10.16.18 Hemostasis and Thrombosis

Question 1

What are the 2-fold mechanisms underlying the arrest of bleeding?

Answer 1

1. Vasoconstriction

2. Formation of hemostatic plug

Question 2

Arrest of bleeding following vascular injury

Answer 2

Hemostasis

Question 3

What type of interactions is hemostasis dependent upon?

Answer 3

1. Platelet adhesion/aggregation
2. Endothelial cell function
3. Blood coagulation system
4. Clot lysis (fibrnolysis)

Question 4

What are the aspect of normal vessels that suppress hemostasis

Answer 4

1. Prostacyclin
2. Heparan sulfate
3. Tissue factor pathway inhibitor
4. Nitric oxide
5. Thrombomodulin

Question 5

What are platelets formed from?

What does a normal platelet count lie between?

Answer 5

Cytoplasm of bone marrow megakaryocyte

150-450

Question 6

What is sequence of events leading to blood clotting?

Answer 6

1. Vasoconstriction
2. Platelet aggregation
3. Coagulation

Question 7

What are the consequences of uncontrolled hemostasis?

Answer 7

1. Bleeding (hemorrhage)

2. Thrombosis (venous or arterial)

Question 8

Interacts in a highly ordered sequence of specific plasma proteins that convert soluble fibrinogen to insoluble fibrin in order to stabilize the primary hemostatic plug

Answer 8

Blood Coagulation System

Question 9

What are the zymogens/active enzymes in secondary hemostasis?

Cofactors?

Non-protein cofactors?

Answer 9

2,7,9,10 (Vit K dep); 11,12, 13 (Vit K indep)

5,7, TF, vWF- Cofactors

Ca, PL surfaces (non-protein cofactors)

Question 10

What factor is activated by thrombin and cross-links/stabilizes fibrin?

Answer 10

Factor 13

Question 11

What are the key factors that start and control hemostasis?

Answer 11

Factor 7 and 8 (shortest half life/plasma amounts)

Question 12

What do activated platelets release to recruit more platelets and promote aggregation

Answer 12

Granule contents (ADP, TxA2)

Question 13

integrin receptor; adheres to fibrinogen, enhances aggregation and stabilizes thrombus

Answer 13

Platelet glycoprotein IIb/IIIa

Question 14

What is released by endothelial cells to inhibit further platelet aggregation?

Answer 14

Prostacyclin and nitric oxide

Question 15

What stage of hemostasis are platelets and blood coagulation proteins involved in?

Answer 15

Platelets- primary

BCP- secondary

Question 16

In what pathways is thrombin involved in?

Answer 16

Coagulation and anticoagulation

Question 17

What coagulation factor does the common pathway begin with and what protease activates it?

Answer 17

Factor 10 activated by F7a/TF

Question 18

How does thrombin form fibrin monomer?

Answer 18

Cleaves 2 small activation peptides from fibrinogen

Question 19

the degradation product of cross-linked fibrin; reflects ongoing activation of the hemostatic system

minimal levels in health individual

Answer 19

D-Dimer

Question 20

Elevated D-dimer is useful for using in which clinical interpretations?

Answer 20

1. Evaluation of thrombus formation
2. Ruling out DVT
3. Monitoring anticoagulative treatment
4. Disseminated intravascular coagulation (DIC)

Question 21

In what ways can you turn off clotting?

Answer 21

1. Tissue Factor Pathway inhibitor
2. Coagulation protease inhibitor
3. Protein C System
4. Fibrinolysis

Question 22

Stimulates activation of protein C by thrombin

Answer 22

Thrombomodulin