Haemostasis 2: Coagulation

Question 1

What are the three main steps in haemostasis?

Answer 1

• Vessel constriction
• Platelet activation and plug formation
• Coagulation cascade activation

Question 2

What is the role of fibrin in haemostasis?

Answer 2

Fibrin provides structural strength for the haemostatic plug and anchors the plug to adjacent tissues.

Question 3

What is the source of Factor I (Fibrinogen)?

Answer 3

Liver

Question 4

Which factors are vitamin K dependent?

Answer 4

• Factor II (Prothrombin)
• Factor VII
• Factor IX
• Factor X

Question 5

What test measures the extrinsic pathway of coagulation?

Answer 5

Prothrombin time (PT)

Question 6

What activates the intrinsic pathway in coagulation?

Answer 6

Contact activation by kaolin or silica

Question 7

Fill in the blank: The activated partial thromboplastin time (APTT) measures the _______ pathway.

Answer 7

intrinsic

Question 8

What are co-factors in coagulation?

Answer 8

Enzymatic proteins that enhance the activity of coagulation factors

Question 9

What is the main function of tissue factor in the extrinsic pathway?

Answer 9

Initiates coagulation after endothelial damage

Question 10

What is the approximate time for a fibrin clot to form in the extrinsic pathway?

Answer 10

10 seconds

Question 11

What is the role of tissue plasminogen activator (tPA) in fibrinolysis?

Answer 11

Activates plasminogen to plasmin, which degrades fibrin

Question 12

True or False: Antithrombin binds irreversibly to coagulation factors.

Answer 12

True

Question 13

What is the result of a deficiency in antithrombin, Protein C, or Protein S?

Answer 13

High rate of venous thrombosis

Question 14

What does the term ‘thrombolysis’ refer to?

Answer 14

Breakdown of fibrin clots

Question 15

What happens during the cleavage of fibrinogen?

Answer 15

Fibrinogen is converted into fibrin by the cleavage of fibrinopeptides A and B

Question 16

What is the function of Factor XIII in coagulation?

Answer 16

Cross-links fibrin to stabilize the clot

Question 17

What are fibrin degradation products (FDPs)?

Answer 17

Products formed from the breakdown of fibrin, such as D-dimers

Question 18

What is the significance of D-dimers in diagnostics?

Answer 18

They are measured to assess clot formation

Question 19

What is the role of calcium in the coagulation process?

Answer 19

Required for the activity of several coagulation factors

Question 20

Fill in the blank: Inhibitors are necessary to _______ coagulation.

Answer 20

stop

Question 21

What is the consequence of an imbalance in coagulation and inhibition?

Answer 21

Too little coagulation leads to bleeding; too much coagulation leads to thrombosis

Question 22

What is thrombin derived from?

Answer 22

Prothrombin

Prothrombin is also known as Factor II.

Question 23

What does fibrinogen convert into during coagulation?

Answer 23

Fibrin

Fibrinogen is converted to fibrin by thrombin.

Question 24

What is the INTRINSIC coagulation pathway activated by?

Answer 24

APTT pathway, kaolin or silica

Question 25

Which factor activates Prothrombin to thrombin?

Answer 25

Factor Xa

Question 26

Which factors are involved in the coagulation pathways?

Answer 26

* VII * IX * XI * XII

Question 27

What role do co-factors play in coagulation?

Answer 27

Enhance the activity of coagulation factors

Question 28

Which factors are considered cofactors?

Answer 28

* FV * FVIII

Question 29

What is required for the activity of coagulation factors?

Answer 29

Calcium and phospholipid membranes

Question 30

Where does coagulation occur?

Answer 30

On phospholipid membranes, especially on platelets

Question 31

What does the prothrombin time (PT) test measure?

Answer 31

Time taken for a fibrin clot to form when Ca++ and tissue factor are added to plasma

Question 32

What is the approximate PT duration?

Answer 32

10 seconds

Question 33

What is the activated partial thromboplastin time (APTT) test used for?

Answer 33

Measures intrinsic pathway activation by silica or kaolin

Question 34

What is the approximate APTT duration?

Answer 34

25 seconds

Question 35

What is the structural difference between fibrinogen and fibrin?

Answer 35

Fibrinogen has fibrinopeptides A and B that are cleaved to form fibrin

Question 36

What is essential for the strength of a fibrin clot?

Answer 36

Crosslinking of fibrin by FXIII

Question 37

What are D-dimers?

Answer 37

Degradation products of fibrin measured in diagnostics

Question 38

What are the sources of coagulation factors?

Answer 38

* Liver * Endothelium

Question 39

What is the effect of liver failure on coagulation?

Answer 39

Can result in major haemostatic problems

Question 40

What is required for the activation of several clotting factors?

Answer 40

Post-translational modification

Question 41

Which factors undergo post-translational modification?

Answer 41

* II * VII * IX * X

Question 42

What is the role of vitamin K in coagulation?

Answer 42

Required for g-carboxylation of glutamate residues in clotting factors

Question 43

What happens during warfarin therapy?

Answer 43

Interferes with g-carboxylation of Factors II, VII, IX, X

Question 44

What is the role of antithrombin in coagulation?

Answer 44

Inhibits factors such as thrombin and Factor Xa

Question 45

What are the three main inhibitors of blood coagulation?

Answer 45

* Antithrombin * Protein C * Protein S

Question 46

What is the consequence of inhibitor deficiencies?

Answer 46

High rate of venous thrombosis

Question 47

What is fibrinolysis?

Answer 47

Degradation of fibrin clots

Question 48

What activates plasminogen to plasmin?

Answer 48

Tissue plasminogen activator (tPA)

Question 49

What is the role of tPA in fibrinolysis?

Answer 49

Clears excess fibrin inside vessels

Question 50

What is the importance of timely tPA administration during a heart attack?

Answer 50

The quicker the better for treatment