Blood clotting cascade

Question 1

What are the two pathways of the blood clotting cascade?

Answer 1

Intrinsic pathway

Extrinsic pathway

Question 2

What activates the intrinsic pathway?

Answer 2

Damaged endothelial lining of blood vessel

factor 12 binds

Question 3

What activates the extrinsic pathway?

Answer 3

Membrane damage exposes tissue factor

tissue factor = factor 3

Question 4

What do both the intrinsic and extrinsic pathways lead to?

Answer 4

Activation of factor 10

Question 5

What does activated factor 10 do?

Answer 5

Cleaves prothrombin into thrombin

Question 6

What does thrombin do?

Answer 6

Cleaves fibrinogen into fibrin

Positively feedbacks on activation of factors in intrinsic pathway and common pathway

Question 7

What does fibrin do?

Answer 7

Forms cross-links with other fibrin molecules

to form a fibrin clot

Question 8

What is the structure of prothrombin?

Answer 8

Protease

Kringle domains

Gla domain

Question 9

What is the function of the kringle domains in prothrombin?

Answer 9

Keep prothrombin in inactive form

Question 10

What is a Gla residue?

Answer 10

Extra COOH groups attached to glutamate

Question 11

Which factors have Gla residues?

Answer 11

Factors

• 2
• 7
• 9
• 10

Question 12

Where in the body are Gla residues formed?

Answer 12

Liver

Question 13

What is required for the formation of Gla residues?

Answer 13

Vitamin K

Question 14

What is the function of Gla residues?

Answer 14

Target factor to the site of injury

Question 15

How do Gla residues target factors to site of injury?

Answer 15

Negatively charged COOH- residues are attracted to calcium ions at site of injury

Question 16

What is the purpose of Gla residues targeting factors to the site of injury?

Answer 16

So that blood clots form at the site of injury only

Question 17

What is the structure of fibrinogen?

Answer 17

Two sets of tripeptides
joined by disulphide bond in the middle

Globular domains at middle and exterior ends

Question 18

What is the structure of fibrin?

Answer 18

Central globular domain is fibrinogen is cleaved off to form fibrin

Question 19

How does fibrin come together to form fibrin clot?

Answer 19

Exterior globular domains interact with exposed centre of fibrin

Question 20

How is the blood blotting cascade stopped?

Answer 20

Clotting factors diluted by blood flow

Clotting factors removed by liver

Clotthing factors digested by proteases

Clotting factors are inhibited

Question 21

What is an example a protease that digests clotting factors?

Answer 21

Protein C

Question 22

How is protein C activated?

Answer 22

By thrombin

Question 23

What do defects in protein C cause?

Answer 23

Thrombotic disease

Question 24

What is an example of an inhibitor of clotting factors?

Answer 24

Antithrombin

Question 25

What enhances the activity of antithrombin?

Answer 25

Heparin

Question 26

What is fibrinolysis?

Answer 26

The digestion of the fibrin clot into fibrin fragments

Question 27

What digests the fibrin clot into fibrin fragments?

Answer 27

Plasmin

Question 28

What forms active plasmin?

Answer 28

Tissue plasminogen active (tPA)

Streptokinase

Question 29

What is the inactive form of plasmin?

Answer 29

Plasminogen