• Question: why are my veins blue

    Asked by fast1say on 10 Mar 2024. This question was also asked by aced499pan.
    • Photo: Simone Girdham

      Simone Girdham answered on 10 Mar 2024:

      It is the fluid inside your veins that makes them look blue.

      Blood contains red blood cells (ie when you cut yourself the red stuff) which are made up of a thing called haemoglobin.
      Haemoglobin is a very special compound. It loves oxygen and carbon dioxide.

      As your blood goes through your lungs, you breathe in oxygen and this attaches to the haemoglobin. This turns the blood bright red.

      Then, your heart pumps the haemoglobin around your body, via arteries, giving oxygen to your cells which helps you stay alive and grow.

      Your body’s cells give back carbon dioxide to the haemoglobin, making your blood look a dark red.

      The blood returns through veins to your lungs, where you breathe out the carbon dioxide.

      Veins have thinner walls (think of a straw versus a water pipe) and some lie close to your skin, so you can see the blood through the wall.

      Natural light now comes into play – think of a rainbow – light consists of different colours which are able to go different distances. Red light is absorbed by your blood, but blue light is unable to penetrate your skin, so the blood in your veins looks blue.

    • Photo: Amber Villegas - Williamson

      Amber Villegas - Williamson answered on 12 Apr 2024:

      Simone has provided an excellent response to this question.

    • Photo: Kirsty Lindsay

      Kirsty Lindsay answered on 15 Apr 2024:

      Interestingly octopuses have blue blood, so their veins look a red-brown, because for them, blue light is absorbed and red light is reflected