Coagulation: Basics

Question 1

what are the main steps of primary hemostasis?

Answer 1

• initial vessel spasm
• platelet aggregation
• fibrin formation
• initiation phase of cell model

Question 2

how long does primary hemostasis take?

Answer 2

seconds

Question 3

what does primary hemostasis culminate in?

Answer 3

platelet plug

Question 4

what are the main steps of secondary hemostasis?

Answer 4

• process of clot formation
• protease cascades of the clotting factors
• amplification and propagation phase of the cell model
• intrinsic and common pathways

Question 5

what does secondary hemostasis culminate in?

Answer 5

fibrin clot formation

Question 6

how long does secondary hemostasis take?

Answer 6

several minutes

Question 7

what is “Initiation”?

Answer 7

the initiation of hemostasis, when TF and VII (extrinsic pathway) –> produce small amounts of thrombin –> thrombin then activates platelets

Question 8

what factors start “Initiation”?

Answer 8

TF and VIIa

Question 9

What are the 3 major steps of platelet plug formation?

Answer 9

• adhesion
• aggregation
• activation

Question 10

what initiates platelet plug formation?

Answer 10

exposure of platelets to TF and basal lamina components like collagen

Question 11

what is “Adhesion”?

Answer 11

platelet adhesion to the surface collagen via VWF as well as directly

Question 12

what is “Aggregation”?

Answer 12

platelet to platelet attachment, mediated by fibrin and VWF

Question 13

what is “Activation” of platelets?

Answer 13

• degranulation –> releases vasoactive and platelet-activating mediators
• shape change –> from discs to flattened star shaped with cellular projections
• phosphatidylserine exposure on platelet surface –> essential for clotting factor binding

Question 14

what does “Amplification” mean?

Answer 14

• thrombin and other platelet granule content activates the intrinsic pathway –> thrombin burst
• activated platelet’s surfaces act as site for attachment for VIII and V

Question 15

what is propagation

Answer 15

activation of large amounts of thrombin –> “thrombin burst” –> large amounts of fibrinogen becoming fibrin

Question 16

what are the two common models of hemostasis?

Answer 16

• cascade model with extrinsic/intrinsic/common pathways

- cell model with primary and secondary hemostasis

Question 17

name factor I and Ia

Answer 17

fibrinogen and fibrin

Question 18

name factor II and IIa

Answer 18

prothrombin and thrombin

Question 19

name factor III

Answer 19

thromboplastin

Question 20

name factor IV

Answer 20

iCa

Question 21

name factor V

Answer 21

proaccelerin

Question 22

name factor VII

Answer 22

proconvertin

Question 23

name factor VIII

Answer 23

antihemophilic factor

Question 24

name factor IX

Answer 24

plasma thromboplastin component

Question 25

name factor X

Answer 25

Stuart-Prower factor

Question 26

name factor XI

Answer 26

plasma thromboplastin antecendent

Question 27

name factor XII

Answer 27

Hageman’s factor

Question 28

which factors require Vit K for synthesis

Answer 28

factors II, VII, IX, and X

Question 29

what factor can be synthesized outside the liver

Answer 29

factor VIII, but also mainly synthesized in the liver, also produced by endothelial cells

Question 30

what factor is required in the largest quantities for coagulation

Answer 30

fibrinogen (around 2-4 g/L in blood is normal)

Question 31

under what level does hypofibrinogenemia affect coagulation

Answer 31

levels below < 1.0 g/L