrombin 3
What is the role of antithrombin 3?
degrades clotting factors 2, 9, 10
Which drug can increase antithrombin activity?
heparin
What is the role of thrombomodulin?
bind thrombin
What is another name of thrombin?
factor 2
What does thrombin-factor 2 do?
activates protein C
What does protein C do?
it degrades clotting factors 5 and 8
What are the 5 mechanisms of hematostasis?
- Vascular spasm
- Platelet plug
- Coagulation
- Clot retraction and repair
- Fibrinolysis
What are the 2 ways of SM contraction if damage occurs?
- endothelin secreted by endothelial cells
- stimulation of nociceptors by inflammatory chemicals
What produced VWF?
injured endothelial cells
How do platelets bind to VWF?
with the GpIb on their membrane
What 3 things do platelets release when activated?
ADP, TvA2, serotonin
What do TxA2 and ADP do?
they stimulate other platelet aggregation to site of injury
How do platelets bind together?
Gp IIb/IIIa and their membranes and fibrinogen (factor 1)
What do serotonin and TxA2 cause?
contraction by binding to SM (vascular spasm)
What happens once the platelet plug is formed?
phosphatidyl serines on the surface of the plug create a negative charge that activated factor 13
Which organ produces clotting factors?
mostly the liver
What does factor 13 do?
activated factor 12
What does factor 12 do?
Activates factor 11
What does factor 11 do?
Activated factor 9
What does factor 9 do?
forms a complex with factor 8 and together they activate factor 10
What is needed to form the factor 9/factor 8 complex?
PF3 and Ca2+
What does factor 10 do?
reacts with factor V and activates prothrombin activator
Which steps need cofactors?
- Factor 9 and 8 complex formation
- Factor 10 and 5 interaction
What does the prothrombin activator do?
activates prothrombin into thrombin
What is another name for thrombin?
factor II
Which drug can inhibit TxA2?
aspirin, by inhibiting cox 1
Which drug can inhibit ADP?
clopidogril
What are the 2 roles of thrombin?
- Polymerize fibrinogen into insoluble fibrin
- activates factor 13
What is another name for factor 13?
fibrin stabilizing factor
What is the role of factor 13?
cross links the fibrin strands to form the fibrin mesh
What does the fibrin mesh do?
holds the platelet plug in place + slows down blood flow
What is the extrinsic pathway?
- factor 3 activated factor 7
- factor 7 either activates 10 directly or activated 9
What is another name for factor 3?
tissue factor
How long does the extrinsic pathway take?
30 seconds, fast
How long does the intrinsic pathway take?
2-5 minutes, slow
Which 2 factor do platelets release for clot retraction and repair?
- PDGF (platelet derived growth factor)
- VEGF (vascular endothelial growth factor)
What does PDGF do?
triggers mitosis of SM to repair lining + produces CT patches
What does VEGF do?
regenerates endothelial lining
Which protein on the endothelial cell membrane triggers fibrinolysis?
TPA (tissue plasminogen activator)
What does TPA do?
activates plasminogen into plasmin
What does plasmin do?
digests and degrades the fibrin mesh
What is released after degradation of fibrin mesh? (2)
fibrinogen + D-dimer
What is the role of warfarin?
inhibits vitamin K so that you can’t produce coagulation factors
