Coagulation Flashcards
Where are coagulation factors produced?
Liver, factor 8 also can be made in endothelial cells
Zymogens coagulation factors (5)
2, 7, 9, 10, 11
Vitamin K dependent
2, 7, 9, 10
Procofactors (3)
TF, 5, 8
When you have an injury to endothelial cells, you activate primary hemostasis and expose
Tissue factor (TF)
You have a very small amount of this factor in its activated cleaved form that binds to TF to form a complex with calcium
7a
TF-7a complex cleaves these two factors
9a, 10a
What cleaves prothrombin to thrombin
10a
F2a
thrombin
What cleaves fibrinogen to fibrin?
Thrombin
What restructures the platelet’s phospholipid membrane so that factors can bind and interact?
Thrombin
In the presence of calcium, 9a forms a complex with this factor
8a
9a-8a complex actives more of this factor, which subsequently forms a complex with what factor? (in presence of calcium)
10a, forms a complex with 5a. Cleaves prothrombin to thrombin much more aggressively
What factor is critical for crosslinking? What activates it?
13a, thrombin
List the 3 main functions of thrombin
- cleaves 5, 8, 11, 13
- Cleaves fibrinogen to fibrin
- Restructures platelet phospholipid membrane
Which two complexes bind to platelet?
5-10, 8-9
These residues are responsible for the high-affinity binding of calcium ions and interaction with platelet membrane
Gla residues (gamma-carboxyglutamate)
What is the role of the vitamin K dependent carboxylase?
carboxylates glutamic acid resides to gamma carboxy glutamic acid (gla)
Thrombin restructures platelet membrane to expose the net negative charge of this component
PS (phosphotidylserine)
In forming a carboxylated prozmogen, Vitamin K converts from what state?
Reduced to Oxidized
Epoxide reductase converts oxidized vitamin K to its reduced form. What are two blockers of this step? What are the consequences of this blockage
Coumadin and warfarin. If cant bring Vitamin K back to reduced form, it cant carboxylate and can’t function/clot as well. Have thinner blood
Prothombin time evaluates which pathway?
Extrinsic pathway
What is the only factor involved in the extrinsic pathway?
TF
In prothrombin time, the specimen is collected in this to remove calcium
citrate (can bind to calcium)
This was created to standardize the PT results across labs, since TF reagants are variably thrombogenic
International Normalized Ratio (INR)
What’s a normal INR? What’s a typical therapeutic INR?
normal=1, therapeutic=2-3
Partial thromboplastin time evaluates which pathway? What does it not include?
Intrinsic, no TF
PTT is used for monitoring
unfractured heparin