Red blood cells flowing

Red blood cells, also known as erythrocytes, are blood cells responsible for carrying oxygen from the lungs to the body's tissues.

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Red blood cells, or erythrocytes, are the most abundant cells in human blood, with about 5 million per microliter. Their primary function is to transport oxygen from the lungs to all body tissues and remove carbon dioxide. This task is carried out by hemoglobin, an iron-rich protein that binds to oxygen and gives blood its characteristic red color.

Produced in the red bone marrow, erythrocytes have a lifespan of approximately 120 days. During that time, they travel about 300 kilometers through blood vessels. Their biconcave disc shape increases surface area for gas exchange and allows them to deform to pass through the narrowest capillaries.

Red blood cells lack a nucleus and organelles, providing more space for hemoglobin storage. This absence also prevents cell division, so they are constantly replaced by the bone marrow. On average, the human body produces 2 million new erythrocytes per second.

Changes in red blood cell count or shape can indicate diseases such as anemia (low count), polycythemia (high count), or hereditary anemias like sickle cell disease, where the cells become sickle-shaped and impair circulation.

Frequently Asked Questions

What is the main function of red blood cells?

The main function is to transport oxygen from the lungs to the body's tissues and help remove carbon dioxide, thanks to hemoglobin.

Why do red blood cells lack a nucleus?

The absence of a nucleus and organelles allows more space to store hemoglobin, maximizing oxygen-carrying capacity.

How long does a red blood cell live?

The average lifespan of a red blood cell is about 120 days, after which it is removed by the spleen and replaced by new cells from the bone marrow.