Hemostasis

Question 1

Describe the difference between primary and secondary hemostasis:

Answer 1

• Primary hemostasis = process by which a wound is initially plugged by platelets
• Secondary hemostasis = the process of fibrinogen binding platelets and becoming cross linked

Question 2

What is hemostasis?

Answer 2

-a process which causes bleeding to stop, keeping blood within a damaged vessel

Question 3

What is hemorrhage?

Answer 3

-bleeding, blood changing from a liquid to a solid state

Question 4

What are the major components that contribute to hemostasis?

Answer 4

• coagulation factors (I-XIII)
• Von Willebrand factor
• Platelets
• endothelial cells
• collagen

Question 5

What receptors on platelets bind to collagen in hemostasis?

Answer 5

-GPIa

Question 6

What binds to collagen if a wound is large, or if the flow is fast?

Answer 6

-Von Willebrand factor

Question 7

What binds to Vh factor?

Answer 7

-Platelets

Question 8

What does fibrinogen use to bind to platelets in hemostasis?

Answer 8

-GPIIb/IIIa

Question 9

What activates platelets in hemostasis?

Answer 9

-binding to collagen

Question 10

What is fibrinolysis?

Answer 10

• cleanup of the blood clot

- Tissue plasminoge activator (tPA) released by endothelial cells

Question 11

What converts plasminogen into plasmin?

Answer 11

-Tissue plasminogen activator along with Urokinase

Question 12

What does plasmin do?

Answer 12

-breaks up cross linked fibrin into fibrin degradation products (FDP) and fibrin split products (FSP)

Question 13

What are the two coagulation cascade pathways?

Answer 13

-Intrinsic & extrinsic

Question 14

What converts fibrinogen into fibrin?

Answer 14

-Thrombin

Question 15

What converts prothrombin into thrombin?

Answer 15

-Xa

Cofactors:

• Va
• Ca2+

Question 16

Where is most tissue factor located?

Answer 16

-on the monocyte and macrophage

Question 17

How many coagulation factors are there?

Answer 17

-12, no factor 6

Question 18

What converts fibrin into cross-linked fibrin?

Answer 18

-XIIIa

Question 19

What activates factor XIII?

Answer 19

-Thrombin

Question 20

Describe the prothrombin time (PT) test:

Answer 20

• Measures extrinsic pathway (injury pathway)
• measures clotting time of plasma after addition of thromboplastin (Tissue factor & phospholipids) and calcium
• end point is non-cross linked fibrin formation

Question 21

Describe the activated partial thromboplastin time (PTT) test:

Answer 21

• Measures intrinsic pathway
• Measures clotting time of plasma after addition of facter XII activator, phospholipid, & Ca2+
• end point is non-cross linked fibrin formation

Question 22

Describe the fibrinogen assay test:

Answer 22

• Measures fibrinogen activity

- Fibrinogen concentration is inversely proportional to thrombin time

Question 23

What is a necessary cofactor for gamma-carboxylation of prothrombin precursor?

Answer 23

-Vitamin K

Question 24

Which coagulation factors need vitamin k?

Answer 24

• II
• VII
• IX
• X

Question 25

What coagulation factor are deficient in hemophilia?

Answer 25

-8 and 9

Question 26

What are the three major steps of hemostasis?

Answer 26

1. Vasoconstriction 2. Temporary blockage of a break by a platelet plug 3. Blood Coagulation/formation of a fibrin clot

Question 27

How does heparin work?

Answer 27

- Anticoagulant - forms complex with antithrombin - inhibits thrombrin and Xa

Question 28

What is heparin monitored by?

Answer 28

-PTT

Question 29

How does warfarin/Coumadin work?

Answer 29

-Inhibits vitamin K synthesis

Question 30

What monitors warfarin?

Answer 30

-PT INR

Question 31

Is von willebrand factor involved in primary or secondary hemostasis?

Answer 31

Primary

Question 32

What is the end product of coagulation?

Answer 32

cross linked fibrin

Question 33

What are the three functions of von Willebrand factor?

Answer 33

1. Acts as bridge between platelets and collagen 2. Carrier protein for VIII 3.

Question 34

List the natural coagulation inhibitors:

Answer 34

- Protein C - Protein S - Antithrombin

Question 35

What activates Protein C?

Answer 35

-thrombin-thrombomodulin complex on endothelial cells

Question 36

What does protein C do?

Answer 36

-inactivates Va and VIIIa

Question 37

What is protein S?

Answer 37

-coenzyme for Protein C

Question 38

What does Antithrombin do?

Answer 38

-Inactivates Xa and Thrombin

Question 39

What accelerates the function of Antithrombin?

Answer 39

-Heparin

Question 40

Are platelets involved in primary or secondary hemostasis?

Answer 40

-Primary

Question 41

What are platelets derived from?

Answer 41

-cytoplasm of megakaryocytes

Question 42

What does thrombopoietin do? (TPO)

Answer 42

-Negative feedback regulation of platelet count

Question 43

Where is Thrombopoietin mainly produced?

Answer 43

-Liver

Question 44

What will decrease thrombopoietin?

Answer 44

-Increased platelet number

Question 45

What is thrombocytopenia?

Answer 45

-low platelet count

Question 46

What is thrombocytosis?

Answer 46

-high platelet count

Question 47

What are the 3 main causes of Thrombocytopenia?

Answer 47

- low platelet synthesis - destruction of platelets - sequestration of platelets

Question 48

What are the 4 main causes of Thrombocytosis?

Answer 48

-Reactive thrombocytosis

Question 49

What releases PDGF?

Answer 49

-Platelets

Question 50

What does PDGF do?

Answer 50

-grows smooth muscle cells to heal wounds

Question 51

What are the steps in platelet activation?

Answer 51

1. Adhesion 2. Shape change 3. Secretion 4. Aggregation

Question 52

What are the endothelial cell functions for hemostasis?

Answer 52

- Antithrombotic AND | - Prothrombotic

Question 53

What synthesizes von Willebrand factor?

Answer 53

- megakaryocytes | - endothelial cells

Question 54

What protects factor VIII?

Answer 54

-Von Willebrand factor

Question 55

What is a Weibel Palade body?

Answer 55

-Stores Von Willebrand factor in endothelial cells

Question 56

What is the first step in platelet function after an injury?

Answer 56

adhesion to collagen

Question 57

Why do we not test for factor XII in a prolonged intrinsic pathway result when bleeding is occuring?

Answer 57

- Factor XII deficiency will not cause bleeding | - deficiency is asymptomatic

Question 58

What is usual range for PT INR?

Answer 58

2.0-3.0

Question 59

What cofactor does protein C depend on?

Answer 59

Vitamnin K