lecture 7 - coagulation

Question 1

What are the 3 pathways of the coagulation cascade?

Answer 1

Intrinsic, Extrinsic, Common

Question 2

What activates the intrinsic pathway of the coagulation cascade?

Answer 2

Collagen exposure (contact activation)

Question 3

What activates the extrinsic pathway of the coagulation cascade?

Answer 3

Tissue Factor (which binds to Factor VII)

Question 4

Which factors are involved in the intrinsic pathway of the coagulation cascade?

Answer 4

Factors XII, XI, IX, VIII

Question 5

Which factors are involved in the extrinsic pathway of the coagulation cascade?

Answer 5

Factor VII

Question 6

Which factors are involved in the common pathway of the coagulation cascade?

Answer 6

Factors X, Xa, V, II (prothrombin), I (fibrinogen)

Question 7

How do factors get activated in the coagulation cascade?

Answer 7

By cleavage (proteolytic reactions)

Question 8

What are the steps in the extrinsic pathway of the coagulation cascade?

Answer 8

1. Expression of tissue factor
2. TF binds to FVII, which is coverted to FVIIa
3. FVIIa activates FX to FXa
4. Common pathway…..

Question 9

What triggers the exposure of tissue factor?

Answer 9

Damage to blood vessel endothelium, resulting in exposure off underlying tissue factor lipoprotein

Question 10

What are the steps in the intrinsic pathway of the coagulation cascade?

Answer 10

1. Collagen fibres exposed
2. FVII binds to collagen
3. FVII activates FVI
4. FVI activates FIX,
5. FIX and FXIII activate FX
6. common pathway…

Question 11

How is the function of the extrinsic pathway measured in the laboratory?

Answer 11

Via Prothrombin Time or INR (international normalised ratio)

Question 12

What are the steps in the common pathway of the coagulation cascade?

Answer 12

1. FX activates to FXa with help of cofactor FV
2. FXa activates prothrombin (FII) to convert it thrombin
3. Thrombin activates fibrinogen to fibrin
4. Fibrin forms the clot

Question 13

Which pathway is factor VIII involved in in the coagulation cascade?

Answer 13

Intrinsic pathway

Question 14

What are the 2 key cofactors in the coagulation cascade?

Answer 14

Factor V, Factor VIII

Question 15

Where is FV involved in the coagulation cascade?

Answer 15

Common pathway - helps in conversion of prothrombin to thrombin

Question 16

What assist in the coagulation cascade, besides cofactors?

Answer 16

Ca2+, phospholipid, Vitamin k

Question 17

On what cells does the coagulation cascade often occur?

Answer 17

Platelets (on their phospholipid membranes)

Question 18

How is the function of the intrinsic pathway of the coagulation cascade measured in the laboratory?

Answer 18

Activated partial thromboplastin time (APTT)

Question 19

What is the function of FXIII in coagulation?

Answer 19

It crosslinks the fibrin to strengthen the clot

Question 20

What is the process of dissolving a blood clot?

Answer 20

Fibrinolysis

Question 21

What is the process of fibrinolysis?

Answer 21

Plasminogen in the clot is converted plasmin, which breaks down the fibrin and makes it soluble

Question 22

What degradation product of fibrinolysis can be measured in the laboratory?

Answer 22

D-dimers

Question 23

What are the 2 main sources of coagulation factors?

Answer 23

Liver (most factors), endothelium (von Wilebrand factor)

Question 24

Which factors and proteins rely on Vitamin K for post-translational modifications, and therefore activation and function?

Answer 24

‘1972’ - X, IX, VII, II (prothrombin)
Proteins C & S

Question 25

What is the most commonly used Vitamin K antagonist?

Answer 25

Warfarin

Question 26

What factors in the coagulation cascade does warfarin inhibit the activation of?

Answer 26

X, IX, VII, II

Question 27

What are the 3 main naturally and normally occurring inhibitors of blood coagulation?

Answer 27

Antithrombin, Protein C, Protein S

Question 28

What activates plasminogen to plasmin?

Answer 28

tPA (tissue plasminogen activator)