• Question: why do we have blood types?

    Asked by jamie to Chloe, Irene, Pierre, NULL, Uday on 10 Nov 2015. This question was also asked by 728ntrd26.
    • Photo: Irene Regan

      Irene Regan answered on 10 Nov 2015:

      We have different blood types just like we have different DNA or genetics. But we might not know our DNA but we might know our blood type because it is easier to get a blood type,
      And also we know our blood type when we need to get blood or even give it. It is important to know that we get blood that is similar to ours- we say matches ours.

    • Photo: NULL

      NULL answered on 11 Nov 2015:

      The different blood types A, B, O and AB, are controlled by your genes, so you get them from your parents.

      Why is A different from B, from O and from AB – the differences are in these long sugar molecules that sit on the outside of your blood cells.

      All cells, not just blood cells have lots of different sugars and proteins sticking out of them like tiny antennae. They are slightly different for different types of cells, and they usually let cells recognise each other (since they don’t have eyes…).

      The sugars that give you your blood group actually work in helping blood clot (which is done by blood cells sticking together).

    • Photo: Chloe Huseyin

      Chloe Huseyin answered on 12 Nov 2015:

      Blood types are really important for people that need to have a blood transfusion like during a surgery. The sugars that Ricardo mentioned allow your immune system to know that your blood belongs inside you and that it didn’t come from someone else, if you had blood inside you from someone else your body might have something called an immune response and attack the cells in other blood.

      The blood types are broken into 4 groups which are A, B, AB and O.
      – blood group A has A antigens on the red blood cells with anti-B antibodies in the plasma
      – blood group B has B antigens with anti-A antibodies in the plasma
      – blood group O has no antigens, but both anti-A and anti-B antibodies in the plasma
      – blood group AB has both A and B antigens, but no antibodies

      What this means is that people from blood group A can get a transfusion from groups A and O, group B can get one from B and O, AB can get one from all the groups and is called the universal recipient and blood group O can only get a transfusion from another O, but O blood can be given to any other blood group making it the universal donor. If you mixed that up the person getting the blood transfusion would get sicker because their bodies immune system would attack the cells in the new blood.

      There is another classification then too as red blood cells sometimes have another antigen, a protein known as the RhD antigen. If this is present, your blood group is RhD positive. If it’s absent, your blood group is RhD negative. So all of the four blood types can then be further broken down into smaller groups of either positive or negative for the RhD antigen, giving us A positive, A negative and so on..

      This is why on TV (and in real life too) doctors, if they don’t know what blood group their patient is and the patient needs a blood transfusion in a hurry you might hear them say “Get me some O negative blood for this patient” because O negative blood can be given safely to someone with any blood group.

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