Bone Marrow and Hemopoiesis Flashcards

1
Q

vascular sinusoids

A
  • “capillaries” of bones.. located between arterioles and venules
  • lined by endothelium with basal lamina
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2
Q

reticular cell in bone marrow

A

The precursor for lymphocyte and monocyte formation
-phagocytic cells that line the sinusoid
-cell on outer “adventitia”
extend sheet like processes and reticular fibers into hemopoietic compartments to help organize cells
-newly formed blood cells displace the reticular cells and basal lamina and pass into the sinusoid lumen

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3
Q

hemopoietic compartment of red marrow

A

lie between sinusoids or between the bone and sinusoids

-contain developing blood cells, mature blood cells, megakaryocytes, macrophages, mast cells and adipocytes

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4
Q

yellow marrow

A

adipocytes replace the hemopoietic tissue (predominates in adults but can revert to hemopoiesis if necessary)

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5
Q

Hemopoiesis

A

-formation of RBC, WBC, and platelets (thrombopoiesis)

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6
Q

what are all formed elements of blood derived from

A
  • pluripotent stem cell with CD34 surface marker. which gives rise to either multipotential LYMPHOID stem cell (CFU-L) or multipotential MYELOID stem cell (CFU-GEMM)
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7
Q

myeloid lineage

A

erythroid (CFU-E), neutrophil/monocyte (CFU-GM), eosinophil (CFU-Eo), basophil (CFU-Ba) and megakaryocyte (CFU-Meg)

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8
Q

Lymphoid lineage

A

DISTINCT CFU for T and B cells

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9
Q

erythropoiesis (general trends)

A
  • regulated by erythropoietin (released from kidney) in response to low oxygen concentration in blood
    1. cells go from a large precurser to small RBC
    2. cytoplasm goes from basophilic to eosinophlic
    3. chromatin becomes progressively denser until the pyknotic nucleus is finally extruded
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10
Q

phases of erythropoiesis

A
  1. pronormoblast: basophlic nucleus/cytoplasm
  2. basophilic normoblast: more basophilic nucleus/cytoplasm
  3. polychromatophilic normoblast: checkerboard nucleus, less basophilic cytoplasm. LAST STAGE FOR MITOSIS
  4. orthochromatophilic normoblast: pyknotic (super dense) nucleus. STAGE WHEN NUCLEUS IS GOING TO GET EXTRUDED, more eosinophilic cytoplasm
  5. Reticulocyte: immature RBC (has eER and ribosomes, but not nucleus) STAINED WITH AZURE II
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11
Q

Granulopoeises controlled by

A
  1. colony stimulating factors (CSFs) secreted by T-cells + others
  2. interleukin IL-3 secreted by T-cells
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12
Q

stages of granulopoeisis (PMN production?)

A

even though the granulocytes are derived from different colonies, they still follow similar stages

  1. myeloblast: lots of nucleoli, basophilic cytoplasm (less than pronormoblast), no granules present
  2. promyelocyte: elliptical nucleus, nonspecific granules present, more cytoplasm
  3. Myelocyte: chromatin begins to condense, nucleus flattens on one side, specific granule production LAST STAGE OF MITOTIC ACTIVITY
  4. Metamyelocytes: chromatin continues to condense, nucleus is bean shaped, more specific granules
  5. Band form: elongated nucleus, folded but unsegmented
  6. Segmented neurtophil = final product
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13
Q

Thrombopoiesis

A

regulated by thrombopoietin generated by kidney and liver, GM-CSF, and interleukins

  1. megakaryoblast
  2. megakaryocyte
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14
Q

Granulopoiesis general trends

A
  1. large to small cell
  2. round nucleus to lobated
  3. decreased cytoplasmic basophilia
  4. production of azurophils (nonspecific granules) comes before specific granule production
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15
Q

megakaryoblast

A

about 3x an RBC

  • nonlobed nucleus, basophilic cytoplasm
  • cell undergoes endomitosis
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16
Q

endomitosis

A

chromosomes are doubled but there is no karyokinesis or cytokinesis
-each replication causes nuclear location and increased size of the cell

17
Q

megakaryocyte

A

multilobed/infolded nucleus, granular cytoplasm (formation of platelet fields and release platelets directly into sinusoid lumen)

18
Q

thrombopoeisis general

A
small megakaryocyte (initial lobation of nucleus).. cytoplasm is becoming less prominent. with progression, nucleus is lost. 
platelets = broken bits of material from a megakaryocyte