Haemostasis

Question 1

What is haemostasis?

Answer 1

A precisely orchestrated series of regulatory process that culminate in the formation of a blood clot that limits bleeding from and injured vessel

Question 2

What does haemostasis allow?

Answer 2

Blood to be in a fluid state in normal vessels

Formation of localised haemostatic clot at sites of injury

Prevents haemorrhage

Question 3

List 3 causes of oedema

Answer 3

Heart failure

Liver failure

Kidney failure

Question 4

What are the 3 key components of haemostasis?

Answer 4

Vascular wall

Platelets

Coagulation cascade

Question 5

What are the 3 layers of a blood vessel?

Answer 5

Intima - endothelium, basement membrane, connective tissue, internal elastic lamina

Media - smooth muscle

Adventitia - connective tissue

Question 6

What cells are in the endothelium of the blood vessel?

Answer 6

Stratified simple squamous

Question 7

In what layer of the blood vessel is the vascular and neural supply?

Answer 7

Adventitia

Question 8

Normally endothelium cells are:

Answer 8

Antiplatelet

Anticoagulant

Fibrinolytic

Question 9

The role of platelets is to:

Answer 9

Provide the initial haemostatic plug

Provide a surface for recruitment and concentration of coagulation factors

Question 10

Name the three stages by which platelets carry out their 2 roles:

Answer 10

Adhesion to extracellular matrix at sites of vascular injury

Activation by secretion of granules

Aggregation of platelets

Question 11

What are the four stages of haemostasis?

Answer 11

Vasoconstriction

Primary haemostasis

Secondary haemostasis

Clot stabilisation and resorption

Question 12

What factor is released from the sub endothelium in primary haemostasis?

Answer 12

von Willebrand factor (vWF)

Question 13

What two things do platelets come in contact with in primary haemostasis?

Answer 13

Collagen

vWF

Question 14

Which cells secrete tissue factor?

Answer 14

Smooth muscle cells

Fibroblasts

Question 15

Which factor does TF bind to and activate?

Answer 15

Factor VII

Question 16

Which glycoprotein binds fibrinogen to platelets?

Answer 16

GP IIa/IIIb

Question 17

Which factors does Vit K synthesise?

Answer 17

VII, IX, X

Question 18

Where are most of the coagulation factors synthesised?

Answer 18

The liver

Question 19

Which glycoprotein binds vWF to exposed collagen?

Answer 19

GP Ib.

Question 20

Coagulation requires:

Answer 20

Coagulation factors

Cofactors

-ve charged phospholipid surface

Calcium ions

Vitamin K

Question 21

Which factors are dependent on vitamin K?

Answer 21

VII, IX, X, prothrombin

Question 22

What are the two cofactors of the clotting cascade?

Answer 22

V and VIII

Question 23

Which factors are involved in the clotting cascade?

Answer 23

Activated versions of XII, XI, IX, X, VIII

Question 24

Which factors does thrombi activate?

Answer 24

XI, VIII, V

Question 25

Which blood test measures the function of the extrinsic pathway?

Answer 25

PT blood test

Question 26

Which blood test measures the function of the intrinsic pathway?

Answer 26

apTT blood test

Question 27

What does thrombin do that amplifies the clotting response?

Answer 27

Activates factors XI, V and VIII Activates platelets (more -ve charged surfaces)

Question 28

What does heparin bind to? What does this enhance the inactivation of?

Answer 28

Antithrombin III Enhances inactivation of thrombin, IXa, Xa, XIa, XIIx

Question 29

What does unfractioned heparin enhance the inactivation of?

Answer 29

Xa and thrombin

Question 30

What does LMWH enhance the inactivation of?

Answer 30

Xa

Question 31

Warfarin effects the metabolism of

Answer 31

Vitamin K

Question 32

The fibrinolytic system

Answer 32

Plasminogen is activated to plasmin by tPA. Plasmin breaks down fibrin to fibrin degradation products (D-Dimer blood test)

Question 33

Which factors does warfarin inhibit the activation of?

Answer 33

Factors IX, VII, X, prothrombin

Question 34

Define haemorrhage

Answer 34

Extravasation of blood into the extravascular space (tissues, cavities, out of body)

Question 35

Factors affecting clinical significance of haemorrhage are:

Answer 35

Volume of blood lost Rate of blood loss Medical fitness Site of bleeding

Question 36

Define thrombosis

Answer 36

The pathological formation of a thrombus

Question 37

3 factors in Virchow's Triad

Answer 37

Endothelial injury Hypercoagulability Abnormal blood flow

Question 38

List the 4 fates of a thrombus

Answer 38

Propagation Embolisation Resolution/dissolution Organisation

Question 39

Define embolism

Answer 39

A detached intravascular solid, liquid, or gas that is carried by the blood to a site distant from its point of origin

Question 40

Define infarction

Answer 40

Area of ischaemic necrosis caused by inadequate blood supply