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(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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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).



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.


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 ?
In this condition, the erythrocyte membrane loses its stabilization and a chronic non-spherocytic anemia develops.
Effects of cold water swimming on blood rheological properties and composition of fatty acids in erythrocyte membranes of untrained older rats.
2+] permeable erythrocyte cation channels is still illdefined but presumably involves the transient receptor potential channel TRPC6 (Foller et al.
In as little as one day after the venipuncture, the sample collected in EDTA and kept at room temperature began to show significant degenerative changes in leukocyte and erythrocyte morphology.
24) The counts of erythrocyte, leucocyte, and platelet along with total hemoglobin content, which were depleted due to arsenic insult showed to be prevented on ALA supplementation.
The effect of mild diamide oxidation on the structure and function of human erythrocyte spectrin.
Erythrocyte micronuclei in Winter flounder (Pseudopleuronectes americanus): results of fields surveys during 1980-1988 from Virginia to Nova Scotia and in long Island sound.
Erythrocyte GSH was measured following the method of Beutler (1984) [15].
Collection of blood samples and isolation of erythrocyte membranes: Blood samples were obtained from 15 volunteers.
Blood in the EDTA tubes was used to determine haemoglobin (Hb) concentration, erythrocyte count and red cell indices by Haematology Analyser Sysmex KX -21.