Haemopoiesis

Question 1

what does intramedullary haemopoiesis mean

Answer 1

haemopoiesis occurring in the bone marrow

Question 2

where else may haemopoiesis occur in certain pathological conditions

Answer 2

liver, lymph nodes and spleen

Question 3

where does haemopoeisis occur in embryo

Answer 3

yolk sac - area vasculosa (in blood islands)

Question 4

where are foetal precursor blood cells found

Answer 4

dorsal aorta

Question 5

when does mesoblastic phase occur and what is it

Answer 5

week 2-3 gestation, is the period of embryonic blood formation

Question 6

what are the three haemopoiesis stages

Answer 6

mesoblastic/embryonic
hepatosplenic phase
myeloid/bone marrow phase

Question 7

what is produced during the primitive haemopoiesis stage

Answer 7

mostly erythrocytes, and primitive haemoglobin (gower and portland) begin to form

Question 8

what occurs during hepatosplenic phase

Answer 8

involves the liver- main form of haemopoiesis at 4 months, and tyoe of production declines towards birth. production also occurs in the spleen to a lesser extent

Question 9

what type of Hb is produced during hepatosplenic phase

Answer 9

HbF

Question 9

when does the myeloid phase begin

Answer 9

5-9 months in foetus and continues through life.

Question 10

what happens when myeloid phase begins in foetus

Answer 10

production of HbA (main adult type of Hb)

Question 11

what bones contain marrow for haemopoeisis

Answer 11

sternum, hips, pelvis, ribs, vertebrae, femur, cranium (skull)

Question 12

what is the normal ratio of fat to haemopoietic cells in adults

Answer 12

1:1

Question 13

how many cells are produced in the bone marrow in healthy young adults

Answer 13

5-10 x 10^11

Question 14

what factors affect haemopoeisis

Answer 14

growth factors, cytokines, environmental factors, o2 levels in body

Question 15

what is the lifespan of mature granulocytes in blood

Answer 15

few hous

Question 16

what is the precursor stem cell

Answer 16

haemopoietic pluripotent stem cell

Question 17

what are the two characteristics of stem cells

Answer 17

1. ability to proliferate and create more cells
2. self renewal

Question 18

what are the stages in haemopoeitic cell development

Answer 18

1. stem cell
2. differentiation and lineage selection
3. maturation: non dividing cells will develop in mature cells
4. functional mature cells
5. cell death- apoptosis

Question 19

describe multipotent colony forming units (CFU-GEMM)

Answer 19

these cells proliferate and differentiate into mature cells of various myeloid lineages

Question 20

what are uni potent progenitor cells

Answer 20

CFU-E that produce cells that mature into erythrocytes

Question 21

what is a rich source of stem and progenitor cells apart from marrow

Answer 21

umbilical cord blood

Question 22

where can stem cells be found

Answer 22

among cells that have the CD34 cell markers. some drugs can increase CD34 production as it tells where stem cells are available to be harvested

Question 23

what regulates haemopoeisis

Answer 23

haemopoietic growth factors (glycoprotein hormones) regulate prolif and differentiation, and regulate balance between haemopoiesis and apoptosis. they react to external stresses i.e blood loss/infections

they bind to surface receptors on target cells and trigger replication, differentiation and functional activation

Question 24

what does CSF mean

Answer 24

colony stimulating factors (haemopoietic growth factors)

Question 25

name EPO, G CSF, M CSF, GM CSF, IL3, Thrombopoeitin , stem cell factor, VE functions

Answer 25

EPO - erythropoeitin- RBC production
G CSF- granulocyte
M CSF - Macrophage
GM -CSF - Granulocytes and macrophages
IL3 - interleukin 3 - iron uptake
Thrombopoeitin - platelets
Stem cell factor - stem cell activation
VE - vascular endothelial growth factor

Question 26

where is EPO, GMCSF, GCSF and Thrombopoeitin produced and where to they take effect

Answer 26

EPO- kidney- CFU-E- RBCs

GM-CSF - Fibroblasts/macrophages, bone marrow/stromal cells/endothelial cells- CFU-GM - Granulocytes/macrophages/monocytes

G-CSF - same as GM-CSF - CFU-GM - granulocytes (neutrophils)

Thrombopoietin - liver cells - CFU-Meg - megakaryocytes/ platelets

Question 27

what are the stages in interphase

Answer 27

G0 where the cells rest and are not proliferating.
G1 where the cell commits to replication
S where DNA is double
G2 where organelles and cytoplasm volume increases

Question 28

describe how rates of cell proliferation can be adjusted

Answer 28

• cells in G0 can be stimulated to start DNA synthesis
• the period in G1 can be shortened or prolonged, the same as S or G2.
• the duration as mitosis as a whole can vary
• cell development can be arrested in G2- causing cell death in certain Haemopoeisis disorders. Therapeutic drug regimes are designed to reduce cell populations are based on their effect on the cell cycle

Question 29

how can stem cells and growth factors be applied clinically

Answer 29

stem cells - transplanted to treat patients with haematological malignancies
- Haemopoietic growth factors can be produced by recombinant DNA techniques and used to treat patients with cytopenias
1. EPO - anaemia in kidney failure patients
2. G-CSF + GM-CSF can be treat leucopoenia
3. Thrombopoeitin - being researched to use it in thrombocytopenia