Haemopoeisis

Question 1

what are the mature blood cell types

Answer 1

red cells
-erythrocytes

platelets

White cells

• Granulocytes (neutrophils, eosinophils, basophils)
• monocytes (macrophages)
• lymphocytes (B cells, T cells, NK cells)

Question 2

what makes up haemopoeissi

Answer 2

erythropoeiss
thrombopoeisis
myelopoeisis or granulopoesis
ly,pjopoiesis

Question 3

what is the lifespan of red cells

Answer 3

120 days

2.5 million are lost and produced per second to maintain levels

Question 4

what is the lifespan of neutrophils

Answer 4

7-8 hours

1-2 million per second re lost and produced

Question 5

what is the lifespan of platelets

Answer 5

7-10 days

1 million platelets are made every second

Question 6

how are platelets formed

Answer 6

budding of megakaryocytes

Question 7

what are reticulocytes

Answer 7

immediate RBC precurosors ‘polychromasia’

Question 8

what are myelocytes

Answer 8

nucleated precursor between neutrophils and neutroblasts

Question 9

what are ‘ blast’ cells

Answer 9

nucleated precursor cells

erythroblasts
myeloblasts

Question 10

what is the first cell in haemopoeisis

Answer 10

haemopoeitic stem cell

Question 11

4 general stages of haemopoesis

Answer 11

Stem cells
multipoint progenitors
oligolineage progenitors
mature cells

Question 12

What are the developmental events/stages in haemopoiesis

Answer 12

self-renewal (need to create more stem cells)

proliferation (increase in numbers)

differentiation (descendants commit to one or more lineages)

maturation (descendants acquire functional properties and stop proliferating)

apoptosis (descendants undergo cell death)

Question 13

what are the sites of haemopoesis in the fetus

Answer 13

yolk sac - first side of erythroid activity, stops by week 10

Liver starts at week 6

bone marrow takes over at week 16

Question 14

where do haemopoeitic cells come from embryonically

Answer 14

the mesoderm

Question 15

where is haemopoeisis in adults

Answer 15

bone marrow within

axial skeleton
pelvic
long bones

Question 16

where do you take a bone marrow biopsy in a child vs and adult and why

Answer 16

child - femur/tibia as that is where the most haemopoesis occurs

adults - posterior iliac crest as that is where the most haempoeisis occurs

older people - vertebrae, sternum and ribs have the most haemopoesis

Question 17

what is bone marrow

Answer 17

a complex organ surrounded by a shell of bone with a neuromuscular supply

Question 18

What are the microscopic compartments of the bone marrow

Answer 18

Cellular (haemopoeitic cells and non-haemopoeitic cells - adipocytes, fibroblasts, osteoclasts, osteoblasts)

connective tissue matrix

vascular elements

Question 19

how is blood supplied to the bone marrow

Answer 19

‘Venous sinuses’

arterioles drain into ‘sinuses’ which are wide venous vessels opening into a larger central sinus

Question 20

difference between sinuses and capillaries

Answer 20

sinuses are larger and have a discontinuous basement membrane (lots of gaps in it)

Question 21

what are the gaps between endothelial cells in the bone marrow sinus’s called

Answer 21

fenestrations

Question 22

how do mature cells leave the marrow and enter the circulation

Answer 22

pass through fenestrations into the venous sinus

release of red cells causes dilation of the sinuses and increased blood flow

Question 23

how do neutrophils get into the bone marrow sinuses

Answer 23

active migration

Question 24

how do platelets get into the venous sinuses

Answer 24

megalokaryocytes extend long branching processes (proplateletes) into the sinusoidal blood vessel

Question 25

what is the difference between red and yellow marrow

Answer 25

red marrow - haemopoietically active

yellow marrow - fatty haemopoietically inactive

Question 26

what happens to bone barrow due to ageing

Answer 26

increase of yellow marrow with age resulting in a reduction in marrow cellularity in older people

Question 27

what is the myeloid:erythroid ratio

Answer 27

relationship of neutrophils and precursors to proportion of nucleated red cell precursors

(is reserves in haemolysis as a compensatory response)

usually between 1.5:1 and 3.3:1

Question 28

what regulates haemopoiesis

Answer 28

intrinsic properties of cells (eg. stem cells vs progenitor cells vs mature cells)

signals from immediate surroundings and periphery (microenvironmental factors)

specific anatomical area (niche) for optimal developmental signals

Question 29

what regulates neutrophil precursor maturation

Answer 29

G-CSF

granulocyte colony stimulating factor

Question 30

what regulates growth and development of megakaryocytes

Answer 30

thrombopoietin

Question 31

what microenvironmental factors regulate haemopoiesis

Answer 31

the niche environment which the cell is in

different cytokines in the environment

Nice environment is altered in disease states or with therapy

Question 32

investigations for haemopoeiss

Answer 32

Blood count
Cell indices
morphology

less common - specialise bone marrow examination

Question 33

investigations for mature cell counts

Answer 33

non-lymphoid cells - blood count/morphology is sufficient

lymphoid cells often need immunophenootyping using specific antibodies to tell what lineage or stage of development they are

Question 34

what is immunophenotyping

Answer 34

identifying patterns of protein (antigen) expression unique to a cell lineage

use antibodies (in combination) specific to the antigens