Coagulation

Question 1

What are the 3 aspects of platelet role in coagulation?

Answer 1

Adherence
Activation
Agglutination

Question 2

What is the process of platelet adherence?

Answer 2

vWF binds to Gp1b on platelet surface

vWF binds to exposed collagen

Platelet adheres

Question 3

What does platelet adhesion cause?

Answer 3

Expression of GpIIb on platelet surface

Question 4

What is platelet activation?

Answer 4

ADP binds to platelet and causes expression of GpIIb

Question 5

What is platelet agglutination?

Answer 5

vWF binds to GpIIb and allows other platelets to bind to the first platelet

Question 6

What factors are promoted by thrombin?

Answer 6

V -> Va
VIII -> VIIIa
XI -> XIa
XIII -> XIIIa

Also activates thrombomodulin

Question 7

What does thrombomodulin do?

Answer 7

Reacts with protein C and protein S to produce activated protein C

Question 8

What is inhibited by protein C?

Answer 8

V -> Va

VIII -> VIIIa

Question 9

What pathway does TFPI inhibit?

Answer 9

Extrinsic

Stops VII -> VIIa

Question 10

What does antithrombin inhibit?

Answer 10

Directly inhibits thrombin by stopping activation of prothrombin

Question 11

What effect does warfarin have on PTT, aPTT, Bleeding time and platelet count?

Answer 11

PTT - increased
aPTT - normal
Bleeding time - normal
Platelet count - normal

Question 12

What effect does aspirin have on PTT, aPTT, Bleeding time and platelet count?

Answer 12

PTT - normal
aPTT - normal
Bleeding time - prolonged
Platelet count normal

Question 13

What effect does heparin have on PTT, aPTT, Bleeding time and platelet count?

Answer 13

PTT - can be raised
aPTT - prolonged
Bleeding time - normal
Platelet count normal

Question 14

What effect does DIC have on PTT, aPTT, Bleeding time and platelet count?

Answer 14

All prolonged

Platelet count low

Question 15

What effect does vWF disease have on PTT, aPTT, Bleeding time and platelet count?

Answer 15

All prolonged

Normal platelet count