haemostasis

Question 1

how do endothelial cells help to control blood fluidity and flow?

Answer 1

• control the size of blood vessels
• when intact: contributes to preventing clots
• when injured: promote local clotting on exposed basement membrane

Question 2

what is haemostasis?

Answer 2

a process which causes bleeding to stop

Question 3

what is the opposite of haemostasis?

Answer 3

haemorrhage

Question 4

what is the first stage of wound healing?

Answer 4

haemostasis

Question 5

what happens with the endothelium is injured?

Answer 5

it stops secreting inhibitors and instead secretes Von Willebrand Factor

Question 6

what are the 3 stages of forming the haemostatic plug?

Answer 6

• platelet adhesion
• platelet activation
• platelet aggregation

Question 7

what do platelets release?

Answer 7

vasoconstrictors and pro-thrombotic agents

Question 8

where are megakaryocytes found?

Answer 8

in the bone marrow

Question 9

what is a thrombocyte?

Answer 9

a platelet

Question 10

what is thrombocytopenia?

Answer 10

low platelet count in blood

Question 11

what is platelet activation?

Answer 11

exocytose + change shape + increase respiratory rate

Question 12

what is the process of platelet activation?

Answer 12

extracellular ADP –> activation of P2Y receptor –> cation flow

Question 13

what do platelets release during activation?

Answer 13

thromboxane A2 (TXA2)

Question 14

what is factor Xa?

Answer 14

the activated version of factor X

Question 15

what are factor V and factor VIII?

Answer 15

co-factors that allow enzymes to function

Question 16

what is plasma?

Answer 16

fluid portion of the blood

Question 17

what is serum?

Answer 17

fluid left after clotting

Question 18

what is thrombosis?

Answer 18

abnormal formation of a clot locally

Question 19

what is an embolism?

Answer 19

abnormal migration of clot

Question 20

what are the 2 coagulation cascades?

Answer 20

• extrinsic (tissue factor) pathway

- intrinsic (contact activation) pathway

Question 21

what are the 3 pathways to activate factor X to factor Xa?

Answer 21

• extrinsic Xase
• intrinsic Xase
• thrombin also activates it

Question 22

what is extrinsic Xase

Answer 22

tissue factor + factor VIIa

Question 23

what is intrinsic Xase?

Answer 23

factor VIIIa + factor IXa

Question 24

what are the 2 coagulation factors?

Answer 24

prothrombin group & thrombin group

Question 25

what is prothrombin group?

Answer 25

- factors II, VII, IX & X - they are enzymes - vitamin K needed for synthesis - require calcium ions for activation - stable

Question 26

what is thrombin group?

Answer 26

- factors I, V & VII - thrombin activates them - V & VIII are co-factors - factor I is fibrinogen

Question 27

when is thrombin group increased?

Answer 27

in inflammation, pregnancy & with oral contraceptives

Question 28

what is vitamin K?

Answer 28

- a class of related fat-soluble vitamins - is required to synthesise enzyme coagulation factors - essential for gamma-carboxylation of clotting enzymes

Question 29

what enzyme coagulation factors does vitamin K synthesise?

Answer 29

prothombin II, VII, IX and X

Question 30

what does plasmin do?

Answer 30

lyses fibrin

Question 31

what is protein C?

Answer 31

a coagulation inhibitor

Question 32

what is antithrombin III

Answer 32

peptide in blood made by liver that blocks activity of thrombin

Question 33

what does vitamin K deficiency lead to?

Answer 33

insufficient clotting

Question 34

what is vitamin K deficiency caused by?

Answer 34

GI disease or no fat absorption

Question 35

what prevents the recycling of vitamin K?

Answer 35

warfarin

Question 36

what is haemophilia A?

Answer 36

a clotting disorder that affects larger blood vessels, joints and muscles and causes wounds to bleed for days

Question 37

what is haemophilia A caused by?

Answer 37

lack of factor VIII

Question 38

what type of disease is haemophilia A?

Answer 38

X linked

Question 39

how do you treat haemophilia A & what are the issues with it?

Answer 39

inject purified factor VIII but it is rare and expensive

Question 40

what is christmas disease and what is it caused by?

Answer 40

haemophilia B and it is caused by a defect in factor IX

Question 41

describe the process of inflammation atherogenesis

Answer 41

- monocytes enter lesion - become macrophages: consume cholesterol esters - can become foam cells - can die and release their contents which attracts more monocytes, cytokines and chemo-attractants

Question 42

describe lipid atherogenesis

Answer 42

- LDL deposits lipids in lesions - cholesterol esters are oxidised making oxygen radicals - oxidised lipids are consumed by macrophages

Question 43

describe endothelium atherogenesis

Answer 43

- endothelium expresses chemoattractants - when endothelium is lost, collagen stimulates coagulation - when endothelial is lost, vessel cannot control its dilation

Question 44

what 3 types of drugs can be given to control blood clotting?

Answer 44

- anti-platelet agents - anti-coagulants - fibrinolytics

Question 45

when are anti-platelet agents used?

Answer 45

to block platelet activation and good for treating arteriole disease

Question 46

when are anti-coagulants used?

Answer 46

to block production or activity of clotting factors and used to treat venous disease

Question 47

when are fibrinolytics used?

Answer 47

to dissolve fibrin in arterial disease

Question 48

what is aspirin?

Answer 48

a cyclo-oxygenase (COX) inhibitor

Question 49

what does aspirin do?

Answer 49

- blocks formation of thromboxane A2 in platelets - lengthens bleeding time - does NOT increase coagulation time

Question 50

name 2 ADP receptor inhibitors

Answer 50

- prasugrel | - clopidogrel

Question 51

what conditions can anticoagulants be used for?

Answer 51

- deep vein thrombosis | - pulmonary embolism

Question 52

name 2 oral anti-coagulants

Answer 52

- dabigatran | - rivaroxaban

Question 53

what is warfarin?

Answer 53

- vitamin k antagonist - slow onset (days) - requires monitoring

Question 54

what do heparins do?

Answer 54

- inhibit coagulation by inhibiting factor Xa

Question 55

what are fibrinolytics?

Answer 55

- clot busting drugs | - tissue plasminogen activator

Question 56

name 2 fibrinolytics

Answer 56

- streptokinase | - urokinase