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Anatomy and Physiology > Haematology II- Haemostasis and Blood Groups > Flashcards

Haematology II- Haemostasis and Blood Groups Flashcards

1
Q

what are the 3 steps of the haemostatic response?

A
  1. vasoconstriction
  2. platelet adhesion and aggregation
    3.coagulation phase
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2
Q

what is the other name for platelet?

A

thrombocyte

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3
Q

why is there a continual need for production of platelets

A

they have no nucleus

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4
Q

do platelets contain granules

A

yes

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5
Q

what are the contents of granules in platelets

A

contain clotting factors and other elements for hemostasis e.g necessary to form platelet plug

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6
Q

what type of cytoplasm do platelets have

A

Megakaryocyte cytoplasm

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7
Q

what is platelet production controlled by?

A

no. of circulating platelets (negative feedback),
- thrombopoietin (TPO) release (increase platelet numbers)

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8
Q

1 megakaryocyte forms how many platelets?

A

4000

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9
Q

what is the normal lifespan of platelets?

A

7-10 days

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10
Q

what is the first stage of haemostasis when there is vessel injury and collagen exposure

A

platelet adhesion

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11
Q

platelet adhesion

A

adhesion- platelets stick to the area that is damaged which activates them

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12
Q

after platelet activation, what do platelets release?

A

granular contents to help platelet plug formation

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13
Q

which two hormones do platelets release during platelet activation

A

serotonin and thromboxane A2

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14
Q

role of serotonin and thromboxane A2 in platelet activation

A

enhances vasoconstriction limiting blood flow to the damaged area

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15
Q

what is the role of ADP in platelet activation

A

allows the platelet to change shape and swell allowing platelets to easily come in contact with other platelets

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16
Q

what is the next stage after platelet activation

A

platelet aggregation

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17
Q

during platelet aggregation what is formed

A

the primary haemostatic plug

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18
Q

primary haemostatic plug

A

layer of platelets that build up on top of each other across the damaged area

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19
Q

what does platelet activation result in which is important for blood coagulation

A

platelet phospholipid

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20
Q

what is the coagulation phase

A

-the endpoint
-the conversion of soluble plasma protein to the insoluble rigid polymer fibrin (fibrin clot)

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21
Q

are fibrin clots and platelet plugs reversible

A

fibrin clots are irreversible whereas platelet plugs are reversible (if you squeezed a cut it would be able to open and continue bleeding)

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22
Q

which pathway is the beginning of the coagulation phase

A

extrinsic pathway

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23
Q

Stage 1 of extrinsic pathway of coagulation

A

Tissue damage exposes collagen and releases tissue factor (initiating factor of coagulation)

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24
Q

stage 2 of coagulation (extrinsic pathway)

A

released tissue factor comes into contact with factor VII (clotting factor) to form tissue factor factor VIIa complex

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25
Q

stage 3 of extrinsic pathway (coagulation)

A

tissue factor factor VIIa complex binds with the next clotting factor (factor X) activating factor Xa

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26
Q

the importance of the extrinsic pathway

A

it is responsible for around 80-90% of the factor X that goes towards the production of the fibrin clot

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27
Q

what other clotting factor does the extrinsic pathway produce?

A

small amounts of factor IX and thrombin that feedback and activates other clotting factors including factor VIII (cofactor for factor IX) and in combination they activate factor X

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28
Q

1st stage of the intrinsic pathway of coagulation

A

factor XII which is in circulation is activated to FXIIa by other elements due to the damaged blood vessel

29
Q

2nd stage of the intrinsic pathway (coagulation)

A

FXIIa activates FXI which activates FIX and finally activates FXa

30
Q

common pathway of coagulation

A

both intrinsic and extrinsic pathway come together to activate factor X and create the prothrombinase complex

30
Q

role of prothrombinase

A

activates prothrombin to thrombin

30
Q

prothrombinase

A

consists of FXa and FVa as a cofactor

31
Q

importance of thrombin

A

important in the feedback process e.g activates cofactors (factor VIII and factor V) and also activates more platelets

32
Q

which ions are the most important for the clotting process

A

calcium and vitamin k

33
Q

what is vitamin K necessary for?

A

the production of certain clotting factors in the liver including prothrombin

34
Q

risk of calcium deficiency

A

impairs blood clotting and at risk of more bleeding

35
Q

what controls blood clotting

A

within the plasma, there are several natural anticoagulants

36
Q

what are the two anticoagulants in the plasma

A

antithrombin and heparin

37
Q

antithrombin

A

inhibits thrombin

38
Q

heparin

A

released by basophils and mast cells (co-factor that accelerates actions of antithrombin)

39
Q

fibrinolysis

A

the breakdown of the fibrin clot

40
Q

main enzyme involved in fibrinolysis

A

plasmin

41
Q

plasmin

A

breaks down the fibrin into fibrin degradation products into different sizes

42
Q

precursor of plasmin

A

plasminogen

43
Q

how are blood types determined

A

genetically

44
Q

what are blood groups

A

combination of surface antigens on red blood cell membrane

45
Q

which blood group systems have the most clinical significance

A

ABO and Rh(D)

46
Q

group A antibodies in plasma

A

anti-B

47
Q

group A antigens in red blood cells

A

A antigen

48
Q

group B antibodies in plasma

A

anti-A

49
Q

group B antigens in red blood cell

A

B antigen

50
Q

group AB antibodies in plasma

A

none

51
Q

group AB antigens in RBC

A

A and B antigens

52
Q

group O antibodies in plasma

A

anti-A and anti-B

53
Q

group O antigens in RBC

A

none

54
Q

role of antibodies in plasma

A

protect against the antigen that doesn’t exist on the RBC

55
Q

what occurs when antibodies come across opposing antigens on RBCs

A

antibodies will stick to the RBC (agglutination) and start to break down the rbc and block the blood vessels which will inevitably cause anaemia

56
Q

ABO: which are dominant, which are recessive

A

A and b are dominant
O gene is recessive

57
Q

what does the Rh blood group determine

A

whether a person’s blood is positive or negative (Rh + or Rh -)
-this is the presence or absence of the D antigen

58
Q

why will an Rh(-) individual not usually have anti Rh (D) antibodies

A

this requires sensitisation by exposure to the Rh (+) RBCs

59
Q

when might exposure to the Rh(+) RBCs occur

A

transfusion
pregnancy/ birth

60
Q

what percentage of the population are Rh positive and what are Rh negative

A

85% are Rh positive
15% are Rh negative

61
Q

is there a link between abo and rh

A

no

62
Q

how would haemolytic disease of a newborn occur?

A

if the mother had Rh- blood and the fetus has Rh+ blood

63
Q

describe the haemolytic disease of the new-born

A

during childbirth, haemorrhage of the placenta causes exposure of the mother’s blood and the foetus’s blood
-if the foetus were to have rh+ blood and the mother was to have rh- blood, mother’s immune system would start to produce antibodies to fight against the ‘foreign’ blood cells
-if this were to occur, these antibodies would cross the fetal tissue. bind to the baby’s rbc and destroy them putting the baby at risk of developmental issues, anaemia or it could be fatal

64
Q

what would happen if the mother were to get pregnant again

A

the mother would already have the antibodies against the fetal RBCs and this would cause hemolysis

65
Q

how is haemolytic disease of a new born prevented

A

the mother may be given anti-d to prevent an immune response to the babies blood cells

66
Q

which blood group is known as the universal donor

A

O- as the blood cells have no surface antigens therefore an immune response will not occur with any other blood group

67
Q

which blood group is known as the universal acceptor

A

Blood group AB as they conatin both A and B surface antigens on their RBCs therefore no antibodies against A or B

Anatomy and Physiology (10 decks)

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