Coagulation

Question 1

Intact endothelium prevents clotting. How?

Answer 1

Healthy endothelium releases
Nitric oxide
Prostacyclin
Tissue plasminogen activator

Question 2

What does nitric oxide do?

Answer 2

Inhibits platelet activation

Question 3

What does prostacyclin do?

Answer 3

Vasodilation

Question 4

What does tissue plasminogen activator do?

Answer 4

Promotes fibrinolysis

Question 5

Vessel damage - beginning of blood clotting

Answer 5

Damage exposes subendothelial collagen.
Allows von willebrand factor - binds and recruit platelets
Tissue factor is also released

Question 6

2nd step - extrinsic pathway activation

Answer 6

Tissue factor binds factor VIIa
This complex activates factor X which changes to Xa

Question 7

3rd step - platelet activation triggers intrinsic pathway

Answer 7

Activated platelets
Release polyphosphate
Expose negatively charged phospholipids
These support activation of intrinsic pathway factors

Question 8

4th step - common pathway

Answer 8

Both pathways (intrinsic and common) generate factor Xa

Converts prothrombin to thrombin
Thrombin converts fibrinogen to fibrin
Fibrinogen stabilises platelet plug to create fibrin clot

Question 9

What is extrinsic pathway triggered by?

Answer 9

Tissue factor

Question 10

What is extrinsic pathway measured by?

Answer 10

Prothrombin time

Question 11

Intrinsic pathway is triggered by?

Answer 11

Activated platelets

Question 12

What is intrinsic pathway measured by?

Answer 12

Activated partial thromboplastin time

Question 13

What does the common pathway start at?

Answer 13

Factor Xa
Where classic and alternative pathway converge

Question 14

What test is used to measure conversion of fibrinogen to fibrin

Answer 14

Thrombin time

Question 15

What does prolonged Thrombin time indicate?

Answer 15

Low fibrinogen or abnormal fibrinogen

Question 16

how is thrombin time measured?

Answer 16

Thrombin is added directly to plasma

Question 17

How is fibrinogen activity measured?

Answer 17

Fibrinogen assay

Question 18

How is extrinsic pathway measured?

Answer 18

Prothrombin time

Question 19

What does prolonged prothrombin time indicate?

Answer 19

Deficiency in extrinsic factors (VII)
Or Common pathway

Question 20

How is prothrombin time measured?

Answer 20

Thromboplastin used. - contains tissue factor

Question 21

What is used for monitoring warfarin (vitamin K antagonist)?

Answer 21

International normalised ratio

Question 22

How is the intrinsic pathway measured?

Answer 22

Activated partial partial thromboplastin time

Question 23

What does activated partial thromboplastin time activate?

Answer 23

Factor XII

Question 24

What does prolonged Activated partial thromboplastin time indicate?

Answer 24

Deficiency in intrinsic factors

Question 25

Example of a coagulation disorder

Answer 25

Haemophilia A

Question 26

What does haemophilia A cause?

Answer 26

Factor VIII deficiency Results in impaired clotting and abnormal bleeding

Question 27

Haemophilia A type of condition

Answer 27

X linked genetic mutation

Question 28

What condition is APTT prolonged?

Answer 28

Haemophilia A

Question 29

Red blood cell structure

Answer 29

Biconcave discs No nucleus Flexible membrane Carry oxygen via haemoglobin

Question 30

What does Landsteiner law state

Answer 30

You make antibodies against antigens you dont have