Clotting Flashcards
What causes the clotting cascade to start?
Injury to endothelium
What is primary hemostasis?
A localized platelet plug formed at endothelial injury
What is secondary hemostasis?
When more stuff is added to primary hemostasis, such as: fibrin (Factor 1) –> coagulum
Platelet plug + Coagulum = clot
What 2 things do you need to form a clot?
Platelet plug + Coagulum.
What is an antithrombiss?
Inhibition of clotting
What is Fibrinolysis?
Breakdown and removal of clot
What autonomic event happens when there’s an injury to the endothelium?
Vasoconstriction
What substance drastically accelerates production of fibrin 1000 fold?
Phospholipid platform formed during secondary hemostasis
sticky activated platelets
What starts off Extrinsic pathway?
What factors are in the extrinsic pathway?
7 being turned into 7a via injury. Injury lets off Tissue Factor (Thromboplastin/F).
7, 3, X (3=TF)
What is the overall goal of the extrinsic pathway?
To create Xa that goes in prothrombinase.
What enzyme must be created to form Xa from the extrinsic pathway?
The Complex of TF - 7a - Ca++
What enzyme must be created to form Xa from the intrinsic pathway?
Tenase. Contains: 9a 8a Ca++
What enzyme does the intrinsic and extrinisc pathway meet at?
Prothrombinase
Xa
Va
Ca
What does Prothrombinase do?
Makes thrombin from prothrombin via thrombine.
What is the overall goal of the clotting cascade?
To make stable, polymer fibrin (factor 1).
Once you have fibrin monomers, what final factor do you need to get your product?
13 –> 13a via thrombine.
Which factors are Vitamin K dependent?
2, --> (Thrombin) 7, 9, X Protein S and C
“1972”
How is the intrinsic pathway began?
Platelets conformational change to show the phospholipid- rich platform
How does the phospholipid platform initiate intrinsic cascade?
The Phospholipid platform is negatively charged, which attracts Factor 12 and HMWK
Factor 12 –> Factor 12a is accelerated by what 2 things?
HMWK & Kallikrein
If there’s a problem in your Factor 9 or Factor 8, what disease do you have?
Haemophilia
In general, what factors are used in what order of intrinsic?
12- 11- 9 - 8 -10.
What is the end product of the intrinsic pathway
Tenase
9a
8a
Ca++
What are thrombin’s 3 roles?
- Activate downstream components (look at diagram)
- Positive feedback upstream
- Paracrine activity
What is the paracrine activity caused by Thrombin?
Causes endothelin cells to release NO, Prostacyclin, (Vasodilators) and TPA (Tissue plasminogen activator –> dissolves clots)
What part of the blood is used in Hemostasis testing?
What is the tube cap color?
Plasma
Blue
What are the most common causes of prolonged aPTT?
Med OD: heparin, oral anticog
Dilutional coagulopathy (Bleeding out)
Inherited: Haemophilia
DIC: Disseminated INtravascular Coagulation
What does Warfarin do?
Inhibit Vitamin K = Spontaneous bleeding b/c no clots
Warfarin: same.
More specifically inhibiting epoxide reductase