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HOS Unit 3 > 1 Overview of Hematopoiesis > Flashcards

1 Overview of Hematopoiesis Flashcards

1
Q

When in the fetus (weeks or months) does hematopoiesis occur only in a yolk sac? liver and spleen? only bone marrow?

A
  • <6 weeks
  • 6 wks to 7 months
  • 7 months onward
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2
Q

In infancy, what bones have hematopoiesis?

A

All bones… then fatty replacement and hematopoiesis only in central skeleton

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3
Q

The production of blood cells outside of the marrow space?

A

extramedullary hematopoiesis-most common in fetal spleen and liver

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4
Q

What supplies oxygenated blood to marrow?

A

nutrient arteries and periosteal capillary network

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5
Q

How does blood leave marrow?

A

thin endothelial lined sinusoids

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6
Q

What borders sinusoids in marrow?

A

adventitial reticular cells

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7
Q

What regulates passage of hematopoietic cells into systemic circulation?

A

adventitial reticular cells

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8
Q

What direction does the sinusoids drain?

A

periphery to center of the marrow–emptying into central vein

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9
Q

What produces structural scaffolding for bone marrow extravascular compartment??

A

stromal cells- fat cells, macrophages, reticular cells, fibroblasts

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10
Q

t-f, T cells and macrophages cannot produce regulatory factors or cytokines in bone marrow?

A

false

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11
Q

Are most pluripotent, self renewal hematopoietic stem cells very active?

A

No-quiescent

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12
Q

Is differentiation reversible?

A

No

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13
Q

What do HSC express on surface and are identified by?

A

CD34

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14
Q

Is there a higher frequency than stems for the committed progenitor cells?

A

Yes–myeloid and lymphoid

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15
Q

What cells (or stage) are recognizable by microscopic examination of the marrow?

A

Late precursors and mature blood cells

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16
Q

Are hematopoietic growth factors soluble or membrane bound?

A

Both—most are cytokines

17
Q

What produces hematopoietic GFs?

A

stromal cells, endothelial cells, HEMATOPOIETIC STEM CELLS, fat cells, macrophages

18
Q

Glycoprotein c-kit ligand is important for?

A

proliferation, migration and adhesion of stem cells

19
Q

What type of ligand is FLT-3?

A

tyrosine kinase ligand

20
Q

IL-3 does what to myeloid progenitors?

A

stimulates proliferation….GM-CSF does this also

21
Q

What are the major pathways caused by dimerization of receptors in hematopoietic cells?

A

JAK/STAT
MAP
PI3

22
Q

What is the earliest committed erythroid precursor?

A

BFU-e (burst forming unit-erythroid)

23
Q

What stage comes after BFU-e stage?

A

CFU-e (colony forming unit-erythroid)

24
Q

What is the main important growth factor for erythroid cells? what is it produced by?

A

erythropoietin (EPO)

produced by peritubular kidney cells in response to hypoxia

25
Q

when is erthropoietin effective and what does it induce?

A

red cell production from BFU-e stage through maturation—about 25% of marrow cells are maturing red cells from the CFU-e onward stages

26
Q

What are the stages of hemoglobin accumulation?

A 
pronormoblast
basophilic normoblast
polychromatophilic normoblast
orthochromic normoblast
polychromatophilic red cell
erythrocyte
27
Q

How long do red cells live in circulation?

A

120 days

28
Q

What is the major growth factor for granulocytes?

A

GM-CSF and IL-3

29
Q

What does CFU-GM differentiate into?

A

CFU-G and CFU-M (GFs are G-CSF and M-CSF)

further maturation is caused by these same GFs until neutrophil and monocyte

30
Q

Myeloid maturation steps?

A

myeloblast>promyelocyte>myelocyte>metamyelocyte>band>segmented neutrophil

31
Q

What are dendritic cells, osteoclasts and macrophages derived from?

A

monocyte precursors

32
Q

What is thrombopoiesis?

A

production of platelets (megakaryopoiesis too)

33
Q

What are the progenitors for megakaryopoiesis?

A

BFU-MEG and CFU-MEG

GFs= IL-3, IL-6, IL-11, SCF

34
Q

What GF has specificity for CFU-MEG and maturing megakaryocytic and promotes proliferation and differentiation? where is it synthesized?

A

Thrombopoietin (TPO), LIVER

35
Q

What regulates production of thrombopoietin?

A

platelet mass and decreased platelet counts upregulate

36
Q

Are megakaryocytic found in large numbers in the bone marrow?

A

no

37
Q

What is cell growth, DNA replication and nuclear division without cytoplasmic division? example?

A

endomitosis-(megakaryocytes)

muliploid cells with nuclear content 8-32N

38
Q

What are cytoplasmic fragments of megakaryocytic?

A

platelets–live for 7-10 days

HOS Unit 3 (9 decks)

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