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Hema Readings Chapter 5&9 > Chapter 5 Erythrocyte Production and Destruction > Flashcards

Chapter 5 Erythrocyte Production and Destruction Flashcards

1
Q

has one true function: to carry oxygen from the lung to the tissues, where the oxygen is released. This is accomplished by the attachment of the oxygen to hemoglobin, the major cytoplasmic component of mature RBCs.

A

erythrocyte

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2
Q

unique among animal cells in that in its mature, functional state, it does not have a nucleus

A

mammalian erythrocyte

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3
Q

nucleated RBC precursors, normally restricted to the bone marrow, also may be called normoblasts

A

erythroblasts

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4
Q

developing nucleated RBC precursors (i.e., blasts) with normal appearance

A

normoblasts

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5
Q

morphologically identifiable erythrocyte precursors develop from two progenitors, burst-forming unit-erythroid (BFU-E) and colony-forming unit-erythroid (CFU-E), both committed to the erythroid cell line.

A

Erythroid Progenitors

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6
Q

These erythroid progenitors are named for their ability to form colonies on semisolid media in culture experiments that enable the study of their characteristics and development.

A

burst-forming unit-erythroid (BFU-E) and colony-forming unit-erythroid (CFU-E)

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7
Q

The earliest committed progenitor, gives rise to large colonies because they are capable of multisubunit colonies (called bursts)

A

BFU-E

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8
Q

gives rise to smaller colonies

A

CFU-E

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9
Q

it takes about 1 week for the BFU-E to mature to the CFU-E and another week for the CFU-E to become a pronormoblast

A

first morphologically identifiable RBC precursor

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10
Q

for the precursors to become mature enough to enter the circulation

A

it takes approximately another 6 to 7 days

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11
Q

required to produce a mature RBC from the BFU-E

A

approximately 18 to 21 days

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12
Q

similar to the proliferation of other cell lines, is a process encompassing replication (i.e., division)to increase cell numbers and development from immature to mature cell stages

A

Normoblastic proliferation

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13
Q

The earliest morphologically recognizable erythrocyte precursor

A

pronormoblast

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14
Q

derived via the BFU-E and CFU-E from pluripotent hematopoietic stem cells

A

pronormoblast

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15
Q

The pronormoblast is able to divide, with each daughter cell maturing to the next stage of development

A

basophilic normoblast

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16
Q

Each of these cells can divide, with each of its daughter cells maturing to the next stage. Each of these cells also can divide and mature

A

polychromatic normoblast

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17
Q

In the erythrocyte cell line, there are typically three and occasionally as many as five divisions with subsequent nuclear and cytoplasmic maturation of
the daughter cells; from a single pronormoblast, therefore

A

8 to 32 mature RBCs usually result

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18
Q

Morphologic identification of blood cells depends on a well-stained

A

peripheral blood film or bone marrow smear

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19
Q

In hematology, a modified Romanowsky
stain, is commonly used, such as

A

Wright or Wright-Giemsa

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20
Q

The stage of maturation of any blood cell is determined by careful examination of the

A

nucleus and the cytoplasm

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21
Q

The most important features in the identification of RBCs are the

A

nuclear chromatin pattern (texture, density, homogeneity),
nuclear diameter,
nucleus-to-cytoplasm (N:C) ratio,
presence or absence of nucleoli, and
cytoplasmic color

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22
Q

As erythroid precursors mature, several general trends affect their appearance, graphically represents these trends.

A
  1. Overall diameter of the cell decreases.
  2. Diameter of the nucleus decreases, the N:C ratio also decreases
  3. Nuclear chromatin pattern becomes coarser, clumped, and condensed.
  4. Nucleoli disappear.
  5. Cytoplasm changes from blue to gray-blue to salmon pink.
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23
Q

The nuclear chromatin of erythroid precursors
is inherently coarser than that of myeloid precursors. It becomes even coarser and more clumped as the cell matures, developing a

A

raspberry-like appearance

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24
Q

Ultimately the nucleus becomes quite condensed,
with no parachromatin evident at all, and the nucleus is said to be

A

pyknotic

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25
Q

morphologic feature used to identify and stage red blood cell and white blood cell precursors. The ratio is a visual estimate of the area of the cell occupied by the nucleus compared with that of the cytoplasm

A

nucleus-to-cytoplasm (N:C) ratio

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26
Q

In the red blood cell line, the proportion of nucleus shrinks as the cell matures and the cytoplasm increases proportionately, although the overall cell diameter grows smaller

A

In short, the N:C ratio decreases.

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27
Q

nucleoli disappear, which precedes the ultimate cessation of protein synthesis

A

erythroid precursors mature

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28
Q

due to acidic components that attract basic stains, such as methylene blue

A

Blueness or basophilia

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29
Q

due to accumulation of more basic components that attract acid stains, such as eosin

A

Pinkness, called eosinophilia or acidophilia

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30
Q

the cell starts out being active in protein production on the ribosomes that make the

A

cytoplasm basophilic

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31
Q

gradual process, however, with changes occurring in a generally predictable sequence but with some variation for each individual cell

A

Cell maturation

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32
Q

Rubriblast

A

Pronormoblast

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33
Q

nucleus takes up much of the cell

A

(N:C ratio of 8:1)

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34
Q

round to oval, containing one or two nucleoli. The purple red chromatin is open and contains few, if any, fine clumps

A

Pronormoblast (Rubriblast): Nucleus

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35
Q

dark blue because of the concentration of ribosomes and RNA

A

Pronormoblast (Rubriblast): Cytoplasm

36
Q

may show small tufts of irregular cytoplasm along the periphery of the membrane

A

Pronormoblast (Rubriblast): Pronormoblast

37
Q

The pronormoblast undergoes mitosis and gives rise to two daughter pronormoblasts

A

Pronormoblast (Rubriblast): Division

38
Q

The pronormoblast is present only in the bone marrow in healthy states.

A

Pronormoblast (Rubriblast): Location

39
Q

The pronormoblast begins to accumulate the components necessary for hemoglobin production. The proteins and enzymes necessary for iron uptake and protoporphyrin synthesis are produced. Globin production begins.

A

Pronormoblast (Rubriblast): Cellular activity

40
Q

This stage lasts slightly more than 24 hours.

A

Pronormoblast (Rubriblast): Length of time in this stage

41
Q

Prorubricyte

A

Basophilic Normoblast

42
Q

Basophilic Normoblast (Prorubricyte) Nucleus

The chromatin begins to condense, revealing clumps
along the periphery of the nuclear membrane and a few in the interior. The parachromatin areas become larger and sharper. The chromatin stains deep purple-red.

A

N:C ratio decreases to about 6:1

43
Q

When stained, may be a deeper, richer blue than in the pronormoblast, hence the name basophilic for this stage.

A

Basophilic Normoblast (Prorubricyte): Cytoplasm

44
Q

The basophilic normoblast undergoes mitosis, giving rise to two daughter cells. More than one division is possible before the daughter cells mature into polychromatic normoblasts.

A

Basophilic Normoblast (Prorubricyte): Division

45
Q

The basophilic normoblast is present only in the
bone marrow in healthy states.

A

Basophilic Normoblast (Prorubricyte): Location

46
Q

Detectable hemoglobin synthesis occurs, but the many cytoplasmic organelles, including ribosomes and a substantial amount of messenger ribonucleic acid (mRNA; chiefly for hemoglobin production), completely mask the minute amount of hemoglobin pigmentation.

A

Basophilic Normoblast (Prorubricyte): Cellular activity

47
Q

This stage lasts slightly more than 24 hours.

A

Basophilic Normoblast (Prorubricyte): Length of time in this stage

48
Q

Polychromatic Normoblast

A

Polychromatophilic Rubricyte

49
Q

Polychromatic Normoblasts (Rubricytes): Nucleus

The condensation of chromatin reduces the diameter of the nucleus considerably. Notably, no nucleoli are present.

A

N:C ratio decreases from 4:1 to about 1:1 by the end of the stage

50
Q

This is the first stage in which the pink color associated with stained hemoglobin can be seen

A

Polychromatic Normoblasts (Rubricytes): Cytoplasm

51
Q

Polychromatic Normoblasts (Rubricytes): Cytoplasm

The stained color reflects the accumulation of hemoglobin pigmentation over time and concurrent decreasing amounts of RNA. The color produced is a mixture of pink and blue, resulting in a

A

murky gray-blue

52
Q

Polychromatic Normoblasts (Rubricytes): Cytoplasm

The stage’s name refers to this combination of multiple colors, because polychromatophilic means

A

“many color loving.”

53
Q

This is the last stage in which the cell is capable of
undergoing mitosis, although likely only early in the stage. Producing daughter cells that mature and develop into orthochromic normoblasts.

A

Polychromatic Normoblasts (Rubricytes): Division

54
Q

The polychromatic normoblast is present only in the bone marrow in healthy states.

A

Polychromatic Normoblasts (Rubricytes): Location

55
Q

Hemoglobin synthesis increases, and the accumulation begins to be visible as a pinkish color in the cytoplasm. Cellular RNA and organelles are still present, particularly ribosomes. The progressive condensation of the nucleus and disappearance of nucleoli are evidence of progressive decline in transcription of deoxyribonucleic acid (DNA).

A

Polychromatic Normoblasts (Rubricytes): Cellular activity

56
Q

This stage lasts approximately 30 hours.

A

Polychromatic Normoblasts (Rubricytes): Length of time in this stage

57
Q

Metarubricyte

A

Orthochromic Normoblast

58
Q

Orthochromic Normoblast (Metarubricyte): Nucleus

The nucleus is completely condensed (i.e., pyknotic) or nearly so. As a result, the

A

N:C ratio is low or approximately 1:2

59
Q

The increase in the salmon pink color of the cytoplasm reflects nearly complete hemoglobin production.

A

Orthochromic Normoblast (Metarubricyte): Cytoplasm

60
Q

The orthochromic normoblast is not capable of division because of the condensation of the chromatin.

A

Orthochromic Normoblast (Metarubricyte): Division

61
Q

Hemoglobin production continues on the remaining ribosomes using messenger RNA produced earlier.
Late in this stage, the nucleus is ejected from the cell. The nucleus moves to the cell membrane and into a pseudopod-like projection.

A

Orthochromic Normoblast (Metarubricyte): Cellular activity

62
Q

Orthochromic Normoblast (Metarubricyte): Cellular activity

As part of the maturation process, a protein responsible for holding organelles in proper location in the cytoplasm

A

loss of vimentin

63
Q

Orthochromic Normoblast (Metarubricyte): Cellular activity

Nonmuscle myosin of the membrane is important in this pinching process.6 The enveloped extruded nucleus, called
is then engulfed by bone marrow macrophages.

A

pyrenocyte

64
Q

Orthochromic Normoblast (Metarubricyte): Cellular activity

The macrophages recognize phosphatidylserine on the pyrenocyte surface as an

A

“eat me” flag

65
Q

Orthochromic Normoblast (Metarubricyte): Cellular activity

Often, small fragments of nucleus are left behind if the projection is pinched off before the entire nucleus is enveloped. These fragments are called

when seen in peripheral RBCs and are typically removed from the cells by the splenic macrophage pitting process once the cell enters the circulation.

A

Howell-Jolly bodies

66
Q

This stage lasts approximately 48 hours.

A

Orthochromic Normoblast (Metarubricyte): Length of time in this stage

67
Q

Polychromatic (Polychromatophilic) Erythrocyte or

A

Reticulocyte

68
Q

There is no nucleus, when a cell loses its nucleus,
regardless of cytoplasmic appearance, it is a polychromatic erythrocyte.

A

Reticulocyte: Nucleus

69
Q

Hemoglobin yet with a bluish tinge due to some residual ribosomes and RNA. By the end of the polychromatic erythrocyte stage, the cell is the same color as a mature RBC, salmon pink. It remains larger than a mature cell, however. The shape of the cell
is not the mature biconcave disc but is irregular in electron micrographs

A

Reticulocyte: Cytoplasm

70
Q

Lacking a nucleus, the polychromatic erythrocyte cannot divide

A

Reticulocyte: Division

70
Q

The polychromatic erythrocyte resides in the bone marrow for about 1 to 2 days and then moves into the peripheral blood for about 1 day before reaching maturity

A

Reticulocyte: Location

71
Q

Reticulocyte: Location

The polychromatic erythrocyte is retained in the spleen for pitting of inclusions and membrane polishing by splenic macrophages, which results in the

A

biconcave discoid mature RBC

72
Q

Reticulocyte: Cellular activity

The cytoplasmic protein production machinery is simultaneously being dismantled, digests the ribosomes.

A

Endoribonuclease

73
Q

Reticulocyte: Cellular activity

The residual ribosomes appear as a mesh of small blue strands, a reticulum, or, when more fully digested, merely blue dots. When so stained, the polychromatic erythrocyte is called

However, the name reticulocyte is often used to refer
to the stage immediately preceding the mature erythrocyte even when stained with Wright stain and without demonstrating the reticulum.

A

reticulocyte

74
Q

The cell typically remains a polychromatic erythrocyte for about 3 days,4 with the first 2 days spent in the bone marrow and the third spent in the peripheral blood, although possibly sequestered in the spleen.

A

Reticulocyte: Length of time in this stage

75
Q

Mature Erythrocytes or

A

Erythrocyte

76
Q

No nucleus is present in mature RBCs.

A

Erythrocyte: Nucleus

77
Q

Erythrocyte: Cytoplasm

The mature circulating erythrocyte is a biconcave disc measuring, with a thickness of about

A

7 to 8 “m in diameter
1.5 to 2.5 “m.

78
Q

On a Wright-stained blood film, it appears as a salmon-pink stained cell with a central pale area that corresponds to the concavity. The central pallor is about one-third the diameter of the cell.

A

Erythrocyte: Cytoplasm

79
Q

The erythrocyte cannot divide.

A

Erythrocyte: Division

80
Q

Mature RBCs remain active in the circulation for approximately 120 days.

A

Erythrocyte: Location and length of time in this stage.

81
Q

The mature erythrocyte delivers oxygen to tissues, releases it, and returns to the lung to be reoxygenated.

A

Erythrocyte: Cellular activity

82
Q

Erythrocyte: Cellular activity

contains mostly hemoglobin, the oxygen-carrying component. It has a surface area-to-volume ratio and shape that enable optimal gas exchange to occur.

A

interior of the erythrocyte

83
Q

The cell’s main function of oxygen delivery throughout the body requires a membrane that is

A

flexible and deformable, that is, able to flex but return to its original shape

84
Q

RBCs must squeeze through small spaces such as the

A

basement membrane of the bone marrow venous
sinus.

85
Q

when a cell enters the red pulp of the spleen, it must squeeze between epithelial cells to move into the

A

venous outflow

86
Q

crucial for RBCs to enter and subsequently remain in the circulation

A

Deformability

Hema Readings Chapter 5&9 (9 decks)

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