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Rodak's Hematology > Erythrocyte Production and Destruction > Flashcards

Erythrocyte Production and Destruction Flashcards

1
Q

What is the major cytoplasmic component of RBCs

and what is it’s function ?

A
  • Hemoglobin
  • helps erythrocytes carry oxygen (via binding O2) to tissues
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2
Q

What is the fundamental definition of

anemia ?

A
  • diminished oxygen carrying capacity of the blood
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3
Q

What is another name for polychromatophilic erythrocytes ?

A
  • these are reticulocytes
    • when viewed using supravital stains
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4
Q

What is the difference between an erythroblast and erythrocyte?

A
  • erythroblasts are confined to the bone marrow
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5
Q

How long does it take for an erythroid to mature

and enter circulation ?

A
  • 18-21 days
  • there are usually 3-5 cell divisions of the pronormoblast to maturation
    • from one pronormoblasts 8-32 mature RBCs result
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6
Q

What does cytoplasmic basophilia correlate with in the RBC ?

A
  • amount of ribosomal RNA present
    • more basophilic = more RNA
  • eosinophilia
    • correlates with the amount of hemoglobin in the cytoplasm
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7
Q

What is the last stage of erythroid development

that the cell may undergo mitosis ?

A
  • polychromatophilic normoblast
  • also the first stage where the pink color associated with hemoglobin is seen
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8
Q

Which stage of erythrocyte maturation is the nucleus

condensed in the RBC ?

A
  • orthochromatic normoblast
  • nucleus is almost pyknotic
    • not capable of division
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9
Q

At which normoblast stage is hemoglobin

synthesis first detected?

A
  • basophilic normoblast
  • pronormoblast starts gathering all proteins necessary for hemoglobin synthesis
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10
Q

How long does a reticulocyte remain so, before

maturing to a mature RBC ?

A
  • 3 days
    • 2 days in the bone marrow
    • 1 day in the peripheral blood
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11
Q

What is the normal amount an RBC

remains in the peripheral blood?

A
  • 120 days
  • old RBCs are removed by the spleen
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12
Q

RBC morphology

review pgs. 66-70

A
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13
Q

In a mature erythrocyte

what is the amount of central pallor usually seen ?

A
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14
Q

What is the difference between the erythron

and RBC mass ?

A
  • Erythron:
    • the name given to the entire collection of erythrocytes within the body at all stages
    • includes those even within the spleen pending removal
  • RBC Mass:
    • only the cells in circulation
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15
Q

What is the body’s main system for sensing low oxygen ?

A
  • peritubular fibroblasts of the kidney
  • the kidney then produces Erythropoietin
    • major stimulatory cytokine for RBC production
    • under normal circumstances the amount of EPO production varies very little
    • normal amount replaces approximately the 1% of RBCs that are destroyed every day
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16
Q

What is erythropoietin ?

A
  • EPO is a true hormone
    • produced in the kidney and acts in the bone marrow
    • it is a growth factor/cytokine
17
Q

When EPO binds to its receptor on immature

RBCs what does it produce?

A
  • leads to increased cell division and maturation
  • increased intestinal iron absorption and hemoglobin synthesis
  • increased number of RBCs entering the circulation

This physiological response is caused by hypoxia-inducible factors (HIFs)

  • these result in gene expression changes leading to erythropoiesis
18
Q

Ultimately, what is the response of

increased EPO production ?

A
  • allows early release of reticulocytes from the bone marrow
  • prevents apoptotic death
  • reduces the time needed for cells to mature in the bone marrow

EPO can increase up to 1000 fold if necessary

19
Q

Why does a fetus/newborn have increased

concentrations of hemoglobin and RBCs ?

A
  • in utero there is a physiologic hypoxia
  • HgF is an adaptation to this
    • has a higher affinity for oxygen and less readily releases oxygen to the tissues
    • as compared to adult HgA
  • to compensate for the hypoxia created by HgF
    • more RBCs are produced
20
Q

How is erythropoietin measured ?

A
  • performed on plasma or other body fluids (urine)
  • typical normal levels:
    • 10-30 U/L sufficient for steady state
  • measured by chemiluminiscence
21
Q

Review bone marrow microenvironment

p. 73-74

A
22
Q

How do RBCs produce energy?

A
  • they lack mitochondria
  • produce ATP via glycolysis
    • the loss of these glycolytic enzymes is part of the process of cellular aging or senescence
    • when this occur the RBCs are destroyed by macrophages

Rodak's Hematology (5 decks)

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