The structure of a red blood cell and its function.

The primary function of a red blood cell is to carry oxygen from the lungs to tissues around the body, and after to transport carbon dioxide back to the lungs. In order for a red blood cell to carry out its function correctly it requires a unique structure. Red blood cells are approximately 6-8 micrometres in diameter and have a unique biconcave shape. This enables them to squash into the tiny capillaries throughout the body. If they were not able to do this then they would cause obstructions in the circulatory system.

Red blood cells contain a special protein called hemoglobin and it is this that oxygen binds to in order to be transported around the body.

Red blood cells, unlike other cells, contain no nucleus, this combined with their biconcave shape allows for a greater surface area and cytoplasmic volume making them extremely efficient at diffusing oxygen.

The life span of a red blood cell is about 120 days, after which they are retained by the spleen where they are phagocyted by macrophages.

References:

www.helium.com/items/763669-the-functions-of-red-blood-cells

www.funsci.com/fun3_en/blood/blood.hte#3