Blood Clots

Question 1

What are the three steps in the formation of a blood clot?

Answer 1

1. Vessel constriction
2. Platelet plug
3. Coagulation cascade

Question 2

What factors are released in the vessel constriction phase?

Answer 2

Prostaglandin F 2alpha and thromoxane A2

Question 3

Thromboxane A2, prostaglandin F 2alpha, ADP, and serotonin are all released by ____________.

Answer 3

Activated platelets

Question 4

What is the affect of platelet aggregation on the integrin receptor?

Answer 4

Allows it to bind fibrinogen -> platelets then bind to cross-linked fibrinogen to form platelet plug

Question 5

Proteolytic cleavage of fibrinogen to form _________, followed by chemical cross-linking by ___________ produces a blood clot.

Answer 5

Fibrin; factor XIII

Question 6

What cleaves the fibrinogen into fibrin?

Answer 6

Thrombin

Question 7

What has to bind to factor VII in order to activate it?

Answer 7

Tissue factor (TF)

*Extrinsic pathway

Question 8

Why is tissue factor only exposed to blood during tissue damage?

Answer 8

It is in the basement membrane

Question 9

What is activated by the active TF-VIIa?

Answer 9

Factors IX and X

Question 10

_____________ is produced by the liver and will inhibit several coagulation enzymes including thrombin.

Answer 10

Antithrombin

Activity increases with heparin

Question 11

What factors are most inhibited by Protein C?

Answer 11

Factor V and factor VIII

Question 12

How is protein C activated?

Answer 12

When it binds to thrombin

Activity increases with presence of thrombomodulin and EPCRs

Question 13

______________ can reversible inhibit Factor X.

Answer 13

Tissue factor pathway inhibitor (TFPI)

Question 14

___________ prevents clots from growing and becoming problematic.

Answer 14

Fibrinolysis

Question 15

T/F: Plasminogen is turned to its active form, plasmin, in order to break down clots.

Answer 15

True

Question 16

T/F: Indirect thrombin inhibitors act on antithrombin.

Answer 16

True

Question 17

T/F: When using unfractionated heparin, it is especially important to dose correctly.

Answer 17

True

Question 18

___________ binds to AT, and increases its activity about 1000 fold.

Answer 18

Heparin

Question 19

What is the major adverse effect of heparin?

Answer 19

Bleeding

Question 20

T/F: Direct thrombin inhibitors act on antithrombin.

Answer 20

False

Question 21

______________ is a synthetic version of hirudin, a naturally occuring direct thrombin inhibitor found in leeches.

Answer 21

Bivalirudin

Question 22

T/F: Argatroban is a direct thrombin inhibitor.

Answer 22

True

Question 23

What is the WARF in warfarin?

Answer 23

Wisconsin Alumni Research Foundation

Question 24

What are most oral direct thrombin inhibitors derived from?

Answer 24

Coumarin

Question 25

Which drug (warfarin or heparin) will give an immediate effect?

Answer 25

Heparin

Question 26

How do oral direct thrombin inhibitors (coumarins) work?

Answer 26

They inhibit an enzyme which will cause the body to run out of vitamin K which is needed to activate thrombin

Question 27

What are the antidotes for overdoses on heparin or warfarin?

Answer 27

Hep - protamine sulfate | Warf - vitamin K

Question 28

What are three ways that platelet aggregation is blocked pharmaceutically?

Answer 28

1. Inhibition of thromboxane A2 synthesis (aspirin) 2. Block ADP receptors (plavix) 3. Block GPIIb/IIIa

Question 29

How are hereditary bleeding disorders often treated?

Answer 29

Replacement therapy

Question 30

What are some common types of medications that can cause an increased risk for bleeding when the patient is on warfarin?

Answer 30

Antibiotics, antifungals, antidepressants, anti-inflammatory agents, acetaminophen