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Flashcards in T Deck (30)
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1

2

Function of hemostasis

Limit blood loss

3

Define thrombosis

Formation of blood clot inside the vessel

4

Endothelium has a non-thrombogenic surface

If this is intact, it generates prostaglandin and nitric oxide which inhibits platelet aggregation

5

When endothelium is damaged, sub-endothelial collagen is exposed and platelets will adhere to this - this will activate the platelets

The platelets will begin to Aggregate

6

Platelets release agents which promote vasoconstriction and platelet aggergation

Then fibrin will form through enzymatic reaction, these get meshed within the platelet plug, which stops the flow

7

Haemostatic plug is dissolved by fibrinolytic system

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8

“Blood clot” slide

Shows EMG of RBC in fibrin mesh

9

Calcium is required for clotting

Calcium chelators can be used to prevent clotting

10

Thrombin acts on

Fibrinogen to form fibrin

11

Extrinsic factor = the Easy pathway

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12

Blood clotting disorders

Learn

13

Fibrinolytic system stops the clotting cascade overrunning

Plans in breaks down fibrin polymers

14

Venous thrombosis vs arterial thrombosis

Problem with venous thrombosis - can break off and enter pulmonary circulation

15

Anticoagulants are involved in vitro storage of blood, as well as in vivo

Heparin - is polyanionic (has lots of negative charges)

16

Calcium chelators and heparin are main anticoagulants in vitro

EDTA is a chelator

17

In vivo use of anticoagulants

Heparin - given intravenously Warfarin - given orally

18

Heparin binds to antithrombin 3

Heparin antithrombin 3 complex binds to various clotting factors, inhibiting clotting cascade

19

Low MW heparin works differently from heparin

Binds factor 10a

20

LMWH does not inactive thrombin, but Unfractionated heparin does

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21

Side effects of heparin

Allergic reactions Haemorrhage Heparin induced thrombocytopenia (reduced platelet level, therefore platelet plug less likely to form)

22

Main oral anticoagulant is Warfarin - a structural analogue of vitamin K

Blocks synthesis of coagulation factors in the liver

23

Vitamin K required for caboxylation of certain clotting factors

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24

S warfarin and R warfarin

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25

Warfarin ends up bound to plasma albumin, other drugs can displace warfarin from binding sites on albumin

Example is aspirin

26

NSAIDs and warfarin don’t mix

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27

New oral anticoagulants

5

28

Aspirin irreversibly inhibits COX enzymes

Acetylation

29

Clopidogrel

Blocks platelet ADP receptors

30

Abciximab - MAB

Only used once??