Hematopoiesis

Question 1

Monophyletic theory

Answer 1

All blood cells are derived from a single, pluripotent hemopoietic stem cell.

Question 2

Where does hematopoiesis occur in the fetus in the 1st trimester?

Answer 2

Hematopoietic islands of hematopoiesis in umbilical vesicle.

Question 3

Hematopoietic islands develop from:

Answer 3

Hemangioblasts, which are progenitors of hematopoietic and endothelial cells.

Question 4

Hematopoiesis timeline in fetal development:

Answer 4

Starts in the 1st trimester in the hematopoietic islands.
Continues in 2nd trimester in the liver & spleen.
After 7 mo., the bone marrow becomes primary site of hematopoiesis.

Question 5

Sinusoids

Answer 5

Found in BM.

Discontinuous capillaries w/ incomplete covering of adventitial cells.

Question 6

Adventitial cells

Answer 6

Provides blood support for developing blood cells.

Produce reticular fibers and release cytokines.

Question 7

Bone marrow-sinusoidal system

Answer 7

Maturing blood cells pushes against the endothelial wall and fuses through the endothelial cell and a create small aperture. Each cell squeezes through this opening and enters the sinusoidal lumen.
The endothelial cell repairs itself and aperture disappears.

Question 8

Red bone marrow

Answer 8

Common in young long bones and in spongy bone.

Generally includes developing blood cells, megakryocytes, Mo, MCs, and some adipose.

Question 9

Erythroblasts and megakaryocytes develop in:

Answer 9

Nests near the sinusoidal wall in red bone marrow.

Question 10

Granulocytes develop in:

Answer 10

Nests further from sinsoidal wall in red bone marrow.

Question 11

How do you determine the cellularity of bone marrow?

Answer 11

Subtract person’s age from 100 and add +/- 10 to create range.
ex: 30 y/o = 60-80% active cells.

Question 12

Bone marrow aspirate protocol

Answer 12

Needle inserted thru skin and into bone (preferably posterior iliac crest) and spread as a smear to evaluate.

Question 13

Bone marrow core biopsy protocol

Answer 13

Needle inserted into bone to get intact bone marrow. Needle is rotated to create a “core” and retrieve a solid sample of bone marrow.
Allows analysis of bone marrow architecture.

Question 14

Hematopoiesis occurs in bone barrow of what bones? (6)

Answer 14

Skull
Ribs
Sternum
Vertebrae
Pelvis
Femur

Question 15

3 major groups of hematopoietic growth factors:

Answer 15

Colony-stimulating factors (CSF)
Erythopoietic and thrombopoietin (EPO. TPO)
Interleukins (cytokines)

Question 16

IL-3

Answer 16

Influences growth and replication of hematopoietic progenitors.

Question 17

IL-2

Answer 17

T cell growth factor.

Question 18

IL-1 and IL-4

Answer 18

Acts on pluripotent SCs to develop lymphoid SCs.

Question 19

Thrombopoietin

Answer 19

Stimulates increase of megakaryocytes and platelets.

Produced in liver.

Question 20

Granulocyte-macrophage colony-stimulating factor (GM-CSF)

Answer 20

Stimulates formation of leukocytes and reticulocytes.

Question 21

Granulocyte colony-stimulating factor (G-CSF)

Answer 21

Stimulates increase in neutrophils.

Question 22

Macrophage colony-stimulating factor (M-CSF)

Answer 22

Stimulates increase in monocytes and Mo.

Question 23

Multipotent progenitor blood cells (2)

Answer 23

Common myeloid progenitor (CMP)

Common lymphoid progenitor (CLP)

Question 24

CMP gives rise to:

Answer 24

MEP: megakaryocytes, erythrocyte progenitors.
GMP: N, E, B, Monocyte progenitors.

Question 25

Yellow bone marrow

Answer 25

Mostly adipose. Found in bone marrow of adults that are not hematopoietically active. Can potentially revert to RBM.

Question 26

Adult bone marrow is how much adipose and how much hematopoietic tissue?

Answer 26

50:50

Question 27

Erythropoiesis regulated by:

Answer 27

EPO, which is released by the kidney in response to low O2.

Question 28

GATA-1

Answer 28

Protein required for terminal differentiation of erythroid lineage.

Question 29

Process of developin an erythrocyte (6)

Answer 29

``` Proerythroblast Basophilic erythroblast Polychromatophilic erythroblast Orthochromatic erythroblast Reticulocyte Erythrocyte ```

Question 30

What growth factors induce MEP differentiation? (2)

Answer 30

GM-CSF | IL-3

Question 31

Megakaryocyte and platelet formation steps (3)

Answer 31

1. TPO is produced in liver and kidney --> stimulates megakaryocyte production. 2. Platelets fill peripheral cytoplasm of megakaryocyte. 3. Platelets broken off into sinusoids.

Question 32

What growth factors stimulate GMP differentiation? (2)

Answer 32

GM-CSF | IL-3

Question 33

Myeloblast

Answer 33

Earliest neutrophil precursor. Large nucleus. Very basophilic. Matures to promyelocyte.

Question 34

Promyelocyte

Answer 34

Large nucleus w/ primary granules. Granules get smaller with each division. No subtypes.

Question 35

Myelocyte

Answer 35

First to exhibit specific granules. | Spherical nucleus.

Question 36

Metamyelocyte

Answer 36

Nuclear indentation deepens. Specific granules outnumber azurophilic granules. Give rise to banded cells.

Question 37

Granulopoiesis steps (4)

Answer 37

1. Myeloblast 2. Promyelocyte 3. Myelocyte 4. Metamyelocyte

Question 38

Immature neutrophils enter a:

Answer 38

Reserve pool in bone marrow for 5 days.

Question 39

From the reserve pool:

Answer 39

50% of band forms circulate. 50% will adhere to endothelial walls (marginalized pool) Both can be used upon demand.

Question 40

Development of a monocyte (3)

Answer 40

1. Monocyte progenitor cell (very similar ro myeloblast morphologically) 2. Promonocyte 3. Monocyte Takes about 55 hrs.