Red blood cells flowing

Red blood cells, or erythrocytes, are the blood cells responsible for transporting oxygen from the lungs to all tissues in the human body.

About this subject

Red blood cells, also called erythrocytes, are the most abundant cells in human blood. A healthy adult typically has between 4.5 and 5.5 million red blood cells per microliter of blood. Their biconcave disc shape, lacking a nucleus in the mature stage, maximizes surface area for gas exchange and provides flexibility to squeeze through narrow capillaries.

The primary function of red blood cells is to transport oxygen from the lungs to tissues and to carry away some carbon dioxide. This is achieved by hemoglobin, an iron-rich protein that gives blood its red color. Each red blood cell contains about 270 million hemoglobin molecules, which reversibly bind oxygen.

Red blood cells are produced in the red bone marrow through a process called erythropoiesis, stimulated by the hormone erythropoietin (EPO), released by the kidneys in response to low oxygen levels. The lifespan of a red blood cell is about 120 days. After that, they are removed from circulation by the spleen and liver, where they are broken down and their components recycled.

Disorders related to red blood cells include anemias (deficiency of functional cells), polycythemia (excess), and shape abnormalities such as sickle cell anemia, caused by a hemoglobin mutation that distorts cells and impairs circulation.

Frequently Asked Questions

What is the main function of red blood cells?

Red blood cells transport oxygen from the lungs to all body tissues and help remove carbon dioxide.

How long does a red blood cell live?

The lifespan of a red blood cell is approximately 120 days, after which it is removed from circulation by the spleen and liver.

What causes anemia?

Anemia can be caused by iron or vitamin deficiencies, blood loss, chronic diseases, or genetic disorders, resulting in low number or poor function of red blood cells.