Red blood cells

Erythrocytes

The red blood cells are also known as erythrocytes. They have a lifespan of 120 days (or four months) and are mainly produced by bone marrows in adults. It has a biconcave shape and is non-nucleated.

The term non-nucleated means that the cell does not contain any nucleus. It has 3 types of haemoglobin (Hb), which make up its globin chains:

• adult HbA (consists of α2β2 chains)
• HbA2 (consists of α2δ2 chains)
• fetal HbF (consists of α2γ2 chains).

Four factors are necessary for red blood cell formation, also known as erythropoiesis. Erythropoiesis requires the presence of the hormone erythropoietin to catalyse its formation, which is produced by the kidney. It also requires iron for Hb production, vitamin B12 and folic acid for DNA and RNA synthesis, as well as intrinsic factors, which help absorb vitamin B12 from the terminal ileum of the small intestine.

The normal haemoglobin value in a person should be between 12-16g/dL. Of course, this range can change according to sex, age, body weight and genetic makeup. It is important for an individual’s diet to consist of iron-rich sources, as this helps in the production of red blood cells. Vitamin B12 and folic acid are also regularly prescribed as supplements for pregnant women.

It will take 3-5 days for the stem cells to form a reticulocyte within the bone marrow. A reticulocyte is an immature form of red blood cells before it enters the blood circulation and matures to become an erythrocyte.