Intro to Haematology

Question 1

What are the 3 main types of blood cells?

Answer 1

White blood cells (leucocytes)

Red blood cells (erythrocytes)

Platelets

Question 2

The main role of red blood cells?

Answer 2

Transporting gases in the bloodstream (oxygen and carbon dioxide)

Question 3

The main role of white blood cells?

Answer 3

Fighting infection

Question 4

The main role of platelets?

Answer 4

Preventing bleeding i.e. formation of clots.

Question 5

What is haematopoiesis and where is a site of occurrance?

Answer 5

The term used for the production of blood cells.

Occurs mainly in the bone marrow

Question 6

The sites of haematopoiesis vary with age. True/false?

Answer 6

True

Question 7

What are the various sites of haematopoesis?

Answer 7

Embryo: yolk sac then liver then marrow, 3rd-7th month in spleen.

At birth: mostly bone marrow, liver and spleen when needed.

Adult: haematopoiesis restricted to skull, ribs, sternum, pelvis, proximal ends of femur (axial skeleton).

Question 8

What happens to the number of active sites for haematopoiesis in the bone marrow from birth to maturity?

Answer 8

The number of active sites in the bone marrow decreases but retain ability for haematopoesis.

Question 9

What is erythropoiesis?

Answer 9

The production of red blood cells.

Question 10

What are the phases of erythropoiesis?

Answer 10

Proerythroblast

Basophilic erythroblast (early)

Polychromatophilic erythroblast

Orthrochromic erythroblast

Reticulocyte

Mature RBC

Question 11

One pronormoblast will result in many mature erythrocytes. True/false?

Answer 11

True

Question 12

What is thrombopoeisis?

Answer 12

Platelet formation

Question 13

What are the 3 main types of granulocytes?

Answer 13

Neutrophils, eosinophils and basophils

Question 14

What granulocyte is found most commonly?

Answer 14

Neutrophils

Question 15

Why are the cells known as granulocytes?

Answer 15

They contain granules that are easily visible on a stained blood film.

The 3 types are named based on the pattern of uptake of stain.

Eosinophils - the granules take up eosin which is red and acidic.

Basophils - the granules take up basic (alkali) dyes which are densely blue.

Neutrophils - the granules are fine and a “neutral” mix of the two colours.

Question 16

Characteristics of neutrophils?

Answer 16

Segmented nucleus, neutral-staining granules.

Immediate defence cell - phagocytes, release granule contents (die in process).

Attract other cells

Increased by body stress - infection, trauma, infarction.

Question 17

Characteristics of eosinophils?

Answer 17

Usually bi-lobed, bright orange/red granules.

Fight parasitic infections

Involved in hypersensitivity, often elevated in patients with allergic conditions e.g. asthma.

Question 18

Characteristics of basophils?

Answer 18

Large deep purple granules obscuring nucleus.

Quite infrequent in circulation.

Granules contain histamine.

Role is unclear, involved in mediation of hypersensitivity reactions

Question 19

Features of monocytes?

Answer 19

Large single nucleus, faintly stained granules, often vacuoled.

Circulates for a week and enter tissues to become macrophages.

Phagocytose invadors - kill them, present antigen to lymphocytes.

Attract other cells

Much longer lived than neutrophils

Question 20

Features of lymphocytes?

Answer 20

Small with condensed nucleus and rim of cytoplasm, when activated they appear large with plentiful blue cystoplasm extending around neighbouring red cells.

Cognate infection response.

Question 21

What tests are used to recognise the more primitive precursors?

Answer 21

Immunophenotyping

Bioassays

Question 22

What is immunophenotyping?

Answer 22

An expression profile of proteins (antigens) on the surface of cells.

Question 23

What are bioassays?

Answer 23

Culture in vitro and show lineage of progeny in different growth conditions.

Question 24

In clinical practice, how is the haematopoietic system examined?

Answer 24

Look at the peripheral blood (full blood count and blood film)

Look at the bone marrow - posterior iliac crests are common sites for bone marrow aspiration and biopsy

Specialised tests i.e. immunophenotyping and genetic tests).

Look at other sites that are relevant to blood production e.g. splenomegaly, hepatomegaly, lymphadenopathy.