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HDM (Sophia's) > Hematopoiesis > Flashcards

Hematopoiesis Flashcards

1
Q

Where/how does hematopoiesis begin in the fetus?

A

hemangioblasts –> hematopoietic islands in umbilical vesicle/yolk sac (1st trimester) –> liver and spleen (2nd trimester) –> bone marrow (7th month)

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2
Q

What is the overall makeup of bone marrow?

A

blood vessels
hematopoietic cells
sinusoids

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3
Q

What is a sinusoid?

A

vascular unit of BM

endothelial lining, discontinuous basement membrane, and incomplete covering of adventitial cells

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4
Q

What are adventitial cells?

A
  • incompletely surround sinusoids of bone marrow
  • provide support for developing blood cells
  • produce reticular fibers and secrete cytokines
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5
Q

where do hematopoietic cells lie in bone marrow?

A

in cords in btwn sinusoids

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6
Q

How do maturing blood cells enter a sinusoid to enter blood?

A

cells push against endothelial cell –> fuse and pierce luminal PM –> forms opening and squeezes through to sinusoidal lumen –> endothelial cell repairs itself

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7
Q

How do megakaryocytes enter the sinusoidal lumen?

A

too big for entire cell to go

proplatelets extend through –> blood flow breaks it into platelets in blood

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8
Q

Where is red bone marrow found?

A

in medullary cavity of young long bones

in flat bones in adults

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9
Q

What are the predominant cell types/products in red bone marrow?

A

hematopoietic cords are predominately making blood cells and megakaryocytes
(macrophages, mast cells, and some adipose cells are also present)

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10
Q

What is the predominant cell type of yellow bone marrow?

A

adipose cells (not very hematopoietically active)

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11
Q

In active bone marrow in an adult, what is the ratio of adipose to hematopoietic tissue?

A

50:50

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12
Q

How do you calculate the normal cellularity of a person’s bone marrow?

A

100 - person’s age + or - 10%

30 year old = 60-80% active cells

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13
Q

What is hypocellular marrow?

A

fewer blood-forming cells are found than expected

aplastic anemia, chemotherapy

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14
Q

What is hypercellular marrow?

A

more blood-forming cells than expected

usually because of tumors

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15
Q

What is the difference between a bone marrow aspirate and and bone marrow core biopsy?

A

In both, needle is inserted into bone marrow
in core biopsy: try to keep marrow architecture in tact; don’t do a smear; do rotating motion
in aspirate: spread as a smear, don’t have to rotate needle

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16
Q

What are the 3 major groups of hematopoietic growth factors?

A

colony-stimulating factors (CSF)
erythropoietin (EPO) and thrombopoietin (TPO)
interleukins (cytokines)

17
Q

What do HSCs give rise to immediately?

A

common myeloid progenitor (CMP) cells

OR: Common lymphoid progenitor (CLP) cells

18
Q

What do common myeloid progenitor cells give rise to?

A

MEP: megakaryocyte/erithrocyte progenitors
OR: GMP: granulocyte/monocyte progeniotrs

19
Q

what is erythropoiesis regulated by?

A

erythropoietin (EPO) = secreted in response to low O2; acts on surface receptors of the ErP
GATA-1 is required for terminal differentiation

20
Q

How would an MEP differentiate to the erythrocyte lineage?

A

EPO, IL-3, and IL-4 act on MEP –> to erythropoietin-sensitive erythrocyte-committed progenitor (ErP/CFU-E)
(GATA-1 required)

21
Q

What is the overall sequence of precursors to form an erythrocyte?

A

HSC –> Common myeloid precursor –> MEP –> ErP –> Proerythroblast –> basophilic erythroblast –> polychromatophilic erythroblast –> orthochromatophilic erythroblast (normoblast) –> polychromatophilic erythrocyte (reticulocyte) –> erythrocyte

22
Q

What characterizes a proerythroblast?

A

large cell
cytoplasm is basophilic
recognizable, but not easily identified

23
Q

What characterizes a basophilic erythroblast?

A

small nucleus
cytoplasm w/ strong basophilia
accumulation of Hb will gradually change staining

24
Q

What characterizes a polychromatophilic erythroblast?

A

acidic and basophilic staining

nucleus is smaller than basophilic erythroblast

25
Q

What characterizes an orthochromatophilic erythroblast/normoblast?

A

more acidophilic staining of cytoplasm and dense purple nucleus
no longer capable of division
will extrude nucleus and pass into sinusoids

26
Q

What characterizes a polychromatophilic erythrocyte/reticulocyte?

A

acidophilic staining
special stains highlight polyribosomes
1-2% of RBC count

27
Q

What is thrombopoiesis?

A

formation of thrombocytes/platelets

HDM (Sophia's) (10 decks)

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