Erythrocyte

Erythrocytes, also known as red blood cells, are the most common type of blood cell and the principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system. They take up oxygen in the lungs and release it while passing through the body's capillaries.

Structure

Erythrocytes are biconcave discs, flattened and depressed in the center, with a diameter of about 6–8 micrometers. They have a flexible structure and can change shape to an extent. Unlike cells of other types, mature erythrocytes cannot divide or replicate. Also, they lack a nucleus and most organelles, in order to accommodate maximum space for hemoglobin.

Function

The primary function of erythrocytes is to transport oxygen from the lungs to all the body tissues, and carbon dioxide as a waste product away from the tissues and back to the lungs. Hemoglobin, an iron-containing protein inside red blood cells, facilitates the transport of oxygen and carbon dioxide.

Production and lifespan

Erythrocytes are produced in the bone marrow in a process called erythropoiesis. The production is regulated by the hormone erythropoietin, which is produced primarily by the kidneys. The average lifespan of an erythrocyte is 120 days.

Disorders

There are several disorders that affect the erythrocytes, including anemia, in which the body does not have enough red blood cells or the cells do not function properly, and polycythemia, a condition characterized by an excess of red blood cells.

See also

• Hemoglobin
• Anemia
• Polycythemia
• Erythropoiesis
• Bone marrow

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