Coagulation Cascade

Question 1

Coagulation Factors

Answer 1

Most are formed in the liver in precuror forms by vitamin-K dependent process

Question 2

What does the Vitamin-K process do?

Answer 2

• Attaches calcium-binding prosthetic groups on the amino terminal regions of these factors
• Introduction of an extra COOH group on the side chain of several glutamic acid residues
• Called gamma-carboxyglutamic acid

Question 3

Absence of Vitamin-K

Answer 3

• Factors 2,7,9,10 are incomplete, lacking the special calcium-binding gamma-carboxyglutamic acids and appear as nonfunctional factors
• Known as PIVKA (protein induced by vitamin K absence/antagonism)

Question 4

What factors are synthesized by the Liver?

Answer 4

1,2,5,7,9,10,11,12

Question 5

Four Stages in blood clotting

Answer 5

1. Generation of Prothrombin Activator
2. Conversion of Prothrombin to Thrombin
3. Conversion of Fibrinogen to Fibrin
4. Stabilization of Fibrin

Question 6

Stage 1 (Clotting)

Answer 6

Extrinsic and intrinsic pathways converge at the final point in stage I where factor X reacts with V to produce prothrombinase

Question 7

Stage 2 (Clotting)

Answer 7

Conversion of prothrombin (II) to thrombin by prothrombinase

Question 8

Stage 3 (Clotting)

Answer 8

Consists of the catalytic conversion of fibrinogen to fibrin by thrombin (enzyme)

Question 9

Stage 4 (Clotting)

Answer 9

Factor XIII acts to stabilize the unstable fibrin

Question 10

Factor I

Answer 10

Fibrinogen

Question 11

Factor II

Answer 11

Prothrombin

Question 12

Factor III

Answer 12

Tissue Thromboplastin

Question 13

Factor IV

Answer 13

Ionized Calcium

Question 14

Factor V

Answer 14

Labile Factor or proaccelerin

Question 15

Factor VII

Answer 15

Stable Factor or proconvertin

Question 16

Factor VIII

Answer 16

Antihemophilic factor

Question 17

Factor IX

Answer 17

Plasma Thromboplastin Component or the Christmas Factor

Question 18

Factor X

Answer 18

Stuart-Prower factor

Question 19

Factor XI

Answer 19

plasma thromboplastin antecedent

Question 20

Factor XII

Answer 20

Hageman factor

Question 21

Factor XIII

Answer 21

fibrin-stabilizing factor

Question 22

Describe the activation of the intrinsic coagulation pathway

Answer 22

1. Damage exposes basement membrane collagen
2. Exposed collagen causes activation of Factor XII
   a.) Factor XIIa initiates the intrinsic coagulation pathway
3. Exposed collagen binds von Willebrand factor (vWf)

Question 23

What is the function of vWf?

Answer 23

Stabilizes platelet binding to collagen via a platelet membrane receptor

Question 24

Describe the intrinsic pathway coagulation sequence

Answer 24

1. Factor XIIa converts Factor XI to factor Xia
2. Factor XIa converts Factor IX to factor IXa
3. Factor IXa converts factor VIII to Factor VIIIa
4. Factor VIIIa activates the common pathway by converting Factor X to Factor Xa

Question 25

Describe the extrinsic pathway coagulation sequence

Answer 25

1. Damaged tissue cells secrete Tumor Necrosis Factor (TNF)
2. TNF causes endothelial cells, vascular smooth muscle cells, and fibroblasts to externalize adhesion receptors
3. TF converts Factor VII to Factor VIIa
4. Factor VIIa converts Factor X to Factor Xa, activating the common pathway

Question 26

Describe the common pathway coagulation sequence

Answer 26

1. Factor Xa converts Prothrombin to thrombin
2. Thrombin converts Factor V to Factor Va, which assists in converting prothrombin to thrombin
3. Thrombin converts Fibrinogen to fibrin
4. Thrombin converts Factor XIII to Factor XIIIa