Overview of Hematopoiesis

Question 1

Describe where hematopoiesis take places before birth

Answer 1

Yolk Sac (less than 6 weeks of age) Live and Spleen (6 weeks to 7 months) Bone Marrow (7 months until birth)

Question 2

Describe where hematopoiesis takes place after birth (in children)

Answer 2

All Bones

Question 3

Describe where hematopoiesis takes place as you age

Answer 3

Central Skeleton

Question 4

What supplies oxygenated blood to bone marrow?

Answer 4

Nutrient arteries and periosteal capillary network

Question 5

How does blood leave the bone marrow? What else leaves via this same pathway?

Answer 5

Sinusoids Hematopoietic cells released

Question 6

What is part of the extravascular compartment of bone marrow?

Answer 6

Actively replicating hematopoietic cells, Stroma (structural support), lymphoid tissue, nerves, and trabecular bone

Question 7

What makes up the stroma?

Answer 7

Fat cells, macrophges, reticular cells, and fibroblasts - all provide scaffolding

Question 8

What is a hematopoietic stem cell?

Answer 8

Gives rise to all blood cell types in bone marrow Most are mitotically quiescent (inactive) Produce differentiated cells - this is irreversibe

Question 9

What are progenitor cells?

Answer 9

They are committed cells that give rise to differentiated cells

Question 10

What are the first committed cells?

Answer 10

Lymphoid or Myeloid stem cells Myeloid stem cells become all non-lymphoid cells

Question 11

What cells are recognizable by microscopic examination?

Answer 11

Late precursors and mature blood cells

Question 12

What are non-lymphoid cells?

Answer 12

Neutrophils, Erythrophils, Platelets Monocytes

Question 13

What growth factor is required for hematopoiesis?

Answer 13

Stem cell factor (c-kit ligand) Needed for proliferation, migration, and adhesion of stem cell

Question 14

What growth factors act on multipotential progenitor cells?

Answer 14

IL-3 (interleukin 3) and GM-CSF (granulocyte/macrophage colony stimulating factor) Both stimulate proliferation of common myeloid progenitor

Question 15

What do committed myeloid cells differentiate into FIRST?

Answer 15

BFU-e (burst forming unit-erythroid)

Question 16

What do committed myeloid cells differentiate into SECOND?

Answer 16

CFU-e (burst forming unit - erythroid)

Question 17

What growth factor is important for erythroid cells? Where is it produced? At what moments is it produced?

Answer 17

Erythropoietin (EPO) Produced in kidney under hypoxic conditions

Question 18

What is the order of erythropoietin production?

Answer 18

Stem cell - Early BFU-E - Late BFU-E - CFU-E - Pronormalblast - Reticulocyte

Question 19

Where does erythropoietin act in the bone marrow?

Answer 19

Acts at BFU-E stage

Question 20

How long do red blood cells live?

Answer 20

120 days

Question 21

At what stage do red cell cells leave bone marrow?

Answer 21

Reticulocytes

Question 22

What is granulopoiesis?

Answer 22

Production of white blood cells

Question 23

What is erythropoiesis?

Answer 23

Production of red blood cells

Question 24

What is the committed stage in granulopoiesis?

Answer 24

CFU-GM (colony forming unit-granulocyte marcrophage)

Question 25

What stimulates CFU-GM?

Answer 25

GM-CSF (granulocyte monocyte colony stimulating factor) and IL-3

Question 26

What does CFU-GM differentiate into?

Answer 26

CFU-G (colony forming unit - granulocyte) CFU-M (colony forming unit - monocyte)

Question 27

What does CFU-M become?

Answer 27

Monoblast then Promonocyte then MONOCYTE

Question 28

What does CFU-G become?

Answer 28

Myeloblast then Promyelocyte then Myelocyte then Metamyelocyte then Band then Mature NEUTROPHIL

Question 29

What is megakaryopoiesis?

Answer 29

Production of platelets

Question 30

How long do platelets survive?

Answer 30

1 week

Question 31

How long do neutrophils (WBC) survive?

Answer 31

7 hours

Question 32

What is platelet production known as?

Answer 32

Thrombopoiesis or megakaryopoiesis

Question 33

What are the proginators for platelet production?

Answer 33

BFU-MEG and CFU-MEG

Question 34

What are the growth factors for megakaryopoiesis

Answer 34

IL-3 SCF IL-6 IL-11

Question 35

What growth factor is specific for CFU-MEG

Answer 35

Thrombopoietin (TPO)

Question 36

Where is TPO synthesized?

Answer 36

Liver

Question 37

Megakaryocyte precursors undergo \_\_\_\_\_? What is it?

Answer 37

Endomitosis Cell growth, DNA replication and nuclear division without cytoplasmic division

Question 38

What is the canalicular system in platelets?

Answer 38

A way for platelet contents to leave the cell to release activating factors, but without compromising the cell's integrity so it can continue to maintain shape and continue to be a part of clotting response

Question 39

Granulopoiesis Chart

Answer 39

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