Haemostasis

Question 1

What stops the bleeding when cut?

Answer 1

Platelets, vWf and coagulation factors

Question 2

What causes activation of platelets and coagulation factors?

Answer 2

Abnormal surface and physiological activator

Question 3

What does vessel damage cause?

Answer 3

Platelet adhesion
Von Willebrand factor and subendothelial collagen

Question 4

What binds fibrinogen?

Answer 4

GP IIb/IIIa binds fibrinogen
GP Ib binds to Von Willebrand factor

Question 5

What receptor binds to collagen?

Answer 5

GP Ia/IIa and GP VI

Question 6

What is the role of platelets in haemostasis?

Answer 6

Adhere, activation and aggregation
Provide phospholipid surface for coagulation

Question 7

What does vWF binding to GP Ib activate?

Answer 7

COX to turn arachnoid acid to thromboxane A2

Question 8

What causes aggregation?

Answer 8

Thromboxane A2

Question 9

What causes coagulation?

Answer 9

Phospholipid membrane and scramblase

Question 10

What is definitive haemostasis?

Answer 10

Fibrin formation

Question 11

What are the platelet glycoproteins?

Answer 11

GP IIb/IIa, Ib/V/IX, Ia/IIa and VI

Question 12

What are the cell surface receptors on platelets?

Answer 12

ADP receptor
Epinephrine receptor
Thrombin receptor

Question 13

What is in alpha granules and dense granules?

Answer 13

Alpha - VWF and thrombin
Dense - ADP/ ATP, calcium and serotonin

Question 14

What does ADP and epinephrine do when binding to platelet?

Answer 14

Help activate arachidonic acid as part of COX pathway

Question 15

What are some clotting agents?

Answer 15

Factor XII, XI, IX, VIII, X, prothrombin and fibrinogen
In order of activated

Question 16

What is haemophilia A and B?

Answer 16

A - factor VIII is deficient
B - factor IX is deficient

Question 17

Describe the extrinsic factor pathway

Answer 17

VII and tissue factor - activated factor X which completes the pathway to turn prothrombin to thrombin and fibrinogen to fibrin

Question 18

Describe the intrinsic coagulation cascade pathway

Answer 18

Factor XI activates factor IX which binds to VIII and can activate X to complete final part of pathway

Question 19

What are natural anticoagulants?

Answer 19

Activated protein C and protein S
TFPI - tissue factor pathway inhibitor and inhibits Xa

Question 20

What is the role of activated protein C?

Answer 20

Inactivates Va and VIIIa

Question 21

What is the role of antithrombin?

Answer 21

Inhibits thrombin and inactivates XIa, IXa and Xa

Question 22

Describe fibrinolysis

Answer 22

Plasminogen cleaved to plasmin by t-PA and u-PA
Plasmin breaks fibrin into fibrin degradation products

Question 23

How is plasminogen and plasmin inhibited?

Answer 23

Plasminogen - PA1 and PA2
Plasmin - alpha2-antiplasmin and alpha2-macroglobulin

Question 24

What is the role of aspirin?

Answer 24

Inhibits COX do stops conversion of arachidonic acid to thromboxane A2

Question 25

What is the role of clopidogrel, prasugrel and ticagrelor?

Answer 25

ATP inhibitors

Question 26

What is the mechanism of abciximab, tirofiban and eptifibatide?

Answer 26

Inhibit GP IIb/ IIIa

Question 27

What is the mechanism of warfarin?

Answer 27

Vitamin K antagonist Inhibits vitamin K dependant clotting factors - factor II, VII, IX and X

Question 28

What is the mechanism of herparins?

Answer 28

Inhibit antithrombin so inhibit Xa and thrombin

Question 29

What is the mechanism of DOACs?

Answer 29

Inhibit Xa

Question 30

What is the mechanism of dabigatran?

Answer 30

Inhibits thrombin