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  • In a lot of important ways, human beings are pretty similar to one other.

  • But when it comes to blood, there are definitely different types.

  • Eight, to be exact.

  • Our different blood types stem from the fact that we all have immune systems. And while

  • they work equally well, theyre not the same.

  • All of the cells in your body are covered in antigens -- these are special protein markers

  • that function sort of like name tags, sayingThese cells belong to you.”

  • When your immune system detects antigens that aren’t familiar, it triggers the release

  • of antibodies that tag foreign invaders and mark them for termination!

  • Now, there are two main types of antigens that form on your red blood cells. Theyre

  • called agglutinogens; they activate antibodies that smother invaders like a team of rugby

  • players and cause coagulation in the blood.

  • The two kinds of agglutinogens are wisely given the discernible names of A and B.

  • So, your blood cells can have one kind of agglutinogen, or both, or you could have neither.

  • And if you have ANY of these antigens on your blood cells, that means that you don't have

  • any antibody for it. If you did, those antibodies would attack your own cells.

  • On the flip side, you DO have antibodies that would attack the type of antigen that you

  • DON’T have.

  • So, for example, if your red blood cells have A antigens on them, then your blood type A.

  • And your antibodies would attack type B.

  • If you have B antigens on your blood cells, then youre type B, and you have antibodies

  • for type A.

  • If you have BOTH, youre type AB, and you don’t have antibodies for either.

  • And some people have neither kind of antigen. Their genes actually code for an agglutinogen

  • that just doesn’t work, and they have the antibodies for both A and B. These guys are

  • called type O.

  • Now, just to keep things interesting, there’s another set of antigens on your blood cells

  • that works in different ways from the agglutinogens.

  • This is known as the Rhesus, or Rh System, and it’s actually a collection of 45 different

  • antigens. But they're all produced as a single group. So you either have all of them, or

  • you have none of them.

  • If your red blood cells have the Rh antigens on them, we say you're Rh positive. And if

  • you don't, you're Rh negative.

  • So this is how we end up with eight different blood types -- A, B, AB, and O, each with

  • a positive and negative type.

  • Now when it comes to transfusing blood from one person to another, compatibility is kind

  • of important to preventing a serious, possibly life-threatening, reaction.

  • But finding the right match has less to do with what letter you have, than what letter

  • you have the antibodies for which sounds confusing, but let me explain.

  • So, type AB people don’t have antibodies for either A or B, so they can accept A, B,

  • AB or O.

  • But type Os have both A & B antibodies, so they can only accept other Os.

  • And as for the Rh antigens, people with positive blood types can accept either positive or

  • negative blood.

  • But negative-types are safest taking only negative blood. Because while they CAN tolerate

  • positive blood -- they can only do it once. After that, theyll form antibodies against

  • the Rh antigens that they received, which means they can never accept positive blood

  • again.

  • The human body is so weird!

  • Thank you so much for watching this Quick Question, especially to our Subbable subscribers

  • who keep these answers coming!

  • If you have a quick question, let us know on Facebook and Twitter or in the comments

  • below, and don’t forget to go to YouTube.com/scishow and subscribe!

In a lot of important ways, human beings are pretty similar to one other.

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B1 中級 美國腔

什麼是血型? (What are Blood Types?)

  • 297 15
    Zong Shyu 發佈於 2021 年 01 月 14 日
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