Fast facts about red blood cells1

Red blood cells are oxygen delivery packages – they pick up oxygen where its concentration is high (in your lungs) and drop it off throughout your body. They also collect some carbon dioxide from your tissues and take it back to your lungs.

Their technical name is erythrocyte, and there are millions in every drop of your blood. Two million are made in your body every second. Red blood cells are small, even for cells. They are only about 7–8 thousandths of a millimetre across.

Red blood cells are packed with a molecule called haemoglobin. Each haemoglobin molecule contains four ‘globin’ proteins. Each globin is attached to a red pigment called ‘haem’ that contains iron and captures oxygen molecules. This is how your red blood cells collect and transport oxygen.

What’s in a red blood cell?1

You could say there’s not much in a red blood cell. That’s because, as they mature, they lose nearly all of the machinery found in your other cells. They can’t reproduce themselves, or even use oxygen to make energy.

Red blood cells are shaped like a disk and are thick around the edges and thin in the middle (see figure 1). They are very flexible, so can squeeze into tiny blood vessels then spring back into shape when they get to a bigger artery or vein.

How are red blood cells made and broken down?1

Your white blood cells (which make up your immune system and fight infection) and your red blood cells are made in the marrow inside your bones. Stem cells release immature red blood cells, which then develop before being released into your blood. There they mature and are busy transporting oxygen for about 120 days.

When they are worn out, red blood cells are consumed by certain types of white blood cell in the spleen, liver or bone marrow. Some parts of the haemoglobin are recycled for new red blood cells, while other parts might be used to make bile or stored up for later.

How are red blood cells affected by Gaucher disease?2

The bone marrow, spleen and liver are all affected by Gaucher disease. This can lead to not enough red blood cells being created and too many being destroyed, which could mean you don’t have enough. This is called anaemia and can make you very tired.


1. Anatomy and Physiology. OpenStax at Rice University. Published 25 April 2013. ISBN-13: 978-1-947172-04-3. Available at Accessed September 2019

2. Cappellini MD et al. European Oncology & Haematology. 2018;14:50–56.