Hematopoisesis

Question 1

What are the two components of Bone Marrow ?

Answer 1

Hematopoietic Cell compartment

• Highly vascular
• Hemo stem cells

Marrow Stromal Compartment

• produce hema growth factors
• barrier ( endothelial cells)
• source of energy and synthesize growth factors(adipose cells)
• Removal of dead cells ( macrophages)

Question 2

Red vs Yellow Marrow

Answer 2

Red

• all bone marrow starts off as red in newborns
• have a lot of cells

Yellow

• presence of adipocytes
• as you age red becomes yellow

Question 3

Bone Marrow Structure

Answer 3

Stromal structure
Stroma : made of reticular connective tissue
adipocytes and macrophages
Hemapoietic cords
- Bundles of blood cells at different stages of maturation
Vascular Sinusoids
- btw cords
- lined with endothelial cells
- often have megakaryocytes discharging protoplatelets
into the sinusoid

Question 4

Hematopoietic stem cell

Answer 4

capable of self-renewal, can differentiate into rbc and wbc

Question 5

Hematopoietic Growth Factors

Answer 5

• control proliferative and maturational phases of hematopoiesis
• used for clinical treatments
• produced in bone marrow by endothelial cells, stromal cells, fibroblasts, developing lymphocytes and macrophages.

3 major groups

• colony stimulating factors(CSF)
• EPO and thrombopoietin (TPO)
• cytokines ( interleukins 3,2,6)

Question 6

Stem cell factor (SCF)

Answer 6

• also known as c-kit ligand or steel factor
• produced by fetal tissues and bone marrow
• weak stimulator of hematopoiesis
• makes stem cells responsive to other cytokines

Question 7

Flt3

Answer 7

• Closely related to SCF

- acts on pluripotent cells in synergy with TPO, SCF and interleukins

Question 8

IL- 3

Answer 8

• influences growth and replication potential of hematopoietic progenitors
• eg Basophil and Mast cell

Question 9

IL- 1 and 4

Answer 9

-acts on the pluripotent cell to develop lymphoid stem cells

Question 10

IL- 2

Answer 10

t- cell growth factor

Question 11

IL- 2 and 6

Answer 11

b- cell growth factor

Question 12

Granulocyte macrophage colony stimulating factor

GM-CSF

Answer 12

• stimulates the formation of all leukocytes and reticulocytes
• less potent than G-CSF for increasing neutrophils during neutropenia

Question 13

G- CSF

Granulocyte

Answer 13

• stimulates increase in neutrophils

- treatment for neutropenia after chemotherapy

Question 14

M- CSF

macrophage

Answer 14

stimulates increase in macrophages and monocytes

Question 15

EPO

Answer 15

produced in kidney and stimulates formation of RBC

Question 16

Thrombopoietin (TPO)

Answer 16

produced in liver and stimulates increase in megakaryocytes and platelets

Question 17

RBC’s

Answer 17

• deliver oxygen from lungs to tissues

- pick up co2 from tissues and unload it to lungs

Question 18

Platelets ( thrombocytes)

Answer 18

• secrete vasoconstrictors

- stick together to form platelet plug ( blood clot?)

Question 19

Erythropoiesis

Answer 19

pronormoblast ( ribosomes

Question 20

Neutrophils

Answer 20

• phagoctize bacteria

- release antimicrobial chemicals

Question 21

eosinophils

Answer 21

• phagocytize antigen-antibody complexes, allergens and inflammatory chemicals
• antiparastic and bactericidal activity

Question 22

basophils

Answer 22

• secrete histamine and heparin

- Inflammatory reactions during immune responses and allergies

Question 23

Monocytes

Answer 23

• become macrophages
• phagocytize pathogens, dead neutrophils and debris of dead cells
• present antigen to activate other cells of the immune system

Question 24

lymphocytes

Answer 24

b-cells : secrete antibodies. mature in bone marrow

t cells :destroy cancer, foreign and virus infected cells
mature in thymus.