Haemostasis

Question 1

What cell components are involved when you form a clot?

Answer 1

1 - Platelets

2 - Von Willebrand Factor

3 - Coagulation factors

Question 2

Why blood clots not spread past the site of injury?

Answer 2

Natural anticoagulants

Question 3

What blood system is responsible for the blood clot vanishing 1 week after the injury?

Answer 3

Fibrinolytic system

Question 4

What sorts of things can cause platelets and coagulation factors to become activated to form a clot?

Answer 4

Abnormal vessel surface

Physiological activator

Question 5

Heparans and prostacyclin are both found within the endothelial surface of blood vessels to prevent what from happening?

Answer 5

Clotting

Question 6

How do platelets react to vessel damage?

Answer 6

They are attracted to the non-sticky surface of the sub-endothelium which has been exposed by the damage

The platelets stick to the collagen on the surface of the subendothelium

Question 7

What are the roles of platelets in haemostasis?

Answer 7

1 - Adhere

2 - Activation

3 - Aggregation

Question 8

What are the 3 major steps of haemostasis?

Answer 8

1 - Vasoconstriction

2 - Temporary blocakge by a platelet plug

3 - Coagulation

Question 9

What molecules are responsible for causing vasoconstriction following damage to a vessel?

Answer 9

Paracrines

Question 10

Once platelets have adhered to the collagen on the exposed sub-endothelium surface, what happens next?

Answer 10

Cytokines are released which reinforce vasoconstriction and attract more platelets which aggregate and form a platelet plug

Question 11

How does the formation of the blood clot begin?

Answer 11

Tissue factor attaches to collagen and sets off the coagulation cascade

Question 12

Once the coagulation cascade has been activated, what happens?

Answer 12

1 - Thrombin formation

2 - Thrombin converts fibrinogen to fibrin

3 - Fibrin reinforces the platelet plug already formed

Question 13

What is the final product of the coagulation cascade?

Answer 13

Fibrin

Question 14

How are blood clots dissolved once the tissue has been repaired?

Answer 14

Plasmin dissolves the fibrin in the blood clot

Question 15

What is the 1st enzyme activated in the coagulation cascade in the intrinsic pathway?

Answer 15

Factor XII

Question 16

What is the 1st enzyme activated in the coagulation cascade in the extrinsic pathway?

Answer 16

III (Tissue Factor)

Question 17

Tissue Factor activates which enzyme to begin the extrinsic coagulation cascade?

Answer 17

VII

Question 18

What is the common goal of the extrinsic and intrinsic pathways of the coagulation cascade?

Answer 18

To produce Thrombin

Question 19

What is the function of Thrombin?

Answer 19

Convert fibrinogen into fibrin

Question 20

What enzyme converts fibrin into a more stable version that stabilizes the clot?

Answer 20

XIII

Question 21

How is plasmin (breaks down fibrin) formed?

Answer 21

Thrombin + Tissue plasminogen activator

Question 22

What is a breakdown product of fibrin?

Answer 22

D-dimer

Question 23

What can D-dimer be used for?

Answer 23

Detection of:

DVT

Pulmonary Embolism

Question 24

What are the 2 mechanisms that prevent clots from growing indefinitely?

Answer 24

1 - Inhibition of platelet adhesion

2 - Inhibition of coagulation cascade & fibrin production

Question 25

What are the three anticoagulants produced by the body?

Answer 25

1 - TFPI 2 - Antithrombin III 3 - Protein C & S

Question 26

If clots have formed in the body due to diseases (e.g. MI's, DVT's, PE's), what are the medication options for dissolving the clots?

Answer 26

1) Fibrinolytic/Throbolytic drugs 2) Antiplatelets 3) Anticoagulants

Question 27

What are examples of thrombolytic drugs?

Answer 27

1) Streptokinase 2) Alteplase (tissue plasminogen activator)

Question 28

What are examples of anticoagulant drugs?

Answer 28

1) LMWH 2) Warfarin

Question 29

What are examples of antiplatelet drugs?

Answer 29

1) Aspirin 2) Clopidogrel 3) Ticagrelor

Question 30

What is the target of thrombolytic/fibrinolytic drugs?

Answer 30

Fibrin

Question 31

What is the action of aspirin?

Answer 31

Inhibits cyclooxygenase (COX)

Question 32

What is the action of clopidogrel and ticagrelor?

Answer 32

ADP receptor inhibitor

Question 33

What is the mechanism of action of warfarin?

Answer 33

Prevents prothrombin production by antagonising Vitamin K

Question 34

What is the mechanism of action of LMWH?

Answer 34

Binds to antithrombin making it more active Blocks Xa coagulation factor

Question 35

What are the 5 DOAC's most commonly used?

Answer 35

1 - Rivaroxaban 2 - Edoxaban 3 - Apixaban 4 - Dabigatran

Question 36

What are the 2 main actions of the DOAC's?

Answer 36

1 - Thrombin inhibition 2 - Factor Xa inhibition