Fun Fact - Deoxygenated Blood Colour Is Not Blue

"Deoxygenated blood colour is blue." Once again, we have been taught another lie from our childhood. We'll debunk this myth today. This is the second article about fun facts. You can read more about fun facts by going to:

Fun Facts - Read To Get Surprised.

What's oxygenated and deoxygenated blood?

Colour of oxygenated blood is blue and colour of oxygenated is red. Before debunking this myth, let's debunk another common myth. Blood flows through arteries, veins and capillaries. Everyone thinks that oxygenated blood flows through arteries (except pulmonary artery). That's simply wrong.

• There's no such thing as oxygenated blood.

All of you know about the blood that:


It circulates to different areas of our body to provide the cells with nutrients, oxygen (O2). Cells utilise them to produce ATP for our body and also generates carbon dioxide (CO2) and other metabolic wastes. Blood also carries those excretory products and CO2 out of the cells and they are later eliminated in the form of urine or via other excretory methods.

Blood flowing through any artery is never fully saturated with oxygen (O2). So, if blood isn't 100% saturated with oxygen, you can't call it oxygenated blood.

• Blood is always more or less deoxygenated.

Confusions about colour of blood

Blood contains Haemoglobin which is made up of four heme groups. Iron (Fe) molecules can bind to this heme proteins. On the other hand, Iron molecules can bind with oxygen.

• The red colour of the blood is due to the interaction between the iron and oxygen molecules.

Venous blood carries less oxygen that arterial blood. That's why:

• Arterial blood is light red in colour. And Venous blood in dark red in colour.

But veins appears as greenish blue in colour. So, what's the matter? You're probably pretty much confused by now.

The reason behind the greenish blue appearance

Veins reside pretty close to the surface of the skin. Subcutaneous (beneath the skin) fat layer can only deflect blue or violet light. Skin pigment prevents the deflection of other colours.

So there you have your answer:

• Less saturated, deoxygenated blood colour is dark red.