Hemostasis: Blood coagulation and fibrinolysis - Part 3

Question 1

What occurs, in general, in the fibrinolysis (tertiary) phase of hemostasis

Answer 1

Dissolution of the fibrin clot

Question 2

What protein is incorporated into the developing clot which later plays a major role in degradation of the fibrin clot?

Answer 2

Plasminogen (inacitve)

Question 3

What factors cause inactive plasminogen to become active plasmin (proteolytic)?

Answer 3

• Tissue plasminogen activator
• Urokinase
• Streptokinase

Question 4

What factors keep inactive plasminogen inhibited?

Answer 4

• Plasminogen activator Inhibitory 1 & 2

- Antiplasmin (inhibits Active plasmin)

Question 5

What is the role of active plasmin?

Answer 5

Breaks down fibrin clot into fibrin degradation products (FDP)

Question 6

______ and _____ levels are raised in patients with DVT. They are estimated in clinical practice to estimate the extent and rate of _____ and in follow up patients with thrombosis.

Answer 6

• Fibrin degradation products (FDP)
• D-dimer
• Firbinolysis

Question 7

What are D-dimer levels?

Answer 7

• An important fibrin degradation product

- Used in tests to estimate rate of fibrinolysis

Question 8

What is the secondary hemostatic plug?

Answer 8

Plug broken down by plasmin into Fibrin degradation products

Question 9

Chemical mediators such as ___ and ____ are released by healthy endothelium and prevent platelet aggregation.

Answer 9

• PGI2

- Nitric Oxide

Question 10

What is the role of PGI2 in regards to platelet aggregation?

Answer 10

PGI2 increases cAMP levels within platelets and inhibits platelet activation.
-It is a thromboxane antagonist

Question 11

Coagulation automatically initiates what?

Answer 11

Fibrinolysis

Question 12

What are some anti-coagulation factors?

Answer 12

• Antithrombin III

- Protein C and S (aslo require vitamin K for gamma-carboxylation)

Question 13

What is the role of Antithrombin III?

Answer 13

• Binds to and inhibits factor Xa and thrombin (IIa)

- Heparin acts by activating this factor and preventing coagulation.

Question 14

What does Heparin activated to prevent clotting?

Answer 14

Antithrombin III

Question 15

What are the roles of Protein C and S?

Answer 15

Act together to inactivate cofactors Va and VIIIa.

Question 16

How is Protein C, and anti-coagulant factor, activated?

Answer 16

By the binding of thrombomodulin to thrombin.

Question 17

What is the role of Protein S?

Answer 17

Cofactor for protein C

Question 18

What is the role of Asprin and other COX 1 inhibitors?

Answer 18

prevent the formation of thromboxane in platelets. Action of aspirin on platelets is permanent.

Question 19

What is the role of Heparin?

Answer 19

activates antithrombin III and inactivates thrombin

Question 20

What is the role of Warfarin (oral anticoagulant)

Answer 20

blocks epoxide reductasein liver and prevents the regeneration of the active form of Vitamin K. Inhibits the synthesis of the mature vitK dependent clotting factors

Question 21

What is the role of streptokinase?

Answer 21

thrombolytic agent; plasminogen activator; converts plasminogen to plasmin enabling the dissolution of clots.

Question 22

The bleeding time test is an indicator of what?

Answer 22

Platelet plug formation

Question 23

Prolonged bleeding time is an indicator of what?

Answer 23

• Low platelet count OR
• vWF deficiency OR
• Platelet receptor defects

Question 24

What does the clotting time test tell you?

Answer 24

Time taken for the formation of the stable fibrin

Question 25

Prolonged clotting time indicated defects in what?

Answer 25

Coagulation pathway

Question 26

The bleeding time test tells you what?

Answer 26

Test for the time taken from the initial injury to the formation of the platelet plug

Question 27

Specific defects of the intrinsic/extrinsic pathways are indicated by what?

Answer 27

Prothrombin time & Activated partial thromboplastin time (APTT/ PTT)

Question 28

The prothrombin tiime (PT) test is also known as what?

Answer 28

International normalized ratio

Question 29

Prothrombin time (PT) measures what?

Answer 29

Tests the extrinsic and the common coagulation pathways

Question 30

The Prothrombin Time (PT) test measures defects in what?

Answer 30

• Tissue factor
• Factor VII
• Factor V
• Factor X
• Prothrombin
• Firbinogen

Question 31

The partial thromboplastin time (APTT) tests what?

Answer 31

Intrinsic and common pathways

Question 32

The Partial Thromboplastin Time (APTT) test measures defects in what?

Answer 32

• Factor VIII
• Factor IX
• Factor XI
• Factor XII
• Factor V
• Factor X
• Prothrombin
• Firbinogen