Cell Specialisation: Red Blood Cells

Basic Overview

Red blood cells, also known as erythrocytes, are specialised cells primarily involved in the transportation of oxygen around the body.
The human body produces millions of new red blood cells each second.

Shape and Structure

Red blood cells are biconcave discs - they are doughnut-shaped but without a hole in the middle. This unique shape increases their surface area to volume ratio, allowing for efficient gas exchange.
Unlike most cells, mature red blood cells do not contain a nucleus, mitochondria, or endoplasmic reticulum.

Function in Oxygen Transport

Red blood cells carry oxygen from the lungs to all the cells in the body. They do this using a protein called haemoglobin.
Haemoglobin binds to the oxygen in the lungs and carries it to cells where it’s needed. Once there, it offloads the oxygen and picks up carbon dioxide, a waste product to be exhaled in the lungs.
The absence of organelles, such as a nucleus and mitochondria, provides more space for haemoglobin, enhancing their capacity to transport oxygen.

Lifespan and Production

Each red blood cell has a lifespan of around 120 days. After this, they are broken down in the liver and spleen and recycled to form new cells.
The production of red blood cells is a process called erythropoiesis. It occurs mainly in the bone marrow under the influence of the hormone erythropoietin, which is released by the kidneys in response to low oxygen levels.

Understanding red blood cells and their specialisation is important as it sheds light on how oxygen is transported in the body - a vital process for life.