Coagulation cascade and Fibrinolysis

Question 1

What is tissue facotr?

Answer 1

Transmembrane protein

Question 2

Where is TF located?

Answer 2

Plasma membrane of adventitial fibroblasts

Question 3

Which blood clotting factor binds to TF?

Answer 3

VII

Question 4

What does the TF/VIIa complex activate?

Answer 4

Clotting factors IX and X by proteolysis

Question 5

What does the TF mechanism ensure?

Answer 5

Spatially constrained clotting at sites of vascular damage

Question 6

What does the initial thrombin lead to?

Answer 6

Amplification of thrombin generation by activating factor XI, co-factor VIII and V and platelets

Question 7

What is the enzymatic activity of Xa enhanced by?

Answer 7

Va

Question 8

What does the assembley of IXa/VIIIA/X require?

Answer 8

Binding to platelet membranes

Question 9

What is the fibrin clot dissolved by?

Answer 9

Plasmin

Question 10

What is clot formation balanced by?

Answer 10

Clot degradation

Question 11

What system balances clot formation and clot degradation?

Answer 11

Fibrinolytic system

Question 12

What proenzyme does plasma contain?

Answer 12

plasminogen

Question 13

What 2 things does plasminogen bind to?

Answer 13

Fibrin and to cell surfaces

Question 14

What do plasminogen activators convert plasminogen to?

Answer 14

Enzymatically active plasmin

Question 15

What is plasmin?

Answer 15

Serine protease that digests fibrinogen and fibrin thereby dissolving clot

Question 16

What do endothelial cells continuously release?

Answer 16

Tissue plasminogen activator (tPA)

Question 17

How is tPA activated?

Answer 17

Binding to fibrin clots

Question 18

What is tPA’s major substrate?

Answer 18

Plasminogen

Question 19

What does partial degradation of fibrin by plasmin expose?

Answer 19

Further tPA binding sites on fibrin and plasmin activates tPA slightly by proteolysis

Question 20

What does tPA binding to fibrin initiate?

Answer 20

Local activation of fibrinolysis

Question 21

What are plasminogen activator inhibitors?

Answer 21

Serine protease inhibitors that block function of tPA

Question 22

Define thrombosis.

Answer 22

Clot formation inside vessels

Question 23

Where does venous thrombosis occur?

Answer 23

Lower limbs

Question 24

How do thrombus fragments reach the heart?

Answer 24

Carried by bloodstream through right heart into pulmonary arteries

Question 25

What do thrombus fragments cause?

Answer 25

Occlude blood flow through the lung leading to immediate sudden death

Question 26

What do arterial thrombosis lead to?

Answer 26

Local tissue damage depending on artery/organ