A negative. What? It’s way more important, what if I need a blood transfusion?

Hey blood brothers and sisters, Julian here for DNews from the youtube space in LA

Even if you don’t know your blood type you’ve probably heard the terms thrown around before.

AB positive. O negative. What do they mean?

It turns out there are actually 33 different systems for categorizing a person’s blood,

but the nomenclature you’re most familiar with is a combination of two of them;

the ABO system and the Rh system.

The reason these two are so much more well known is because they are by and large the

most important factors in blood transfusions. In most cases these alone should be enough

for a doctor to know what kind of blood to pump back into you if you’ve sprung a leak.

It’s why some racing drivers in the ‘70s and ‘80s had their blood type sewn on their race suit

or painted on their car. Nowadays they don’t bother; the tests to determine blood types and compatibility with donor blood

are quick and much more foolproof than relying on embroidery or a sticker.

So what do the letters and plus/minus symbols actually denote?

They’re describing little surface markers on the blood cells called antibody generators, or antigens for short.

Antigens come in a lot of different varieties and your body’s immune system attacks cells

with antigens that don’t match your own. Having the right antigens is like knowing

the password to get into the super secret, boys-only treehouse.

Antigens can be either proteins or sugars. The antigens described by the ABO blood group system

are sugars and they come in 4 different combinations or “types”.

Type O means the blood cells have no A or B antigens, so it might be easier to think of it as type Zero.

People with this blood type can only receive type O because their immune systems

will attack anything with an A or B antigen. But any other blood type can accept type O blood

because the red blood cells will be ignored by the immune system.

Type A means cells have the A antigen so they can’t receive type B blood,

and type B means cells have the B antigen and won’t be compatible with type A blood. I think you see where this is going:

type AB means the red blood cells have both A and B antigens,

and so none of the white blood cells will attack anything with A or B antigens.

People with this blood type can accept any all human blood. Well, so long as the Rh antigens are correct too.

The Rh blood group system is so named because 75 years ago it was discovered the antigens behaved

similarly to those in Rhesus macaques. But they are different,

so don’t go around injecting monkey blood all willy-nilly. Rh antigens are proteins, there are 49 varieties

but one in particular, RhD, is highly immunogenic, meaning immune systems that don’t have it

freak out when they encounter it. So if you have RhD, your blood type has a plus symbol next to it

and you can only donate to other positive blood types, but you can accept positive

and negative blood types. Put the two together and it means O- is the universal donor,

while AB+ will be the universal receiver.

Blood types are passed down through your genes. You can change blood type, but it’s extremely rare.

It either happens from some sort of illness, or if you get a bone marrow transplant

your blood will eventually convert to your donor’s type.

So now you know! Unless you have some rare blood type that needs one of the other 31 blood group systems to describe it,

you now understand what the letters and symbols of your blood type mean.

In some places like Japan it’s believed that blood types also correspond to personality traits,

but really it only affects your immune system. Thinking Type O blood makes a person confident and controlled

is kind of like thinking Jupiter is going to affect your luck today.

Speaking of, here’s Laci talking about why Astrology is silly.

Check the description for a link if you’re on your mobile.

Are there any other things like blood types you take for granted because you just never thought about it?

If you want us to to explain them, go ahead and ask us in the comments,

it’s what we’re here for. I’ll see you next time on DNews.