Clotting Cascade Flashcards
1
Q
What factors/factors are exclusive to the extrinsic pathway?
A
Factor VII (7)
2
Q
What factor/factors are exclusive to the intrinsic pathway?
A
Factora XII, XI, IX, and VIII (12,11,9,8)
3
Q
What factors are in the common pathway?
A
Factor I, II, V, X (1,2,5,10)
4
Q
What is the goal of primary hemostasis?
A
To form a platelet plug
5
Q
What is the goal of secondary hemostasis?
A
Make platelet plug stronger by covering it in a fibrin mesh
6
Q
- What does thrombin do?
A
- Converts fibrinogen to fibrin
- Activates factor XII (XIIa)
- Aids in conversion from prothrombin to thrombin
- ACtivates Factor V (Va)
- Activates Factor VIII (VIIIa)
7
Q
- Which factor, when interacting with Ca2+ helps form fibrin cross links?
A
Factor XIIa
8
Q
- What factors depend on vitamin k for activation
A
Factor II
Factor VII
Factor IV
Factor X
9
Q
- What else does vitamin k activate?
- What is the function of these products?
A
- Protein kinase S and C
- Regulate anticoagulation (inactivate factors 5a and 8a)
10
Q
- What form of Vitamin K is the active form?
- Where is it activated?
- What enzymes are responsible for its activation?
A
- Quinol
- Liver
- First converted from Vitamin K 2,3 epoxide to quinone form via vitamin k 2,3 epozide reductase (using NADH as a cofactor)
- Then converted from quinone form to quinol form via quinone reductase
11
Q
- How does Vitamin K activate factors II, VII, IV, and X?
A
- Involves the formation of gamma carboxyglutamate on factors II,VII, IV, and X
- This carboxyglutamate chelates Ca2+ in vivo
- Allows these factors to bind to phospholipid membranes during activation of the coagulation cascade
12
Q
- How does Warfarin inhibit the clotting cascade? (Remember that warfarin is an anticoagulant (don’t want clots forming))
A
- inhibits vitamin k 2,3 decarboxylase enzyme,
- As a result, vitamin K cannot be activated
- Factors II, VII, IX and X not activated
13
Q
- Warfarin is given as a racemic mixture. Which form is more active?
A
- Warfarin S
14
Q
- A deficiency in which factor is associated with Hemophilia A?
A
- Factor 8
15
Q
What is the function of thrombolytics?
A
- aid in the conversion of plasminogen to plasmin
- Cleave thrombin and fibrin formed clots
- So used to destroy already formed clots
- Used to treat ischemic stroke
- tPA and urokinase are examples
