Haemopoiesis

Question 1

What cell types are included in granulocytes?

Answer 1

Neutrophils, eosinophils and basophils

Question 2

What do neutrophils do?

Answer 2

Phagocytosis/acute inflammation

Question 3

What do eosinophils do?

Answer 3

• Destroy parasites
• Modulate hypersensitivity reactions

Question 4

What do basophils do?

Answer 4

Not sure of function but they have a role in modulating hypersensitivity reactions

Question 5

What do red cells do?

Answer 5

Transport oxygen and carbon dioxide

Question 6

What do platelets do?

Answer 6

Primary Haemostasis

Question 7

What is another name for monocytes and what do they do?

Answer 7

Macrophages - modulate immune reactions, phagocytise clearance, regulatory functions

Question 8

What are the different types of lymphocytes and what are their functions?

Answer 8

• B cells - humoral immunity
• T cells - cell-mediated immunity, regulatory functions
• Natural killer cells - anti-viral/tumour

Question 9

What is myelopoiesis?

Answer 9

Production of granulocytes i.e. non-lymphoid WBCs

Question 10

What is the lifespan of red cells?

Answer 10

120 days

Question 11

What is the lifespan of neutrophils?

Answer 11

7-8 hours

Question 12

What is the lifespan of platelets?

Answer 12

7-10 days

Question 13

What is a blast?

Answer 13

A nucleated precursor cell e.g. myeloblast, erythroblast

Question 14

What is a megakaryocyte?

Answer 14

Platelet precursor, polyploid

Question 15

What is a reticulocyte?

Answer 15

Immediate red cell precursor - polychromasia

Question 16

What are myelocytes?

Answer 16

Nucleated precursor between neutrophils and blasts

Question 17

Where do all haemopoietic cells come from?

Answer 17

Haemopoeitic stem cells

Question 18

Name the haemopoietic cells with a myeloid precursor

Answer 18

RBCs, platelets, granulocytes (neutrophils, basophils, eosinophils), macrophages and dendritic cells

Question 19

Name the haemopoietic cells with a lymphoid precursor

Answer 19

T cells, NK cells, B cells and dendritic cells

Question 20

Where do haemopoietic stem cells originate in embryos?

Answer 20

Mesoderm

Question 21

When do the liver and bone marrow begin haemopoiesis in embryos?

Answer 21

• Liver starts by week 6
• Bone marrow starts by week 16

Question 22

Where does haemopoiesis occur in adults?

Answer 22

Bone marrow exclusively - axial skeleton, pelvis and proximal long bones

Question 23

Where is a bone marrow biopsy performed in children and in adults respectively?

Answer 23

• Children - tibia
• Adults - iliac crests

Question 24

What are the compartments of bone marrow?

Answer 24

• Cellular - haemopoietic cells and non-haemopoietic cells e.g. adipocyes, osteoclasts, osteoblasts
• Connective tissue matrix
• Vascular elements

Question 25

What are venous sinuses and what are their role in bone marrow vasculature?

Answer 25

• In contrast to capillaries, sinuses are larger and have a discontinuous membrane
• Arterioles drain into sinuses - wide venous vessels, which open into larger central sinuses

Question 26

What is the function of the adventitial cells located on bone marrow sinuses?

Answer 26

They contain smooth muscle fibres and so can contract to open or close the sinus

Question 27

How do formed blood cells enter the circulation?

Answer 27

They pass through fenestrations in endothelial cells

Question 28

What is the release of red cells associated with?

Answer 28

Sinusoidal dilatation and increased blood flow

Question 29

What cell type actively migrates towards the sinusoid during release of red cells into the circulation?

Answer 29

Neutrophils

Question 30

What do megakaryocytes do during release of red cells from the marrow?

Answer 30

Extend long branching processes called proplatelets into the sinusoidal blood vessels

Question 31

What is the difference between red and yellow marrow and when does yellow marrow increase?

Answer 31

• Red marrow is haemopoietically active, yellow marrow is not (fatty marrow)
• Increase in yellow marrow is seen with age which results in reduction in marrow cellularity in older individuals

Question 32

What is the myeloid:erythroid ratio, what is the normal value and when can this change?

Answer 32

• Relationship of neutrophils and precursors to proportion of nucleated red cell precursors
• Ranges from 1.5:1 to 3.3:1 i.e. myeloid is higher than erythroid in health
• Can reverse in people with anaemia and people who are haemolysing as this stimulates a compensatory response in the erythroid cells

Question 33

What is shown in the following diagram in relation to regulation of haemopoiesis?

Answer 33

• Erythroid islands - ‘nurse’ macrophages
• Macrophage is in center

Question 34

What regulates neutrophil precursor maturation?

Answer 34

• G-CSF
• Granulocyte colony stimulating factor

Question 35

What is the name of the substance that regulates growth and development of megakaryocytes from their precursors?

Answer 35

Thrombopoietin

Question 36

How is haemopoiesis investigated?

Answer 36

• Blood count, cell indices, morphology (blood film)
• Less common - bone marrow examination

Question 37

In which kind of cells is blood count/morphological assessment often sufficient?

Answer 37

Non-lymphoid cells e.g. granulocytes, plasma cells, RBCs

Question 38

What is the name for investigating antigen expression using specific antibodies (indicating lineage or stage of development)? In what cell type is this test requried?

Answer 38

• Immunophenotyping
• Required for lymphoid cells e.g. B cells, T cells