Haematopoiesis

Question 1

Definition of haematopoiesis

Answer 1

Process by which blood cells are generated from precursor cells

Question 2

Definition of totipotent

Answer 2

Stem cells that can divide to produce all differentiated cells in an organism (zygote)

Question 3

Definition of pluripotent

Answer 3

Stem cells that can divide into endoderm, mesoderm or ectoderm
All blood cells arise from a common pluripotent stem cell

Question 4

Definition of multipotent

Answer 4

Stem cell that has the ability to divide into a restricted no of cell types

Question 5

Definition of unipotent/progenitor

Answer 5

Restricted to a single lineage
Multiplication regulated by a lineage specific growth factors
No self renewal

Question 6

Definition of haematopoietic stem cells

Answer 6

Give rise to all circulating blood cells

Question 7

Definition of platelet demarcation channels

Answer 7

Platelets are held here within cytoplasm and are released when ER vesicles fuse with the cell membrane

Question 8

What is the composition of blood

Answer 8

Plasma (50-60% of BV)
-Contains soluble proteins, mediators

Packed cells

• Haematocrit (RBCs, 40-45% of BV)
• WBC, platelets

Question 9

Location 
Size
Volume
What % of blood is made up of RBCs
Lifespan
Organelles found here

Answer 9

Blood vessels
7um
4.8-5.5x10 12/L
45% v/v
120 days
Lack organelles, have glycolysis enzymes

Question 10

What is the difference between a normoblast and reticulocyte

Answer 10

Normoblast (8-10um)

• found in BM
• has mitochondria, ribosomes, nucleus (lost as it enters blood)

Reticulocyte

• 1-2 days needed to lose RNA, organelles
• 1% of blood

Question 11

Location
Size
Volume
Lifespan 
Shape
How are platelets produced

Answer 11

Blood
2-4um
150-400x10 9/L
8-12 days
Unclear discoid
Produced in BM form megakaryocytic fragments via thrombopoietin

Question 12

Location
Size
Nucleus shape
How do megakaryocytes release platelets

Answer 12

BM
50-70um
Polyploidy large irregular nucleus
Platelets held in platelet demarcation channels, released from vesicles

Question 13

Location
Volume
What % of BV do WBCs make up

Answer 13

Blood and tissues
4-11 x 10 9/L
<1% v/v

Question 14

What % of BV do neutrophils make up
Lifespan
Nucleus shape
Granule contents and their function

Answer 14

60% of WBC
6.7hr half life

Polymorphonuclear, move via chemokine gradients

Granules used in phagocytosis

• acid hydrolase
• neutral protease
• microbicides

Question 15

Location
What % of BV do eosinophils make up
Lifespan
Nucleus shape
Granule contents and their function

Answer 15

GI
1% of WBC
A few days
Bilobed nucleus

Basic proteins
Cationic proteins
Neurotoxins
Peroxidases

Question 16

Location
Nucleus shape of monocytes
Size

Answer 16

Blood
Kidney mononucleus
20um

Question 17

B cell shape and nucleus structure

Size

Answer 17

Condensed nucleus with surface AB

6-9um

Question 18

Plasma cell function

Size

Answer 18

Release AB

9-15um

Question 19

NK cell function

Size

Answer 19

Kill tumor/viral infected cells

9-15um

Question 20

T cell types and function

Size

Answer 20

Helper, cytotoxic

6-9um

Question 21

Describe the

• site prenatally and postnatally
• start of haematopoesis prenatally
• steps involved

Answer 21

Prenatal from month 7 onward => BM
Postnatal in larger bones
Lymphocyte prod continues in lymph nodes in life

2-2.5 weeks in utero
Blood islands surrounded by endothelium, surrounded by mesenchyme

Myeloid/lymphoid stem cell
Progenitor
Precursor
Differentiated functional cell in the blood

Question 22

Describe the macrostructure of the BM

Answer 22

Periosteal, endosteal capillaries supply bone and anastomose
BM made up of medullary vascular sinus in medullary cavity

Haematopoiesis occurs in the medullary cavity outside the sinus, supported by adventitial reticular cells structurally

Question 23

Describe the steps in RBC development

• stem cell division
• RBC protein synth
• enucleation
• maturation

Answer 23

Stem cell division
-mitotic division => gets smaller, nucleus condenses

RBC protein synth

• Fe receptor => moves Fe into cell and mitochondria
• Fe+ protoporphyrin =haem
• combines with a, b globing chain => haemoglobin

Enucleation

• gather around nurse macrophages
• normoblasts enucleated => reticulocyte

Maturation

• reticulocutes travel to spleen
• loses organelles

Question 24

Describe how neutrophils move

Answer 24

Have a pseudopod that retracts
Uropod provides traction
Move down chemokine/chemical gradient