• Question: Whats the real color of the blood

    Asked by Aaron?? to Kevin, Jonathan, Kellie, Melissa, Stephanie on 28 Apr 2016. This question was also asked by HarryPotter101.
    • Photo: Kevin Baker

      Kevin Baker answered on 28 Apr 2016:

      Blood is actually red because of red blood cells. When people say blood is blue, this is incorrect. The blue they are seeing are the blood vessels.

    • Photo: Stephanie Moon

      Stephanie Moon answered on 28 Apr 2016:

      I love this question. Like Kevin said, blood is red because of special cells called erythrocytes (red blood cells). They are really cool because they are totally full of hemoglobin, the protein that carries oxygen in your blood. Hemoglobin has a crazy looking molecule in it called heme that contains an iron atom, and this is what actually binds to oxygen to carry it around. When the oxygen is attached to iron in hemoglobin, it turns the protein bright red (like you see in blood from an artery that’s been freshly loaded with oxygen). When oxygen is not attached (like you would find in your veins when the blood is going back to the heart to get re-oxygenated) it’s a dark reddish-purple color. So it does change color depending on the oxygen. When I was in college, we got to do a cool laboratory experiment where we actually measured this difference in color when human blood is oxygenated and de-oxygenated. It was awesome to be able to see a change in color that was directly related to a chemical interaction.

    • Photo: Jonathan Jackson

      Jonathan Jackson answered on 28 Apr 2016:

      Um, I know this question was for Aaron, but I learned something new, too! Thanks, Kevin and Stephanie!

    • Photo: Kellie Jaremko

      Kellie Jaremko answered on 28 Apr 2016:

      Hi Aaron,

      Good question and both Stephanie and Kevin did a great job explaining. It is interesting that the color of an animal’s blood depends on the protein they use to carry oxygen and other chemicals throughout their body. If an octopus was bleeding it would be blue and here’s a great pic to explain http://www.compoundchem.com/2014/10/28/coloursofblood/ As humans our blood is always a shade of red and here’s a youtube video to explain: https://www.youtube.com/watch?v=18–LFIs-FM

    • Photo: Melissa Wilson Sayres

      Melissa Wilson Sayres answered on 30 Apr 2016:

      We could also think about the different components of blood. In some studies of gene expression (which genes are turned on or off) we analyze blood samples, but blood is composed of many different types of cells (e.g., red blood cells, white blood cells, platelets) and plasma with all sorts of interesting things in it: https://en.wikipedia.org/wiki/Blood.

      These are actually all different colors, and each have a unique signature of gene expression.