Erythrocyte Production and Destruction Flashcards
The________ has one true function: to carry oxygen from the lung to the tissues, where the oxygen is re-leased.
This is accomplished by the attachment of the oxygen to______, the major cytoplasmic component of mature RBCs.
The role of the RBC in returning_____ to the lungs and_____ the pH of the blood is important but is quite secondary to its oxygen-carrying function.
erythrocyte
hemoglobin
carbon dioxide
buffering
The mammalian erythrocyte is unique among animal cells in that in its mature, functional state, it does not have a______.
nucleus
Although amphibians and birds possess RBCs, their nonmam-malian RBCs retain the_____ throughout the cells’ lives. The implications of this unique mammalian adaptation are significant for cell function and life span.
nuclei
RBCs are formally called_______. Nucleated RBC precursors, normally restricted to the bone marrow, are called_______.
They also may be called______, which refers to developing nucleated RBC precursors (i.e., blasts) with normal appearance.
erythrocytes
erythro-blasts
normoblasts
Three nomenclatures are used for naming erythroid precursors.
The______ terminology is commonly used in the United States and is descriptive of the appearance of the cells.
Some prefer the______ terminology because it parallels the nomenclature used for granulocyte development.
The_______ terminology is used primarily in Europe.
normoblastic
rubriblast
erythroblast
Erythroid Progenitors
The morphologically identifiable erythrocyte precursors develop from two progenitors,______ and _______, both committed to the erythroid cell line.
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.
burst-forming unit-erythroid BFU-E) and colony-forming unit-erythroid (CFU-E)
The earliest committed progenitor,_______, gives rise to large colonies because they are capable of multisubunit colonies (called bursts), whereas______ gives rise to smaller colonies.
BFU-E
CFU-E
Estimates of time spent at each stage suggest that it takes about_______ for the BFU-E to mature to the CFU-E and another week for the CFU-E to become a_______, which is the first morphologically identifiable RBC precursor.
While at the CFU-E stage, the cell completes approximately______ divisions before maturing further.
As seen later, it takes approximately another ______for the precursors to become mature enough to enter the circulation, so approximately ______days are required to produce a mature RBC from the BFU-E.
1 week
pronormoblast
three to five
6 to 7 days
18 to 21
Erythroid Precursors
________proliferation, 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.
Normoblastic
The earliest morphologically recognizable erythrocyte precursor, the________, is derived via the BFU-E and CFU-E from pluripotent hematopoietic stem cells.
It is able to divide, with each daughter cell maturing to the next stage of development, the______
Each of these cells can divide, with each of its daughter cells maturing to the next stage, the_______
Each of these cells also can divide and mature.
pronormoblast
basophilic normoblast
polychromatic normoblast.
In the erythrocyte cell line, there are typically______ and occasionally as many as_____ divisions’ with subsequent nuclear and cytoplasmic maturation of the daughter cells;
from a single pronormoblast, therefore,_____ to ____ mature RBCs usually result.
The changes and cellular activities at each stage described here occur in an orderly and sequential erythroid developmental process.
three/ five
8 to 32
Normoblastic
Pronormoblast
Basophilic normoblast
Polychromatic normoblast
Orthochromic normoblast
Polychromatic erythrocyte
Erythrocyte
Rubriblastic
Rubriblast
Prorubricyte
Rubricyte
Metarubricyte
Polychromatic erythrocyte
Erythrocyte
Erythroblastic
Proerythroblast
Basophilic erythroblast
Polychromatic erythroblast
Orthochromic ervthroblast
Polychromatic erythrocyte
Erythrocyte
Morphologic identification of blood cells depends on a well-stained peripheral blood film or bone marrow smear . In hematology, a_______ stain, such as_____ or _______, is commonly used.
modified Romanowsky
Wright or Wright-Giemsa
The stage of maturation of any blood cell is determined by careful examination of the _____ and _____
The most important features in the identification of RBCs are the_______ (texture, density, homogeneity),______,_______, presence or absence of_____, and_____ color.
nucleus and the cytoplasm.
nuclear chromatin pattern
nuclear diameter
nucleus-to-cytoplasm (N:C) ratio
nucleoli
cytoplasmic
As erythroid precursors mature, several general trends affect their appearance.
- Overall diameter of the cell decreases.
- Diameter of the nucleus decreases more rapidly than does the diameter of the cell. As a result, the N:C ratio also decreases.
- Nuclear chromatin pattern becomes coarser, clumped, and condensed.
- Nucleoli disappear.
- Cytoplasm changes from blue to gray-blue to salmon pink.
The nuclear chromatin of erythroid precursors is inherently coarser than that of_______ precursors.
It becomes even coarser and more clumped as the cell matures, developing a_____-like appearance, in which the dark staining of the chromatin is distinct from the almost white appearance of the parachromatin.
This chromatin/ parachromatin distinction is more dramatic than in other cell lines.
Ultimately the nucleus becomes quite condensed, with no parachromatin evident at all, and the nucleus is said to be______.
myeloid
raspberry
pyknotic
The________ is a 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.
If the areas of each are approximately equal, the N:C ratio is 1:1. Although not mathematically proper, it is common for ratios other than 1:1 to be referred to as if they were fractions.
If the nucleus takes up less than 50% of the area of the cell, the proportion of nucleus is lower and the ratio is lower (e.g., 1:5 or less than 1).
If the nucleus takes up more than 50% of the area of the cell, the ratio is higher (e.g., 3:1 or 3). 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.
In short, the
N:C ratio decreases.
nucleus-to-cytoplasm (N:C) ratio
_______represent areas where the ribosomes are formed and are seen early in cell development as cells begin actively synthesizing proteins.
As erythroid precursors mature, it disappear, which precedes the ultimate cessation of______.
Nucleoli
protein synthesis
________is due to acidic components that attract basic stains, such as methylene blue. The degree of cytoplasmic basophilia correlates with the amount of______
Blueness or basophilia
ribosomal RNA
The ribosomes and other organelles decline over the life of the developing erythroid precursor, and the blueness fades. Pinkness, called eosinophilia or acidophilia, is due to accumulation of more basic components that attract acid stains, such as______.
eosin
Eosinophilia of erythrocyte cytoplasm correlates with the accumulation of_______ as the cell matures.
Thus the cell starts out being active in_____ production on the ribosomes that make the cytoplasm basophilic, transitions through a period in which the red of_____ begins to mix with that blue, and ultimately ends with a thoroughly _______when the ribosomes are gone and only hemoglobin remains.
hemoglobin
protein
hemoglobin
salmon pink color
General Trends Affecting the Morphology of Erythroid Precursors During the Developmental Process.
(A), Cell diameter_____ and cytoplasm changes from_____ to ____.
(B), Nuclear diameter_____ and color changes from_____ to _____.
(C), Nuclear chromatin becomes ________.
(D), Composite of changes during the developmental process
decreases; blue to salmon pink
decreases; purplish-red to a very dark purple-blue
coarser, clumped, and condensed
Nucleus.
The nucleus takes up much of the cell (N:C ratio of 8:1).
The nucleus is round to oval, containing one or two nucleoli.
The purple red chromatin is open and contains few, if any, fine clumps.
Pronormoblast (Rubriblast)
Cytoplasm.
The cytoplasm is dark blue because of the concentration of ribosomes and RNA.
The Golgi complex may be visible next to the nucleus as a pale, unstained area.
It may show small tufts of irregular cytoplasm along the periphery of the membrane.
Pronormoblast (Rubriblast)
The ________ undergoes mitosis and gives rise to two daughter pronormoblasts.
More than one division is possible before maturation into basophilic normoblasts.
Pronormoblast (Rubriblast)
Location. The pronormoblast is present only in the _____in healthy states.
bone marrow
Cellular activity.
The______ begins to accumulate the components necessary for hemoglobin production.
pronormoblast
