erythrocyte


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erythrocyte

(ĭrĭth`rəsīt'): see bloodblood,
fluid pumped by the heart that circulates throughout the body via the arteries, veins, and capillaries (see circulatory system; heart). An adult male of average size normally has about 6 quarts (5.6 liters) of blood.
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Erythrocyte

 

a red blood corpuscle, or cell, in man, the vertebrates, and some invertebrates (echinoderms). Erythrocytes transport oxygen from the lungs to the tissues, and carbon dioxide from the tissues to the lungs. They regulate the acid-base balance and maintain osmotic balance in the blood and tissues. In addition, amino acids and lipids are absorbed from the blood plasma, and transported to the tissues, by erythrocytes.

Mature mammalian and human erythrocytes lack the nucleus that is present in the early stages of their development—that is, in the erythroblasts. They have the shape of a biconcave disk. Erythrocytes consist mainly of the respiratory pigment hemoglobin, which is responsible for the red color of blood. The erythrocytes of birds, reptiles, amphibians, and fishes are nucleated. The erythroblasts’ actively functioning nuclei gradually become inactive in the course of the erythrocytes’ development; they can, however, be reactivated. At the same time, ribosomes and other constituents that participate in protein synthesis disappear from the cytoplasm. The cell (or plasma) membrane plays an important role by permitting the passage of gases, ions, and water in the erythrocytes. On the surface of the lipoprotein membrane are specific glycoprotein antigens, or agglutinogens—the blood group factors responsible for the agglutination of erythrocytes.

The efficient functioning of hemoglobin depends on the erythrocytes’ area of surface contact with the environment. The smaller the erythrocytes, the greater their total surface area. The lower invertebrates have large erythrocytes (measuring, for example, 70 micrometers in diameter in the caudate amphibian Amphiuma), and the higher vertebrates have smaller ones (4 micrometers in diameter in goats). Human erythrocytes vary in diameter from 7.2 to 7.5 micrometers.

The number of erythrocytes in the blood normally remains constant, ranging from 4.5 to 5 million in 1 mm3 of human blood. The life-span of a human erythrocyte averages 125 days; approximately 2.5 million erythrocytes are formed and an equal number are destroyed every second. The total number decreases in anemia and increases in polycythemia. In the anemias, erythrocytes are found to change shape and size; they may be large (such as the megalocytes in Addison-Biermer anemia) or small, and they may, for example, be oval in shape (as in hemolytic anemia).

K. G. GAZARIAN and A. N. SMIRNOV

erythrocyte

[ə′rith·rə‚sīt]
(histology)
A type of blood cell that contains a nucleus in all vertebrates but humans and that has hemoglobin in the cytoplasm. Also known as red blood cell.

erythrocyte

a blood cell of vertebrates that transports oxygen and carbon dioxide, combined with the red pigment haemoglobin, to and from the tissues
References in periodicals archive ?
The activity of the erythrocyte PMRS was measured by the reduction of ferricyanide the method are described earlier [17].
The results show that all the three Porphyrin compounds caused an increase in the activity of erythrocyte Na+, K+-ATPase (Table-I).
It is necessary to consider the described changes to phospholipid structure of erythrocyte membranes in the surveyed patients in terms of mechanisms of the lipid turnover in erythrocyte membrane, where the basis for the acylation reaction include specific enzyme acetyltransferase, magnesium, and adenosine triphosphate (ATP).
Our results show that the CPZ is able to cross the erythrocyte membrane, but probably because of its peculiar chemical structure, it intercalates abundantly in the phospholipid bilayer.
Impairment of erythrocyte viscoelasticity is correlated with levels of glycosylated haemoglobin in diabetic p atients.
The effect of ceftriaxone on plasma, erythrocyte and tissue TBARS levels in mice are presented in Table 1.
Erythrocyte Parameters Assay: Red blood cell (RBC) counts, haemoglobin content (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) and distribution frequency of red blood cell (RDWC) were determined using rat mode of veterinary blood cell counter (Abocus Junior Vet-5, Austria) in whole blood.
It was observed that value of total erythrocytes count and hemoglobin concentration was found to be significantly higher in case of male (5.05 +- 0.5 x 106 and 11.5.0% and 4.04 +- 0.5 x 106 and 7.0%) then female.
Impaired cytoadherence of Plasmodium falciparum-infected erythrocytes containing sickle hemoglobin.
Regarding blood cell counts, there was a borderline decrease in the erythrocyte count and a significant increase in the reticulocyte index in the EOPE group when compared to the C group.
Neutrophil and erythrocyte morphological changes observed as EDTA sample ages at room temperature.