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Question 1

What is mean cell volume?

Answer 1

Average volume of each red cell

Question 2

What is mean cell haemoglobin?

Answer 2

Average mass of Hb in each RBC

Question 3

What is mean cell haemoglobin concentration?

Answer 3

Average concentration of Hb in each RBC

Question 4

How is mean cell volume calculated?

Answer 4

Haematocrit/RBC in L

Question 5

How is mean cell haemoglobin calculated?

Answer 5

Hb/RBC in g

Question 6

How is mean cell haemoglobin concentration calculated?

Answer 6

Hb/Hct in g/L

Question 7

What is haematoxylin used to visualise?

Answer 7

Purple-blue component that binds to acidic components of cells. In particular it binds DNA and shows up the nucleus. Leishman’s stain also does this.

Question 8

What is eosin used to visualise?

Answer 8

pinkish stain that binds protein components, particularly in the cytoplasm.

Question 9

What 5 factors affect perfomance of light microscope?

Answer 9

1. Wavelength of light
2. Optical quality of lenses
3. Refractive index of medium that light passes through
4. Physical properties of the objective lens
5. Geometry of illuminating cone of light provided by condenser lens

Question 10

What are the 4 main fluid compartments of body and percentages of these?

Answer 10

Intracellular fluid 55%. Interstitial fluid 36%. Blood plasma 7%. Transcellular fluid (CSF, synovial fluid) 2%.

Question 11

What is apherisis?

Answer 11

Technique in which the blood of a donor is collected and passed through a centrifuge to separate a particular cellular component, with the remained returned to the donor.

Question 12

What can therapeutic apherisis be used for?

Answer 12

1. Plasma exchange - treatment if multiple sclerosis and myeloma.
2. Low Density Lipid Removal - treatment of patients prone to atherosclerosis
3. Red cell exchange - treatment of sickle cell disease
4. Platelet depletion - treatment of disorders of homeostasis
5. White blood cell depletion - treatment of leukaemia

Question 13

What are 6 functions of plasma?

Answer 13

1. Clotting
2. Immune defence
3. Osmotic pressure maintenance
4. Metabolism
5. Endocrine
6. Excretion

Question 14

How abundant is albumin and what are 2 main functions?

Answer 14

55% of total plasma protein is albumin and has several key functions including transport of lipids, hormones and ions + maintaining osmotic pressure of plasma.

Question 15

What is the role of alpha-1 globulins?

Answer 15

Alpha-1 antitrypsin is an example. Produced by liver and inhibits proteases such as neutrophil elastase. Defective or deficient A1AT can compromise the lung where degradation of lung tissue leads to a loss of elasticity and respiratory problems.

Question 16

What are the types of alpha-2 globulins and what do they do?

Answer 16

Haptoglobin and 𝛂2 -macroglobulin. Haptoglobulin binds to haemoglobin released from erythrocytes and the resulting haptoglobin-haemoglobin complex is removed by the spleen. Its levels help diagnose haemolytic anaemia. Alpha-2 macroglobulin is a protease inhibitor which stops fibrinolysis (clot breakdown).

Question 17

What are beta globulins?

Answer 17

Complement C3 and 4. Transferrin also.

Question 18

What are gamma globulins?

Answer 18

Immunoglobulins and C-reactive protein. Increase in these indicates increased immune activity.

Question 19

Why is the ABO blood group system important?

Answer 19

People have naturally occurring antibodies against any antigen NOT present on own red cells, from birth. Antibodies are IgM class, reactive at 37ºC and capable of fully activating complement, so are able to cause potentially fatal haemolysis

Question 20

Describe the blood types

Answer 20

A - anti-B antibodies in plasma and A antigens
B - anti-A antibodies in plasma and B antigens
O - anti-AB antibodies in plasma and no antigens
AB - no antibodies and A+B antigens

Question 21

How are the blood groups formed?

Answer 21

O only has the H-stem. A formed by the A gene which codes for an enzyme that adds N-acetyl galactosamine to the common H antigen. B formed by B gene which codes for enzyme which adds galactose. AB co-dominant, O is recessive.

Question 22

How is antigen D expression classified?

Answer 22

RhD indicates positive and Rhd is negative as d is recessive and D is dominant.

Question 23

What can Rhd negative people do?

Answer 23

Make anti-D antibodies AFTER they are exposed to the RhD antigen - either by transfusion of RhD positive blood, or in women if they are pregnant with an RhD positive foetus. Anti-D antibodies are IgG class antibodies.

Question 24

What are 2 complications of RhD mismatch?

Answer 24

1. Delayed haemolytic transfusion reaction - if they receive RhD positive blood, antibodies will react (anaemia, high bilirubin, jaundice)
2. Haemolytic disease of newborn - if RhD neg mother has anti-D, then in the next pregnancy, if fetus is RhD positive: mother’s IgG anti-D antibodies can cross the placenta, attach to red cells and cause haemolysis. If severe: hydrops fetalis. If less severe: high bilirubin after birth can cause brain damage

Question 25

What is an antibody screen?

Answer 25

Performed to exclude any clinically significant immune antibodies. Patient serum added to some screening red cells which have all clinically important antigens and if no reaction occurs, can go ahead. If screen is positive, antibody must be identified using large panel of red cells. Then donor blood lacking that antigen is selected for transfusion.

Question 26

What is compatibility testing?

Answer 26

First test patient serum for ABO group, RhD status and antibody screen. Then, cross-match to see if patient serum reacts with donor blood - if no agglutination, can transfuse.

Question 27

What is prion disease?

Answer 27

Prion proteins have been found in membranes of lymphocytes and platelets and the prions of variant Creutzfeldt-Jacob disease (CJD) are found in lymphoreticular tissues. No blood test available yet.

Question 28

What are the fractions of blood?

Answer 28

Red cells, Platelets and Plasma. Plasma can be FFP (Fresh, frozen plasma), Cryoprecipitate, Albumin.

Question 29

What are symptoms/signs of leukaemia?

Answer 29

1. fatigue, lethargy, pallor (anaemia) 2. fever and infections (neutropenia) 3. bruising and petechiae (thrombocytopenia) 4. bone pain (bone marrow expansion) 5. abdominal enlargement (hepatomegaly, splenomegaly) 6. lumps and swellings (lymphadenopathy)

Question 30

What do symptoms/signs results from?

Answer 30

Direct effects of proliferation like bone pain, enlarged spleen etc. Indirect effects are replacement of other normal bone marrow cells by leukaemic clone.

Question 31

What is flow cytometry?

Answer 31

Cytogenetic/molecular analysis of blood and bone marrow. FBC and blood film taken + cell surface markers found to determine whether its a T or B lymphocyte.

Question 32

What are 4 mechanisms of anaemia?

Answer 32

1. Reduced production 2. Loss of blood 3. Reduced survival time (haemolysis) 4. Pooling in the spleen

Question 33

What are 3 common causes of microcytosis?

Answer 33

Usually accompanied by hypochromia. 1. Iron deficiency 2. Anaemia of chronic disease 3. Thalassemia (reduced globin synthesis)

Question 34

What are 3 causes of iron deficiency?

Answer 34

1. Increased loss (hookworm, menstruation menorrhagia) - GI bleeds also possible 2. Increased requirement (myeloproliferative disorder, polycythaemia, pregnancy) 3. Insufficient intake (diet, malabsorption Coeliac disease)

Question 35

What are 3 stages of iron depletion?

Answer 35

Depletion: Storage iron absent/reduced Deficiency: low serum iron and transferrin saturation Anaemia: low haemoglobin and haematocrit

Question 36

What are 5 causes of anaemia of chronic disease?

Answer 36

``` Rheumatoid arthritis Autoimmune disease Malignancy Kidney disease Infections such as TB or HIV ```

Question 37

What are 5 diagnostic clues of anaemia of chronic disease?

Answer 37

C-reactive protein is high (unlike iron deficiency) Erythrocyte sedimentation rate (ESR) is high (unlike iron deficiency) Ferritin is high Transferrin is low Acute phase proteins increase

Question 38

What is normal number of red cells?

Answer 38

3.5 - 5 x 10^12 cells

Question 39

Where is haemoglobin synthesised?

Answer 39

Haem synthesised in mitochondria. Globin synthesised in ER.

Question 40

What are normal haemoglobin levels?

Answer 40

120-165g/L is normal concentration in adults. Each gram of Hb contains 3.4mg Fe.

Question 41

What are the diff haemoglobins separated based on during electrophoresis?

Answer 41

Based on charge.

Question 42

What conditions is electrophoresis carried out under?

Answer 42

Electrophoresis will be carried out on cellulose acetate gel strips, in a Tris-glycine buffer at pH 9.5. Under these conditions, the haemoglobin has an overall negative charge and will migrate towards the anode (positive electrode).

Question 43

How is oxygen removed from haemoglobin?

Answer 43

Sodium dithionite added

Question 44

What is Beer Lambert law?

Answer 44

The absorbance of a solution is proportional to the concentration of the absorbing material within it and to the distance (or path length) travelled by the light through the sample.

Question 45

What are spectrophotometry results for oxygenated and deoxygenated haemoglobin?

Answer 45

Oxygenated blood has 2 peaks at 540nm and 580nm. Deoxygenated blood has one at 560nm.

Question 46

What is carboxyhaemoglobin?

Answer 46

Carbon dioxide binding haemoglobin which has a greater affinity for CO compared to O2. CO outcompetes O2 so dangerous.

Question 47

What is methaemoglobin?

Answer 47

Generated when the Fe2+ ion is oxidised to the Fe3+ (ferric) state which results in greatly impaired oxygen binding. This gives the blood a bluish/chocolate colour. Causes left shift and anoxia as oxygen not released.

Question 48

Why is methaemoglobin not normally present?

Answer 48

The enzyme methemoglobin reductase reduces​ methaemoglobin back to ​haemoglobin. The disorder methaemaglobinaemia can be hereditary, for example as a deficiency in methemoglobin reductase or production of a mutant form of haemoglobin known as haemoglobin M, which is resistant to reduction.

Question 49

What causes methaemoglobin?

Answer 49

Acquired following exposure to chemicals including aniline dues such as p-chloroaniline, nitrates, and local anaesthetics such as benzocaine.