Haemopoiesis

Question 1

definition of Haemopoiesis?

Answer 1

formation of blood cells

Question 2

Give the 3 main types of blood cells and their subgroups and functions?

Answer 2

Red cells
Erythrocytes- transport O2/Co2

Platelets
Primary Haemostasis

White cells
Granulocytes
-Neutrophils, phagocytosis + acute inflammation
-Eosinophils, destroy parasites + modulate hypersensitivity reactions
-Basophils, modulate hypersensitivity rections

Monocytes --> Macrophages 
modulate immune reactions
Phagocytic clearance 
Lymphocytes
regulatory functions 

Lymphocytes

• B cells, produce antibodies
• T cells, cell mediate immunity + regulatory functions
• NK cells, anti viral/tumour

Question 3

describe what kind of nucleus granulocytes have

Answer 3

segmented

Question 4

state the lifespan of RBCs, Neutrophils & platelets?

-why is this relevant?

Answer 4

RBCs- 120 days
neutrophils- 7-8 hrs
Platelets- 7-10 days

-if bone marrow suddenly shuts down neutrophils will be the first to drop

Question 5

what are erythroblasts and myeloblasts?

what are reticulocytes?

Answer 5

name the primitive nucleated precursor for erythroblasts and myeloblasts

-immediate red cell precursor, polychromasia if in increased levels

Question 6

What are Megakaryocytes?

What are Myelocytes?

Answer 6

• platelet precursor, polyploid

- nucleated precursor between neutrophils and blasts

Question 7

Name the cell that produces precursor blood cells

Answer 7

haemopoetic progenitor cell

Question 8

Name the cell that produces progenitor cells?

Answer 8

haemopoitic stem cells

Question 9

Give the sites of haemopoiesis at each stage of development:

• Where are all haemopoitic stem cells derived from?
• wk 5- wk 10
• wk 6
• week 12
• wk 16
• adulthood

Answer 9

• mesoderm
• yolk sac
• liver
• spleen (small contribution)
• bone marrow
• axial skeleton- vertebra/sternum/ribs

Question 10

where are bone marrow biopsies collected in:

• children?
• adults?

Answer 10

• shaft of the tibia
• illiac crest or sternum

OR can mobilise stem cells from the marrow into blood for collection and transplantation

Question 11

give the 3 different compartments in the bone marrow?

• where is the most haemopoetic activity?
• what is the endosteum?

Answer 11

cellular
(haemopoietic cells and non haemopoitic cells)
Vascular elements
connective tissue matrix

• trabecular bone, found throughout the metaphysis such that many cells in this region are close to the bone surface
• the interface between bone and bone marrow, covered by bone lining cells

Question 12

• what are sinusoids?
• what is their function?
• describe the vascular relationship of the sinusoids?

Answer 12

specialised venues that form a reticular network of fenestrated vessels

• to regulate the passage of cells in and out of the circulation
• arteries feed into the sinusoids

Question 13

what do reticular cells do in th bone marrow?

Answer 13

contains smooth muscle and can contract and regulate opening of holes between endothelial cells and the BM

Question 14

• how do mature cells enter the circulation?

- how do different cell types travel to the sinusoid?

Answer 14

-can pass through fenestrations in endothelial cells to enter circulation

-neutrophils actively migrate towards the sinusoid
Megakaryocytes extend long branches called pro platelets into the sinusoidal vessels
RBC release assoc with sinusoidal dilatation and inc blood flow

Question 15

• what is the difference between red bone marrow and yellow bone marrow?
• what happens within the bone marrow with age?

Answer 15

Red- haemopoietically active
yellow- fatty, inactive marrow
there is a reduction in marrow cellularity with age

Question 16

what is the myeloid:erythroid ratio?

-how might it change in haemolysis?

Answer 16

the relationship of neutrophils and precursors to proportion of nucleated red cell precursors (from 1.5:1 to 3.3:1)

-see an increase in erythroid activity and the ratio reverses

Question 17

haemopoiesis regulation
-how is haemopoiesis regulated?
-what regulates neutrophil maturation?
-what regulates the growth of megakaryocytic from their precursors
-

Answer 17

interplay of random intrinsic properties of cells (stem cells) nd signals from immediate surroundings and the periphery
+ activation of lineage specific transcription factors

• G-CSF
• Thrombopoietin

Question 18

why are cells located in different places within the bone marrow?
what is are the 2 clinical indications fro this?

Answer 18

the haemopoitic niche exists for the haemopoitic stem cell

• Niche can shift in states of marrow stress
• drug can be used to mobilise HSC from niche for collection and transplantation

Question 19

How do you asses haemopoiesis?

Answer 19

blood count
cell indices
morphology

less commonly: bone marrow examination

Question 20

how might you asses precursor cells?

-how does this work?

Answer 20

expression of antigens indicating lineage or take of development can be studied in /on cells = Immunophenotyping

-identify patterns of antigen expression unique to cell lineage and use antibodies specific to different antigens

Question 21

How are donated stem cells collected?

• what is the issue with this method?
• how is it resolved?

Answer 21

• collected due to specific gravity
• the specific gravity and morphology is fairly similar in all WBCs
• Use antibodies with fluorescent markers to distinguish between CD3/CD34 then use flow cytometry to determine the volume of stem cells gathered