Red blood cells flowing

Red blood cells, or erythrocytes, are blood cells crucial for transporting oxygen from the lungs to the body's tissues.

About this subject

Red blood cells, also known as erythrocytes, are the most abundant cells in human blood. A healthy adult typically has between 4.5 and 5.5 million of these cells per microliter of blood. Their biconcave shape increases the surface area for gas exchange and allows them to deform to pass through narrow capillaries. Unlike other cells, mature erythrocytes lack a nucleus and organelles, maximizing internal space for hemoglobin storage.

Hemoglobin is the protein responsible for binding oxygen in the lungs and releasing it in tissues. Each red blood cell contains about 270 million hemoglobin molecules. These cells are produced in the red bone marrow, primarily in bones such as the sternum and ribs. The production process is stimulated by erythropoietin, a hormone released by the kidneys when oxygen levels are low.

The lifespan of a red blood cell is approximately 120 days. After that, aged cells are removed by the spleen and liver. Hemoglobin breakdown produces bilirubin, which is excreted in bile. Abnormalities in red blood cell count or function can lead to conditions such as anemia (low count) or polycythemia (high count), both with significant clinical implications.

Frequently Asked Questions

What is the main function of red blood cells?

The main function of red blood cells is to transport oxygen from the lungs to the body's tissues and to assist in removing carbon dioxide.

How many red blood cells are in the human body?

A healthy adult has about 20 to 30 trillion red blood cells circulating, which corresponds to approximately 4.5 to 5.5 million per microliter of blood.

What causes anemia?

Anemia can be caused by iron deficiency, blood loss, low production of red blood cells (due to bone marrow disease), or excessive destruction of these cells.