10 Haematology III - Transfusions and platelets

Question 1

How many systems are there for classifying blood?

Answer 1

35

Question 2

What is the most clinically relevant blood categorisation system?

Answer 2

ABO

Rh(D)

Question 3

What are the different blood groups?

Answer 3

A
AB
B
O

Question 4

What determines your blood group?

Answer 4

Genetics

the antigens on your RBCS

Question 5

Which antigens do A blood people have?

Answer 5

A

Question 6

Which antigens do B blood people have?

Answer 6

B

Question 7

Which antigens do AB blood people have?

Answer 7

Both

Question 8

Which antigens do O blood people have?

Answer 8

neither

Question 9

Which antibodies do A people have?

Answer 9

Anti B

Question 10

Which antibodies do B people have?

Answer 10

Anti A

Question 11

Which antibodies do AB people have?

Answer 11

none

Question 12

Which antibodies do O people have?

Answer 12

anti a and anti b

Question 13

What happens if you are transfused the wrong tyoe of blood?

Answer 13

The anti whatever antibodies detect the RBCs as foreign cells and cause agglutination which then causes blood cells to be broken down (hemolysis) and arteries can be blocked
It can be fatal.

Question 14

What antigens do you have if you are Rh(D) positive? what proportion of the population?

Answer 14

D

85%

Question 15

What antigens do you have if you are Rh(D) negative? what proportion of the population?

Answer 15

Just your A or B ones

15%

Question 16

What antibodies do you have if you are Rh(D) positive?

Answer 16

none

Question 17

What antibodies do you have if you are Rh(D) negative?

Answer 17

none - unless you have been exposed to Rh- blood in the past in which cases you have anti Rh(D) -this is a problem in pregnant women with Rh+ babies because the blood can mix during child birth and in the second child this will cause her blood to attack her babies blood

Question 18

What are the elements of haemostasis?

Answer 18

• vasoconstriction
• platelet adhesion and aggregation
• clotting - coagulation phase

Question 19

What is the balance we need to strike in haemostasis

Answer 19

we need a balance between excessive bleeding and clotting (know when to break the clot down)

Question 20

platelet structure:

Answer 20

• 2-3 micrometers in diameter (size of smallest blood vessels)
• no nucleus
• lifespan 7-10 days
• oval
• very small
• contain granules

Question 21

what does the release of granules in platelets do?

Answer 21

allows agglutination and adhesion

Question 22

Where cells are platelets made from?

Answer 22

Megakaryocytes

Question 23

What is the production of platelets controlled by?

Answer 23

• no of. circulating platelets (-ve feedback)

- thrombopoietin release (increases number of platelets)

Question 24

What happens when a blood vessel gets damaged? (not waterfall)

Answer 24

• vasoconstriction
• platelets activated by exposed collagen fibres in damaged endothelium
• platelets aggregate and adhere to colagen fibres
• adhesion causes them to change shape and release granular contents
• release 5-HT (vasoconstrictor)
• release ADP (activates more platelets and causes them to release more granular contents)
• When the platelet membrane changes shape it develops pseudopodia and gets bigger so it can aggregate better with other platelets
• Also releases Platelet Factor 3 (coagulant) and thomboxane A2 which activates platelets more and causes vasoconstriction
• through all this you get the formation of the temporary platelet

Question 25

What happens in the coagulation phase of haemostasis?

Answer 25

-Soluble plasma protein fibrinogen is converted to insoluble rigid polymer fibrin

Question 26

What is used in forming the stable clot?

Answer 26

- fibrinogen --> fibrin - thrombin (enzyme) ^^ - clotting factor 13 stabilises fibrin

Question 27

What happens in clotting? extrinsic pathway /initiation phase

Answer 27

tissue damage --> tissue factor released into blood stream --> combines with factor VII (7) and activates it = tissue factor-factor VIIa complex (a means activated) this activates factor X --> Factor Xa (X=10) -happens within seconds

Question 28

Which process produces more Factor Xa? intrinsic or extrinsic?

Answer 28

Intrinsic (90% more even though its slower)

Question 29

What happens in clotting? intrinsic pathway

Answer 29

Clotting Factor VIIII gets involved - its cofactor VIII helps speed thing up and they activate Factor X

Question 30

What happens in clotting? common pathway

Answer 30

Prothrobinase (consists of FXa and Fva as a cofactor) activates prothrombin to form thrombin thrombin converts fibrinogen to fibrin

Question 31

What does thrombin do?

Answer 31

converts fibrinogen to fibrin

Question 32

What inorganic compounds do we need for clotting?

Answer 32

Ca2+ from diet | Vitamin K from leafy greens for production of clotting factors in liver including prothrombin

Question 33

how do we control clotting?

Answer 33

Anticoagulants: antithrombin - inhibits thrombin and factor X and VIIII Heparin - released by basophils and mast cells - speeds up the action of antithrombin

Question 34

How do we break down clots?

Answer 34

Fibrinolysis: -main enzyme is plasmin breaks it down into fragments into fibrin degradation products - these levels can be monitored to determine if a person is producing too many clots

Question 35

How do we determine if someone is producing too many clots?

Answer 35

the level of fibrin degradation products in their blood