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Blood types

Learn about the unique properties of blood types and their importance in medical procedures like transfusions. Discover the role of A and B molecules in determining blood types, and how antibodies interact with these molecules. Understand why knowing your blood type is crucial for safe blood transfusions. Created by Patrick van Nieuwenhuizen.

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  • aqualine ultimate style avatar for user Parker Bourassa
    Are these A and B things useful?
    Does having type O, and therefore more antibodies give you a better immune system?
    Just, other than transfusions, why does this matter?
    (14 votes)
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  • winston default style avatar for user David
    How can type O blood be a universal donor?

    If antibodies can bind to molecules in your blood stream, that means that antibodies are in your blood stream (type A and B antibodies for type O blood). So if someone with type O blood donates blood, it's also giving it's antibodies. So how can someone, lets say, type B blood receive type O blood? The B antibodies in the donated O blood type will go and attack all of the original type B red blood cells and would that person then have less blood cells, only the transfused ones? Or will the original antibodies from the type B blood person go and attack the antibodies from the donor? Thanks :D
    (8 votes)
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    • leaf green style avatar for user Chairmanao
      When you donate blood, they have machines that can separate components of whole blood into plasma and red blood cells. Antibodies are generally found in the plasma and in a blood transfusion, only the red blood cells are donated. It's not possible to fully separate plasma and red blood cells, but the amount of plasma and antibodies left in the red blood cell component will be so small, that it will generally not cause a problem.
      However, if an incredibly large amount of blood is needed in an operation, generally it's better to use the same blood type.
      (15 votes)
  • leaf grey style avatar for user patoof
    Is it possible to have antibodies for O?
    (2 votes)
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  • blobby green style avatar for user neolloen111
    Lets say the person has blood type A. It means that this person does not have antigen B on its blood cells. So the immune system has not experienced how antigen B looks like. Then how is it possible that the body makes antibody against an antigen that it has not been exposed to?
    (4 votes)
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  • aqualine ultimate style avatar for user firestar44
    Man, I'm confused. Would someone be able to tell me if the following statements are correct or not?
    Type AB blood can't receive A or B types
    Type A blood can't receive AB or B types
    Type B blood can't receive AB or A types
    Type O blood can receive any blood type

    Thank you in advance.
    (4 votes)
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    • leaf green style avatar for user Joanne
      Your statements are incorrect.
      A person should receive the 'same' type they are, because that is accepted by their immune system. Other blood types are foreign and can cause an immune response, a transfusion reaction, Type A and B have a specific antigen on their blood. Type O has NO or ZERO major antigen on their blood cells.
      In general,
      Type AB can be transfused with Types A, B, AB and O
      Type A can be transfused with Types A and O
      Type B can be transfused with Types B and O
      Type O can only be transfused with Type O.
      There are actually many antigens or molecules on a blood cells that can cause an immune reaction, but these major antigens are the most important ones, along with Rh.
      (4 votes)
  • leafers ultimate style avatar for user Lilli Howard
    A person with A blood wouldn't have B antibodies automatically, would they? They would be only be made after being exposed to AB or B blood. Or are they already there for some other reason?
    (2 votes)
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    • leaf green style avatar for user Joanne
      The maturing immune system of an infant actually does start making IgM antibodies against the "foreign major antigens" by 2 months of age and does not need a blood transfusion to start that process. So an infant with Type A blood would start producing antibodies against B antigens. Prior to 2 months, they would not react. Rh factor is a minor antigen and a person does need exposure to prior to making IgM and then IgG antibodies. With Rh antigen, the first exposure, the Rh negative (Rh-) mother has to be exposed to a Rh+ pregnancy prior to making IgM and then subsequent Rh+ pregnancies will cause IgG to be made, which can cross the placenta and cause hemolysis of the fetal red blood cells. The amount of antibody will increase with each subsequent Rh+ pregnancy. Some things are not as simple as we expect, and transfusion medicine has a lot of interesting details. There are actually hundreds of blood types, and even many Rh antigens. Some Rh antigens are more "antigenic" or more likely to cause an immune reaction then others. https://en.wikipedia.org/wiki/Blood_type
      (6 votes)
  • spunky sam blue style avatar for user Unknown
    what will happen if you give someone with A bloodtype B bloodtype is it lethal.
    (3 votes)
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    • piceratops ultimate style avatar for user Joshua
      If someone with type-A blood receives type-B blood, it is possibly lethal, and can kill the recipient. This is because the person with type-A blood has antibodies that identify type-B blood for attack by the immune system. You don't want your immune system fighting off foreign blood, especially if you have received trauma.
      (4 votes)
  • blobby green style avatar for user Scotty Jones
    Why is it that if type O blood is donated to an individual with any other blood type, that the recipient's natural blood is not marked by the anti-A & anti-B antibodies, on type O, for destruction?
    (3 votes)
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  • aqualine ultimate style avatar for user NoureenAneeze
    At , he said the antibody will attack the same antigen. Then at , he said AB group can receive blood from all types of blood. But then won't the antibody of the donating blood attack the antigen of the receiver? I mean the opposite of what he said at around .
    (3 votes)
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    • leaf green style avatar for user Joanne
      Normally, donated blood cells are separated from most of the plasma and so there are 2 basic points. 1. If the transfusion had little donated plasma, it has little donated antibodies so a reaction by those donated antibodies would be little to nothing. 2. Usually, there would only be a small amount of antibodies anyway in the donated blood, as the body does not make a huge amount unless it is actively fighting the antigen. Therefore the main focus is the recipient. If the recipient receives red blood cells with a foreign antigen, then the recipient's immune system will turn on and potentially start turning out millions of antibodies against the donated antigen that is foreign. Yes. the recipient's immune system can literally do that within minutes, he says the immune system will 'rev up' and that is what he means. It will attack to the point of killing the patient with an agglutination reaction. So, Type AB is the 'universal recipient' because it accepts both A and B as self. Type O in contrast does not have either A or B on its red blood cells, so it does not cause an immune response in any other blood type recipient, so it is the "universal donor." But Type O can only accept Type O because it has NO A or B antigens. Having said that, there are minor antigens that would also be tested for to make sure an agglutination reaction does not occur. (Rh is one example)
      (3 votes)
  • blobby green style avatar for user noursawani
    what is the first line of defance ?
    (2 votes)
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Video transcript

- [Voiceover] Let's say that this is a red blood cell. What makes up the outer layer of this red blood cell? Since it's a cell, it has a cell membrane, and that's made up of lipids. But embedded in those lipids, there's all kinds of proteins and molecules, some of which I'm drawing here, that have all kinds of different functions. There are two of them that are sort of more important than the others, at least for this topic that we're going to talk about, and those are the A molecule and the B molecule. I think you'll be pretty happy with those names, not too hard to remember. I'm actually calling them molecules and not proteins because they're actually not proteins. They are actually something called glycolipids, which I actually didn't realize at first. Glycolipids, glyco meaning a sugar group, lipid meaning a fat group, so it's some kind of mix of a sugar and fat. You can look it up if you're interested. What's interesting, is that not all people have both of these molecules, these glycolipids, on their red blood cells. Some people do have both, but some have only one. For example, some people might have only the A, or, as you can imagine, some people would have only the B, and some people, can you figure out the last possibility? Some people have neither A nor B. Of course, all these people have all kinds of other proteins and molecules embedded in their red blood cells. The reason why we care about this and why I'm talking about these As and these Bs, is that in medicine, we often have to give blood transfusions. Let's say you got in a car accident and you lost a lot of blood. You're rushed to the hospital. If you've lost enough blood, they'll give you a transfusion of blood. Transfusion just means they'll put a needle in your vein and pump blood into your veins. It turns out that you can't just give any blood to anyone, and it has to do with these A and B groups. For example, it turns out, and we'll explain this, but for example, it turns out that if you are the kind of person who has this kind of blood that only has As on your blood cells, then it turns out that you can't get a blood transfusion from someone who has this kind of blood, As and Bs. Let's learn why. If you remember from the immune system, there's something called an antibody. We usually draw it in this shape here. If you remember from the immune system, your body has something called antibodies, and it uses these antibodies to fight things that it doesn't want in the body. For example, if you have a bacterium, I'm drawing one here, you'll have an antibody that will bind to that bacterium. The purpose of that is that now your body knows that is should destroy this bacterium. This antibody is kind of like a tag that marks this guy for destruction. But your body is very careful not to make antibodies against itself, which is obvious, right? If your body made antibodies against itself, then it would start to attack itself. For that reason, someone who has this kind of blood, which means that all of their red blood cells have As and Bs on them, that person would not want to make antibodies against the A and the B molecule, because if they did then their body would attack all of their red blood cells. These people don't have these antibodies. But, let's say if you have this kind of blood, then you might not make an antibody against the A molecule, but you can make it against the B molecule, because the B is not in your body, and so there's no risk that your body is going to attack itself by making an antibody against the B molecule. So these guys don't have the A antibody, but they do have the B antibody. These guys, on the other hand, they can have the A antibody, but they don't want the B antibody because then they would attack themselves. This final guy, can you guess what he has? He can actually have both A and B antibodies. He actually will have both, because that's the way your immune system works. It makes antibodies against pretty much anything that is not you, that is not yourself. A and B molecules are not part of this guy. He has none of them, so he'll make antibodies against them. Let me ask you, what would happen if this guy, someone with just A blood, type A blood, got in a car accident and needed a transfusion? Let's say they're rushed to the hospital and you give them blood from someone with A and B molecules. What would happen is that this guy's antibodies again B would go and bind to the B molecules on the blood that he's just received, and then his body would start to destroy all of these cells that he just received. That's bad because, first of all, it's a waste. You gave this guy blood and now he's just going to destroy it. But second of all, it's going to cause a huge amount of inflammation, because this guy's body is going to suddenly see all these antigens that he thinks are really dangerous, and it's going to cause his whole immune system to rev up, and that will actually be bad for him. Let's go through all the different possible transfusions between these different kinds of people. Let's go through them methodically by drawing a table. On one side of the table we'll have the donors. Bear with me as I draw this table out. We'll have AB donor, A donor, type B donor, and do you know what we call this kind of blood? We can't call it type B or type A because that's these guys, so we actually call this O, type O. Then we also have the same guys as possible recipients, so we have type AB blood recipient, type A blood recipient, type B blood recipient, and type O blood recipient. Let's make this into a table. Here are our donors, blood donors, and here are our blood recipients. What did we say before? We said that someone with type A blood cannot receive blood from someone with type AB blood. So that means that A recipient with AB donor is no good. Well, how about someone with AB blood? Can they receive blood from someone with AB blood? The answer is yes, because the guy with AB blood has no antibodies against A or B, so he won't attack the AB blood that is given to him. Why don't you pause the video for a moment and try to fill in the rest of this table? Hopefully you've paused for a second and tried to fill in the rest of the table. Now we'll fill it in together. Someone with AB blood can receive blood from A, he can receive blood from B, and he can receive blood from O because he has no antibodies to either A or B, so he won't react to any of these guys. Likewise, someone with type A blood can, of course, receive from A, B can receive from B, O can receive from O, but B cannot receive from AB, nor can O. Nor can B receive from A, nor can O. Nor can O receive from B, nor can A receive from B. But O can give to everyone. Something interesting you'll notice here is, as we just said, O can give to anyone because the O blood type has no As or Bs on it, so no one's going to react to it. For that reason, we call O the universal donor. The other interesting thing you'll notice is that AB can receive from everyone. For that reason, we call him the universal recipient. All these things, by the way, AB, A, B, O, these are blood types. So when someone asks you for your blood type, this is what they're referring to. This is why it's really important to know your blood type if you're ever going to require a blood transfusion.