Introduction to Haematopoiesis

Question 1

Define ‘haematopoiesis’

Answer 1

Development of all cellular components of blood

Question 2

List the sites of haematopoiesis in the foetus

Answer 2

• Aorta gonad mesonephros (AGM) - Yolk sac - Placenta - Liver - Spleen

Question 3

List the sites of haematopoiesis in the adult

Answer 3

• Bone Marrow - Maturation in thymus, lymph nodes, and spleen

Question 4

Define haematopoietic stem cells (HSCs)

Answer 4

precursor cells for all blood components.

Question 5

Location of haematopoietic stem cells

Answer 5

Located in adult bone marrow

Question 6

List two types of haematopoietic stem cells (HSCs)

Answer 6

Primitive and definitive

Question 7

When do primitive HSCs develop?

Answer 7

Day 13-15 in human embryo

Question 8

What do primitive HSCs develop into?

Answer 8

Primitive nucleated RBC with embryonic haemoglobin.

Question 9

Primitive HSCs have a self-renewing capacity

Answer 9

False, they don’t.

Question 10

When do definitive HSCs develop?

Answer 10

Develops in day 32-33 in humans.

Question 11

Where do definitive HSCs occur?

Answer 11

Occurs in yolk sac, aorta gonad mesonephros (AGM), and placenta.

Question 12

What do definitive HSCs develop into?

Answer 12

Myeloid and lymphoid progenitor cells.

Question 13

Definitive HSCs have a self-renewing capacity.

Answer 13

True

Question 14

What is the bone marrow niche?

Answer 14

Bone marrow niche (stem cell niche) is an anatomical site where: - Stem cells are maintained and reproduce - Stem cell differentiation is inhibited (i.e. stem cells keep multipotency) - Number of stem cells are limited.

Question 15

Once stem cells leave stem cell niche (bone marrow niche), they have limited self-renewal capacity

Answer 15

True

Question 16

In adults, bone marrow niche is located where?

Answer 16

Located at proximal ends of long bones.

Question 17

Where are quiescent HSCs (G0) maintained?

Answer 17

They are maintained near arterioles.

Question 18

Function of B-cells as a lymphoid progenitor?

Answer 18

Adaptive antibody production

Question 19

List the T-cells of the lymphoid progenitors

Answer 19

• CD4+ Helper T cells
• CD8+ Killer T cells
• Suppressor T cells
• Memory T cells

Question 20

Remember the lineages of the HSCs

Answer 20

Question 21

Function of CD4+ Helper T cells

Answer 21

Release chemokines that act on other immune cells

Question 22

Function of CD8+ Killer T cells

Answer 22

Kill microorganisms and tissue cells invaded by viruses

Question 23

Function of Suppressor T cells

Answer 23

Suppress killer and helper T cells to prevent autoimmune damage

Question 24

Function of Memory T cells

Answer 24

Activated by antigens to provide powerful response to duplicate antigen

Question 25

List the myeloid progenitors

Answer 25

- Platelets - Monocytes - Basophils - Neutrophil - Eosinophil - Erythryocytes

Question 26

What are platelets?

Answer 26

Produced by megakaryocytes; promote clotting

Question 27

Describe monocytes

Answer 27

These differentiate into dendritic cells and macrophages

Question 28

Function of basophils

Answer 28

Fight parasitic infection

Question 29

Function of neutrophils

Answer 29

50% for leukocytes in blood; pathogen fighting cells

Question 30

Function of eosinophils

Answer 30

Fights bacteria, viral and parasitic infection; role in allergies

Question 31

Describe erythryocytes (RBC)

Answer 31

Biconcave, anucleate cells that transport oxygen in blood

Question 32

Describe erythroblast

Answer 32

Immature RBC with nucleus still

Question 33

Describe reticulocyte

Answer 33

Round, immature RBC right after nucleus is ejected.