Haemopoeisis

Question 1

What is haemopoeisis

Answer 1

formation of blood cells

Question 2

what is erythropoeisis

Answer 2

formation of RBCs

Question 3

what is myelopoeisis

Answer 3

formation of white blood cells - granulocytes and monocytes

Question 4

what is lymphopoeisis

Answer 4

formation of lymphocytes

Question 5

what is thrombopoeisis

Answer 5

formation of platelets

Question 6

in the steady state, cell loss is balanced by cell production, true or false

Answer 6

true

Question 7

what is the normal average lifespan of RBCs

Answer 7

120 days

Question 8

what is the normal average lifespan of neutrophils

Answer 8

7-8 hours

Question 9

what is the normal average lifespan of platelets

Answer 9

7-10 days

Question 10

what are “blasts”

give examples

Answer 10

nucleated precursor cells
erythroblasts
myeloblasts

Question 11

what are megakaryocytes

Answer 11

polyploid platelet precursor cells

Question 12

what are reticulocytes

Answer 12

immediate mature RBC precursor

polychromatic

Question 13

what are myelocytes

Answer 13

nucleated precursor between neutrophils and “blasts”

Question 14

stem cells are dormant/active during steady state haemopoeisis

Answer 14

dormant

Question 15

what are the steps in the haemopoeitic tree

Answer 15

Self renewal 
Proliferation 
Differentiation/lineage commitment 
Maturation 
Apoptosis

Question 16

from which germ layer do haemopoeitic stem cells arise

Answer 16

mesoderm

Question 17

where is the first site of haemopoeisis in a foetus

Answer 17

yolk sac

stops at week 10

Question 18

in the foetus, where is another site of haemopoeisis at week 6

Answer 18

liver

Question 19

at week 16 in the foetus, what is another site of haemopoeisis

Answer 19

bone marrow

Question 20

where is haemopoeisis in an adult

Answer 20

in the bone marrow of the axial skeleton, pelvis and proximal long bones

Question 21

where would you take a bone marrow biopsy from in:
adults
children

Answer 21

adults - posterior iliac crest

children - proximal anterior tibia

Question 22

what is bone marrow

Answer 22

complex organ with a shell of bone and a neurovascular supply

Question 23

what are the 3 main compartments of bone marrow

Answer 23

cellular
vascular
connective tissue stroma

Question 24

what are the cellular components of bone marrow

Answer 24

haemopoeitic

non-haemopoeitic: adipose, osteoblasts, osteoclasts, fibroblasts

Question 25

describe the vasculature of bone marrow

Answer 25

network of thin walled fenestrated sinusoidal vessels | it is supplied by a nutrient artery

Question 26

what is the difference between venous sinuses and capillaries

Answer 26

venous sinuses are larger and have a discontinuous basement membrane (sinusoidal)

Question 27

what are sinusoids and where can you find them

Answer 27

irregular blood filled spaces with extra large fenestrations to allow passage of proteins/blood cells endothelial cells do not overlap each other found in bone marrow, liver and spleen

Question 28

describe the process of RBC leaving the bone marrow

Answer 28

they leave through sinusoids (fenestrations in endothelial cells) to enter circulation this is associated with sinusoidal dilatation and increased blood flow neutrophils actively migrate to the sinusoid megakaryocytes extend branches called proplatelets into sinusoidal blood vessels

Question 29

what is the difference between red and yellow bone marrow

Answer 29

``` red = haemopoeitically active yellow = fatty, inactive, increases with age ```

Question 30

what is the myeloid:erythrocyte ratio (M:E ratio) what is the benefit and what is the normal ratio

Answer 30

compares number of nucleated precursors of myeloid and erythroid cells it allows us to look at the production of these normally M:E is 1.5-3.3:1

Question 31

why can the M:E ratio be reversed

Answer 31

in haemolysis | as the bone marrow is trying to make more red cells to compensate

Question 32

how is haemopoeisis regulated

Answer 32

Intrinsic properties of the cell Microenvironmental factors/signals Anatomical location "niche" for optimal developmental signals

Question 33

where are macrophages nursed in haemopoeisis

Answer 33

erythrocyte islands

Question 34

what is G-CSF and what is its function

Answer 34

Granulocyte colony stimulating factor | regulates neutrophil precursor

Question 35

which hormone regulates growth of megakaryocytes from their precursor

Answer 35

thrombopoeitin

Question 36

where is the haemopoeitic stem cell niche located and how can it be affected

Answer 36

niche is located around vasculature to provide access to cytokines can be altered by disease or treatments

Question 37

what investigations are done for mature non-lymphoid cells

Answer 37

FBC cell indices blood film bone marrow aspiration

Question 38

what investigation is done for mature lymphoid cells

Answer 38

immunophenotyping

Question 39

what is immunophenotyping

Answer 39

study of antigen expression unique to a lineage using specific antibodies

Question 40

how is immunohistochemistry measured

Answer 40

flow cytometry