Anti-coagulant Heparin fractionated (LMWH) Flashcards
Do anticoagulants act on primary or secondary haemostasis?
- secondary haemostasis
What is the purpose of the coagulation cascade?
1 - accentuate primary haemostasis
2 - convert fibrinogen into fibrin
3 - inhibit platelets activation in primary haemostasis
2 - convert fibrinogen into fibrin
- fibrinogen = factor 1
- fibrin = 1a
- fibrin are monomers that form crosslinks and a strong clot
The coagulation cascade has 3 parts, intrinsic, extrinsic and common pathways. How is the intrinsic pathway started?
1 - factor XII (12) comes into contacts with collagen or activated platelets
2 - factor X (10) binds with fibrin
3 - factor XII (12) binds von willebrand factor
4 - factor XII (12) binds inactive platelets
1 - factor XII (12) comes into contacts with collagen or activated platelets
- platelets are activated from primary haemostasis
Once the intrinsic pathway has begun by factor XII (12) binding with activated platelets or collagen, what then happens in the intrinsic pathway?
1 - factor XII (12) then becomes factor X (10)
2 - activated platelets activate factor XI
3 - factor XII (12) becomes factor XIIa (12a) and activates factor XI (11), then IX (9) and then X (10)
4 - collagen activates factor XI (11)
3 - factor XII (12) becomes factor XIIa (12a) and activates factor XI (11), then IX (9) and then X (10)
In the intrinsic pathway, which factor activates the common pathway?
1 - factor XIIa (12a)
2 - factor XIa (11a)
3 - factor IX (9)
4 - factor Xa (10a)
4 - factor Xa (10a)
- Xa (10a) then activates factor II (2) called thrombin
- factor II (2) called thrombin then activates factor I (1) which builds the fibrin mesh
Once the common pathway has been activates by factor Xa (10) it activates factor II (2 thrombin) which activates factor Ia (1a, called fibrin) which begins building fibrin. Which 4 other cofactors is factor IIa (2a thrombin) able to also activate?
1 - Ia (1a), IIIa (3a), IVa (4a) and V (5a)
2 - XIa (11a), IIIa (3a), IVa (4a) and VIIa (7a)
3 - IIIa (3a), IVa (4a), Va (5a) and XIIa (12a)
4 - Va (5a), VIIIa (8a), IXa (9a) and XIIIa (13a)
4 - Va (5a), VIIIa (8a), IXa (9a) and XIIIa (13a)
- Va (5a) acts as a cofactor for factor Xa (10a)
- VIIIa (8a) acts as a cofactor for factor IXa (9a)
- IXa (9a)
- XIIIa (13a) helps factor I (1a) called fibrin form crosslinks and a stronger clot
The extrinsic pathway is activated when factor VIIa (7a) binds with what on exposed tissue?
1 - von Willebrand factor
2 - tissue factor
3 - tissue plasminogen factor
4 - protein C
2 - tissue factor
- factor VIIa (7a) then activates the factor Xa (10a) and the common pathway
In secondary haemostasis, which factor is often referred to as the accelerator due to its multiple procoagulating functions?
1 - factor IIa (2a)
2 - factor Xa (10a)
3 - factor Va (5a)
4 - factor Ia (1a)
1 - factor IIa (2a)
- also referred to as thrombin
Thrombin (factor IIa (2a) is able to do lots of things involved in coagulation. It does all of the following EXCEpt which one?
1 - binds platelets activating them
2 - activates factor Va (5a)
3 - activates factor VIIIa (8a)
4 - converts fibrinogen (factor I (1) into fibrin (factor Ia (1a))
5 -converts factor XIII (13) into factor XIIIa (13a) that binds with Ca2+ cofactor forming cross bridges between fibrin mesh
6 - activates protein C and S
6 - activates protein C and S
- proteins S and C ensure clotting does not go into overdrive
Factor IIa (2a) also called thrombin is one of the key cofactors in secondary haemostasis. What is the bodies natural molecule that aims to modulate the activation of thrombin?
1 - protein S
2 - protein C
3 - antithrombin (factor IIIa (3a))
4 - factor Va (5a)
3 - antithrombin (factor IIIa (3a))
Factor IIa (2a) also called thrombin is one of the key cofactors in secondary haemostasis. Antithrombin (factor IIIa (3a)) is the bodies naturally produced modulator of thrombin. Which 2 key factors in the common pathway is antithrombin (factor IIIa (3a)) able to bind with and reduce coagulation?
1 - factors Va (5a) and Xa (10a)
2 - factors IIa (2a) and Xa (10a)
3 - factors XIIIa (8a) and Xa (10a)
4 - factors IIa (2a) and XIIIa (13a)
2 - factors IIa (2a) and Xa (10a)
- this essentially inhibits or reduces the activity of the common pathway
- factor Xa converts prothrombin into thrombin (factor IIa (2a))
- remember 2 = 7 = 9, 10, 11, 12
Which factors overall is anti-thrombin (IIIa (3a)) able to bind with and inhibit?
1 - factors 1, 2, 3, 4 and 5
2 - factors 2, 7, 9, 10, 11 and 12
3 - factors 1, 2, 7, 9 and 10
4 - factors 5, 7, 9, 11, 13
2 - factors 2, 7, 9, 10, 11 and 12
- remember 2 = 7 = 9, 10, 11, 12
In secondary coagulation the extrinsic pathway is started when damaged endothelial cells release factor III (tissue factor III) which binds with the active factor VIIa (7a) and Ca2+. This then forms the VIIa-TF complex on the smooth muscle of blood vessels. The VIIa-TF complex then cleaves what factor?
1 - factor II (2 or prothrombin)
2 - factor X forming Xa
3 - factor VIII (8)
4 - factor V (5)
2 - factor X forming Xa
Once factor Xa has become active due to the extrinsic pathway, what factor does Xa (10a) and Ca2+ bind with that will then go onto form the prothrombinase complex?
1 - factor II (2 or prothrombin)
2 - factor I (1)
3 - factor VIII (8)
4 - factor V (5)
4 - factor V (5)
Once the prothrombinase complex has been formed by active factors X (10) and V (5), what does this then cleave in the extrinsic pathway?
1 - factor II (2 or prothrombin)
2 - factor I (1)
3 - factor VIII (8)
4 - factor XII (12)
1 - factor II (2 or prothrombin)
- prothrombin becomes thrombin (IIa)