Hemeonc 5

Question 1

What are the 5 steps of Hemostasis?

Answer 1

1. Formation of Platelet Plug
2. Propagation of Clotting process through coagulation cascade
3. Stabilization of Platelet Plug by Fibrin Formation
4. Termination of clotting through antithrombotic control mechanisms
5. Removal of clot by fibrinolyis

Question 2

Process of blood clot formation at the site of vessel injury

Answer 2

Hemostasis

Question 3

Who are the 3 key players in hemostasis?

Answer 3

1) Platelets
2) Plasma proteins (coagulation factors)
3) Vascular endothelium

Question 4

What are the 5 steps happen during the formation of the platelet plug?

Answer 4

1) Activation- Endothelial wall releases collagen and thrombin when injured to begin activation
2) Adhesion- deposition of activated platelets on the injured endothelium
3) Aggregation- platelet-platelet cohesion
4) Secretion- the release of platelet granules
5) Procoagulant activity- the enhancement of thrombin generation via coagulation cascade on PLT surface

Question 5

Which glycoprotein receptor is associated with Fibrinogen and is responsible for aggregation?

Answer 5

GP IIb/IIIa

Question 6

Which glycoprotein receptor is associated with von Willebrand factor and is responsible for adhesion to the epithelium?

Answer 6

GP Ib/V/IX

Question 7

What is the active enzyme that converts the plasma protein fibrinogen into an insoluble fibrin clot?

Answer 7

Thrombin

Question 8

Inactive enzyme precursor?

Answer 8

zymogen

Question 9

What is the purpose of the clotting cascade?

Answer 9

Activate the zymogens, create thrombin, use thrombin to create fibrin, reinforce platelet plug

Question 10

“Everybody wants to date a ten”. What does factor X do?

Answer 10

Clotting factor Xa converts the zymogen prothrombin to thrombin

Question 11

What pathway is initiated by the exposure of blood to a negatively charged surface (kaolin, silica). In vitro measured by partial thromboplastin time (PTT).?

Answer 11

Intrinsic pathway (XII, XI, IX, VIII)

Question 12

What pathway is activated by tissue factor exposed at the site of injury. In vitro measured by prothrombin time (PT).?

Answer 12

Extrinsic pathway (VII)

Question 13

Who are the 4 major players in anticoagulation?

Answer 13

1) Antithrombin III (amplified by Heparin x 1000)
2) Protein S
3) Protein C
4) Fibrinolytic system

Question 14

What does tPA (tissue plasminogen activator) do?

Answer 14

Turns Plasminogen into plasmin which breaks down fibrin clot

Question 15

So tPA is a “clot buster”, what inhibits tPA ?

Answer 15

antiplasmin, TAFI, PAI-1 (without these you’d have a bleeding disorder)