Coagulation Shizzle

Question 1

The coagulation process has both an __________ and ___________ pathway.

Answer 1

Intrinsic and Extrinsic

Question 2

The intrinsic pathway includes which factors?

Answer 2

Factors 12, 11, 9, and 8.

Question 3

The extrinsic pathway includes which factors?

Answer 3

Factors 3 and 7

Question 4

Both extrinsic and intrinsic coagulation pathways lead to what common factor?

Answer 4

Factor 10a

Question 5

After factor 10a a common coagulation pathway is followed. Briefly describe this pathway.

Answer 5

Factor 5 leads to the creation of factor 2 (prothrombin), then factor 2a (thrombin), then to factor 1 (fibrinogen), and then finally to factor 1a (fibrin).

Question 6

What are the four stages of hemostasis?

Answer 6

Vasoconstriction, platelet aggregation, coagulation, and dissolution.

Question 7

Describe the first stage (vasoconstriction) during hemostasis.

Answer 7

The first stage happens right after the blood vessel is damaged. This causes a reduction in nitric oxide and prostacyclin which normally maintains vasodilation, and releases serotonin which enhances local vasoconstriction leading to spasms that constrict the vessel to help limit blood loss.

Question 8

Describe the second stage (platelet aggregation) during hemostasis.

Answer 8

The second stage occurs when damage to a blood vessel exposes Vaughn Willebrand factors in collagen of connective tissue and causes the release of thromboxane A2. The Txa2 activates the platelets so they can recognize the collagen and stick to it was well as aggregating together thus forming a platelet plug. Serotonin and ADP are also associated with uniquely effecting platelet aggregation. ADP in particular activates glycoprotein 2b/3a and P2Y12 causing platelet aggregation and thrombus stabilization.

Question 9

Describe the third stage (coagulation) during hemostasis.

Answer 9

The third step (or coagulation) occurs as prothrombin activator (via factors 5 & 10a) turns prothrombin (factor 2) into thrombin (factor 2a). The thrombin in turn cuts up fibrinogen (factor 1) into fibrin (factor 1a). Fibrins are like thin protein fibres which form a mesh over the platelet plug to reinforce it and complete the clot. As the mesh hardens (through factor 13/13a) it also helps provides a framework for tissue repair.

Question 10

Describe the fourth stage (dissolution) of hemostasis.

Answer 10

The fourth and final stage, dissolution, involves reversing this whole clotting cascade to break down the clot for removal. This involves fibrinolysis which is breaking down of the previously described fibrin. This occurs when plasminogen converts to the enzyme plasmin which goes to work cutting up the fibrin.

Question 11

What is factor 10a?

Answer 11

It is the common factor of the intrinsic and extrinsic coagulation pathways. After factor 10a begins the common coagulation pathway.

Question 12

Name for factor 2?

Answer 12

prothrombin

Question 13

Name for factor 2a?

Answer 13

Thrombin

Question 14

Name for factor 1?

Answer 14

Fibrinogen

Question 15

Name for factor 1a?

Answer 15

Fibrin

Question 16

What is factor 5?

Answer 16

Just know that it is after factor 10a and denotes the beginning of the common coagulation pathway leading to 2, 2a, 1, and 1a.

Question 17

What is thromboxane A2 responsible for in the coagulation pathway?

Answer 17

Platelet aggregation. The Txa2 activates platelets so they may begin sticking to each other as well as to collagen in the wound to form a platelet plug.

Question 18

What activates glycoprotein 2b/3a and P2Y12 to cause platelet aggregation and thrombus stabilization?

Answer 18

ADP

Question 19

What is the MOA of Plavix (clopidogrel bisulfate)?

Answer 19

Inhibits the binding of ADP to its platelet receptor and so stops ADP-mediated activation of the glycoprotein 2b/3a complex. This inhibits platelet aggregation.

Question 20

What is the MOA of Lovenox (enoxaparin sodium)?

Answer 20

It is a low molecular weight heparin that accelerates formation of the thrombin-antithrombin III complex and so deactivates thrombin (factor 2a) to prevent the conversion of fibrinogen (factor 1) to fibrin (factor 1a). Essentially, it helps prevent clot formation.

Question 21

What is the MOA of TNKase (tenecteplase)?

Answer 21

It is a modified form of human tissue plasminogen activator (tPA) that binds to fibrin and converts plasminogen to plasmin. This fibrin specificity produces local fibrinolysis in the area of recent clot formation, with limited systemic proteolysis.

Question 22

What is the MOA of Brilinta (ticagrelor)?

Answer 22

Reduces platelet aggregation – Reversibly inhibits platelet P2Y12 ADP receptor to prevent signal transduction and platelet activation.

Question 23

What is the MOA of Cyklokapron (tranexamic acid)?

Answer 23

Inhibits the normal process of fibrin breakdown by preventing the formation of plasmin from plasminogen.