Haematopoeisis

Question 1

What is haematopoiesis

Answer 1

The production of blood cells throughout life

Question 2

How long do neutrophils last

Answer 2

1 day

Question 3

How long do platelets last

Answer 3

7-10 days

Question 4

How long do rbcs live

Answer 4

120 days

Question 5

How long do lymphocytes and monocytes live

Answer 5

Months or years

Question 6

All blood cells arise from what type of cell

Answer 6

Haematopoietic Stem Cells

Question 7

What is a stem cell

Answer 7

A cell that has the ability to continuously divide and differentiate into various other kinds of cells/tissues

Question 8

Who demonstrated the existence of stem cells

Answer 8

Dr James Till

Dr Ernest McCulloch

Question 9

Where do stem cells come from

Answer 9

In research they come from IVF embryos that have been donated

Stem cells are taken from these blastocysts

Inner cell mast of blastocyst is taken

Question 10

What are the sites of haematopoiesis

Answer 10

Bone marrow

Yolk sac

Liver

Spleen

Bone marrow

Question 11

How many days does it take for an egg to become a blastocyst

Answer 11

6 days

Question 12

List the sites of haematopoiesis, from most cells produced to least from month one of development into adulthood

Answer 12

Yolk sac

Liver + spleen

Liver

Bone marrow

Question 13

Comment on the bone marrow during childhood

Answer 13

Childhood marrow volume increases as child grows

Average 3 year old has 1500 ml active marrow

As child grows fat cells accumulate in marrow to form yellow marrow

Adults have approx 30% active (red) marrow

Question 14

What happens to haematopoeisis if blood cell levels are low

Answer 14

Bone marrow can increase from 30% active to 100% active

Extramedullary haematopoeisis in liver and spleen may also re-occur (in disease)

Question 15

What does totipotent mean

Answer 15

Can develop into any cell type

Question 16

What does pluripotent mean

Answer 16

Can develop into some cell types

Question 17

List some characteristics of stem cells
(6)

Answer 17

Unspecialised
Capable of dividing and renewing themselves for long periods of time
Can differentiate into specialised cell types
Many different functions
Function altered in disease states
Mature cells have short half life

Question 18

How many Haematopoietic stem cells do we have

Answer 18

Limited number

1 per 20 million nucleated cells

Question 19

How many cells can a HSC make after 20 divisions

Answer 19

1 million cells

Question 20

What CD molecule do HSCs express

Answer 20

CD34

Question 21

What are the two pathways of haematopoiesis

Answer 21

Common myeloid pathway

Common lymphoid pathway

Question 22

What two cells can the HSC differentiate into

Answer 22

Common lymphoid precursor

Common myeloid progenitor

Question 23

What cell types result from the myeloid pathway
(7)

Answer 23

Thrombocyte

Erythrocyte

Mast cell

Basophil

Neutrophil

Eosinophil

Macrophage

Question 24

What cell types result from the lymphoid pathway
(3)

Answer 24

Natural killer cell

T lymphocyte

B lymphocyte (-> plasma cell)

Question 25

What is the common myeloid progenitor often called

Answer 25

CFU-GEMM

Question 26

What does CFU-GEMM stand for

Answer 26

Colony forming unit Granulocytes, erythrocytes, monocyte, megakaryocyte

Question 27

What is the common lymphoid precursor often called

Answer 27

CFU-L Colony forming unit - Lymphocytes

Question 28

How does a stem cell know what it is going to become

Answer 28

It depends what acts on it e.g. hormones such as erythropoietin stimulating the formation of rbc

Question 29

What is SCF

Answer 29

Stem cell factor

Question 30

What does stem cell factor do

Answer 30

Stimulates the self renewal of pluripotent stem cells -> makes more Acts on unipotent stem cells to make rbcs, platelets or wbcs

Question 31

What is needed for stimulation of erythropoiesis

Answer 31

Granulocyte-macrophage colony stimulating factor EPO

Question 32

What is needed for stimulation of thrombopoiesis

Answer 32

Granulocyte-macrophage colony stimulating factor Thrombopoietin

Question 33

What is needed for the stimulation of wbcs

Answer 33

Granulocyte-macrophage colony stimulating factor Lymphocytes -> need no more stimulation Monocytes need macrocytic colony stimulating factor Granulocytes need granulocyte colony stimulating factor

Question 34

How can growth factors for certain cell types be important in donations

Answer 34

These factors can be given to mobilise certain cell types out into peripheral blood so they can be donated easily

Question 35

What stages of erythropoietin happen in blood

Answer 35

Last two stages -> in rare occasions steps before are seen especially in blood loss

Question 36

Why does high reticulocytes mean

Answer 36

Loosing blood somehow

Question 37

What does the presence of nucleated rbcs mean in peripheral blood

Answer 37

Bone marrow is under a lot of pressure to recover rbc count

Question 38

List the steps involved in erythropoiesis (6)

Answer 38

Pronormoblast Early normoblasts Intermediate (polychromatic) normoblasts Late (pyknotic) normoblasts Reticulocytes Red cells

Question 39

List the cells in simplified erythropoiesis (5)

Answer 39

Megakaryocyte-erythrocyte progenitor Pro-erythroblast Erythroblast Reticulocyte Erythrocyte

Question 40

List the cells in thrombopoiesis

Answer 40

Megakaryocyte-Erythrocyte Progenitor Megakaryocyte broken into platelets after TPO stimulation

Question 41

What happens when granulocyte-monocyte progenitor is stimulated by G-CSF

Answer 41

Neutrophil is formed

Question 42

What happens when granulocyte-monocyte progenitor is stimulated by stem cell factor

Answer 42

Basophil is formed -> can be converted to a mast cell in tissues

Question 43

What happens when granulocyte-monocyte progenitor is stimulated by IL-5

Answer 43

Eosinophil is formed

Question 44

What happens when granulocyte-monocyte progenitor is stimulated by M-CSF

Answer 44

Monocyte is formed Converted into macrophage in tissues

Question 45

What does Growth factor (G-CSF) do

Answer 45

Matures cells e.g. neutrophils Helps cells differentiate Stops cell becoming other cell types Suppresses apoptosis Activates cells e.g. phagocytes Helps cells proliferate

Question 46

List the cells in the development pathway of a granulocyte (9)

Answer 46

HSC (Haemopoietic stem cells) CFU-GEMM (common myeloid progenitor) CFU- GM (granulocyte + monocyte precursor) CFU-Neut Myeloblast Promyelocyte Myelocyte Metamyelocyte Mature neutrophil

Question 47

What five stages come after GM-CFU in the development of a neutrophil

Answer 47

CFU-Neut Myeloblast Promyelocyte Myelocyte Metamyelocyte Mature neutrophil

Question 48

What are we looking for in bone marrow samples

Answer 48

Myeloid : Erythroid ratio Done by counting 200 to 300 cells

Question 49

Why do you need to know the age of the patient before assessing cellularity of bone marrow

Answer 49

Young child has 80% of the intertrabecular space occupied by haematopoietic cells 75 year old has only about 30%

Question 50

What does a really dark stain of bone marrow mean?

Answer 50

Leukaemia usually -> very little fat presence -> hypercellular

Question 51

What does a light stain of bone marrow mean

Answer 51

Aplastic anaemia -> hypocellular -> haematopoietic cells replaced by fat cells

Question 52

What stain do we use on bone marrow

Answer 52

Wrights Stain

Question 53

What stain do we use on bone marrow to test for iron

Answer 53

Perls Prussian Blue

Question 54

What happens to iron in bone marrow

Answer 54

10 to 20% of absorbed iron goes into a storage pool in cells of the mononuclear phagocyte system particularly fixed macrophages Its also recycled into erythropoiesis so theres a balance of storage and use