Haemopoiesis

Question 1

most appropriate site for bone marrow examination?

Answer 1

posterior iliac crest

Question 2

most appropriate technique to assign cell lineage?

Answer 2

..

Question 3

what is haemopoiesis?

Answer 3

formation of blood cells

Question 4

3 categories of mature blood cells?

Answer 4

red cells
platelets
white cells

Question 5

only which category of blood cells have a nucleus?

Answer 5

white cells

Question 6

categories of white cells?

Answer 6

granulocytes
monocytes
lymphocytes

Question 7

types of granulocytes?

Answer 7

neutrophils
eosinophils
basophils

Question 8

function of neutrophils?

Answer 8

phagocytosis/acute inflammation

Question 9

function of eosinophils?

Answer 9

destroy parasites

modulate hypersensitivity reactions

Question 10

function of basophils?

Answer 10

modulate hypersensitivity

Question 11

types of monocytes and their function?

Answer 11

macrophages
modulate immune reactions
phagocytic clearance
regulatory functions

Question 12

types of lymphocytes?

Answer 12

B cells (humoral immunity - antibodies)
T cells (cell mediated immunity, regulatory functions)
NK cells (anti-viral/tumour)

Question 13

haemopoiesis encompasses what processes?

Answer 13

myelopoiesis or granulopoiesis
erythropoiesis
thrombopoiesis
lymphopoiesis

Question 14

lifespan of RBCs?

Answer 14

120 days

Question 15

neutrophils lifespan?

Answer 15

7-8 hours

Question 16

lifespan of platelets?

Answer 16

7-10 days

Question 17

how many RBCs produced and lost per second?

Answer 17

2.5 million

Question 18

how many neutrophils produced and lost per second?

Answer 18

1-2 million

Question 19

how many platelets are produced per second?

Answer 19

1 million

Question 20

“blast” suffix means?

Answer 20

nucleated precursor cell
erythroblast = RBC precursor
myeloblast = granulocyte precursor??

Question 21

what are megakaryocytes?

Answer 21

immediate RBC precursor

polychromatic and not nucleated

Question 22

what are myelocytes?

Answer 22

nucleuated precursor between myeloblast and neutrophil

Question 23

where do precursor blood cells come from?

Answer 23

haemopoietic progenitor cells

Question 24

where do progenitor cells and ultimately all haemopoietic cells come from?

Answer 24

haemopoietic stem cells

stem cells > multipotent progenitors > oligolineage progenitors > mature cells

Question 25

what developmental events occur in haemopoiesis?

Answer 25

self renewal proliferation (increase in numbers) differentiation (descendents commit to one or more lineages) maturation (descendents acquire functional properties and may stop proliferating) apoptosis (descendents undergo cell death) - events can overlap

Question 26

describe activity of more primitive progenitors (eg stem cells) during steady state haemopoiesis (where production equals death)?

Answer 26

cells are quiescent/dormant

Question 27

what does myeloid terminology refer to?

Answer 27

marrow lineage or marrow malignancy (non-lymphoid)

Question 28

where do haemopoietic stem cells originate embryonically?

Answer 28

in the mesoderm

Question 29

when do committed progenitor cells become detectable in the circulation?

Answer 29

week 5

Question 30

first site of erythroid activity?

Answer 30

yolk sac | stops by week 10

Question 31

when does erythroid activity begin in the liver?

Answer 31

week 6

Question 32

when does erythroid activity begin in the bone marrow?

Answer 32

week 16 | continues until adulthood within axial skeleton, pelvis and proximal long bones

Question 33

bone marrow sites of erythroid activity during growth after birth?

Answer 33

activity in tibia and femur reduces by 20-30 | mostly in vertebra > sternum > ribs throughout life

Question 34

describe bone marrow structure

Answer 34

complex organ surrounded by shell of bone with a neurovascular supply

Question 35

compartments of bone marrow under the microscope?

Answer 35

cellular (haemopoietic cells and non-haemopoietic cells) connective tissue matrix vascular elements

Question 36

what non-haemopoietic cells are found in bone marrow?

Answer 36

adipocytes fibroblasts osteoclasts osteoblasts

Question 37

describe the bone marrow vasculature

Answer 37

made of nutrient artery and periosteal network | arterioles drain into sinuses (wide venous vessels) which open into larger central sinuses

Question 38

how are sinuses different to capillaries?

Answer 38

sinuses are larger and have a discontinuous basement membrane

Question 39

what makes up the bone marrow sinus?

Answer 39

central canal lined by endothelial cells sitting on top of a basement membrane endothelial cells connected via tight junctions and fenestrations

Question 40

how are mature blood cells released from bone marrow?

Answer 40

formed blood cells can pass through fenestrations in endothelial cells to enter circulation

Question 41

release of RBCs is associated with what?

Answer 41

sinusoidal dilation and increased blood flow

Question 42

where do neutrophils actively migrate towards

Answer 42

the sinusoid

Question 43

how are megakaryocytes released into circulation?

Answer 43

extend long branching processes called proplatelets into the sinusoidal blood vessels platelets bud off

Question 44

red marrow?

Answer 44

haemopoietically active marrow

Question 45

yellow marrow?

Answer 45

fatty, inactive marrow

Question 46

which type of marrow increases with age? what does this cause?

Answer 46

yellow | results in reduction in marrow cellularity in older individuals

Question 47

what is the myeloid:erythroid ratio?

Answer 47

relationship of neutrophils and precursors to proportion of nucleated RBC precursors ranges from 1.5:1 and 3.3:1 subsequent to change (e.g ratio reversed in haemolysis)

Question 48

what regulates haemopoiesis?

Answer 48

intrinsic properties of cells signals from immediate surroundings and periphery (microenvironmental factors) specific anatomical area (niche) for optimal developmental signals