Substances Secreted by Platelets and Their Role in Hemostasis ROLE IN HEMOSTASIS SUBSTANCE SOURCE COMMENT

Question 1

Contact activation of intrinsic coagulation
pathway

Answer 1

High Molecular Weight
Kininogen (HMWK)

Question 2

Converted to fibrin for clot formation

Answer 2

Fibrinogen

Question 3

Cofactor in fibrin clot formation

Answer 3

Factor V

Question 4

Assists platelet adhesion to sub- endothelium to provide coagulation surface

Answer 4

vWF

Question 5

Promote platelet aggregation

Answer 5

ADP
Calcium
Platelet Factor 4
Thrombospondin

Question 6

Promote platelet aggregation;
Also inhibits heparin

Answer 6

Platelet Factor 4

Question 7

Promotes vasoconstriction at injury site

Answer 7

Serotonin
Thromboxane A2 precursors

Question 8

Promotes vasoconstriction at injury site;
promotes platelet release reaction

Answer 8

Thromboxane A2 precursors

Question 9

Promotes smooth muscle growth for vessel repair

Answer 9

Platelet-derived growth factor

Question 10

Chemotactic for fibroblasts to help in vessel repair, inhibits heparin

Answer 10

Beta- thromboglobulin

Question 11

Precursor to plasmin, which includes clot
lysis

Answer 11

Plasminogen

Question 12

Plasmin inhibitor, inhibits clot lysis

Answer 12

Alpha-2- antiplasmin

Question 13

Inhibits XIa and thus factor IX activation

Answer 13

Protease nexin II
Platelet inhibitor of factor IX (PIXI)

Question 14

Complement system inhibitor

Answer 14

C1 Esterase Inhibitor