Haemostasis

Question 1

what is haemostasis?

Answer 1

the arrest of bleeding and the maintenance of vascular patency

Question 2

what is primary haemostasis?

Answer 2

formation of a platelet plug

Question 3

what is secondary haemostasis?

Answer 3

formation of the fibrin clot

Question 4

when does fibrinolysis occur?

Answer 4

when haemostasis is secure

Question 5

where are platelets formed and how?

Answer 5

bone marrow

budding off from megakaryocytes

Question 6

what is the average life span of a platelet?

Answer 6

7-10 days

Question 7

what do platelets bind to in damaged endothelium?

Answer 7

collagen

Question 8

what is a reduced number of platelets called?

Answer 8

thrombocytopenia

Question 9

what is a common cause of reduced platelet function?

Answer 9

taking anti-platelet medications

Question 10

how can problems with primary haemostasis present?

Answer 10

spontaneous bruising
mucosal bleeding
retinal haemorrhages

Question 11

what is the screening test to assess primary haemostasis?

Answer 11

platelet count - part of a FBC

Question 12

what does TF/VIIa do?

Answer 12

activates V/XA

Question 13

what does V/Xa do?

Answer 13

converts prothrombin to thrombin

Question 14

what does thrombin do?

Answer 14

converts fibrinogen to fibrin

activates VIII/IXa

Question 15

what does VIII/IXa do?

Answer 15

activates V/Xa

Question 16

what are the two possible groups of causes of a problem with secondary haemostasis?

Answer 16

single clotting factor deficiencies

multiple clotting factor deficiencies

Question 17

name a cause of a single clotting factor deficiency

Answer 17

haemophilia

Question 18

what clotting factor is deficient in haemophilia A?

Answer 18

VIII

Question 19

what clotting factor is deficient in haemophilia B?

Answer 19

IX

Question 20

name a potential cause of a multiple clotting factor deficiency

Answer 20

DIC

Question 21

what is fibrinolysis?

Answer 21

the breakdown of the fibrin clot

Question 22

what breaks down fibrin?

Answer 22

plasmin

Question 23

what is the plasmin precursor?

Answer 23

plasminogen

Question 24

what converts plasminogen to plasmin?

Answer 24

tissue plasminogen activator (TPA)

Question 25

what is the breakdown product of fibrin?

Answer 25

fibrin degradation products (FDPs)

Question 26

what are cross-linked FDPs called?

Answer 26

D-dimers

Question 27

what are the two screening tests for secondary haemostasis?

Answer 27

``` prothrombin time (PT) activated partial thromboplastin time (APTT) ```

Question 28

what test measures the intrinsic pathway in secondary haemostasis?

Answer 28

PT

Question 29

what test measures the extrinsic pathway in secondary haemostasis?

Answer 29

APTT

Question 30

name three naturally occurring anticoagulants

Answer 30

anti thrombin protein C protein S

Question 31

what is thrombophilia?

Answer 31

a deficiency of naturally occurring anticoagulants

Question 32

what does thrombophilia increase the risk of?

Answer 32

venous thrombosis

Question 33

what is the role of VWF?

Answer 33

helps hold platelets to each other and to collagen

Question 34

what clotting factor may be deficient if there is an isolated prolonged PT?

Answer 34

factor VII

Question 35

what coagulation screen result should be monitored when on warfarin?

Answer 35

INR - based on PT

Question 36

what coagulation screen result should be observed when on heparin?

Answer 36

APTT