For most people, knowing their blood
type is about as relevant to their day to day lives as knowing the
capital of Chad (N'Djamena). Yet,
with blood it is a difference between life and death so we had to ask,
what is up with blood types, and why do they matter?
Although you can’t judge a book by
its cover, you can judge a red blood cell by its surface.
The ABO blood typing system works by identifying which (if any)
antigens (microscopic protein markers) you have on your red blood cells.
The A antigens make for type A blood.
B antigens make for type B.
Both A and B make for AB blood, and neither A nor B makes for
type O (which you can think of as a zero since it means that the red
blood cell has neither of the antigens). So everyone in the world falls into one of the four
categories: A, B, AB, or O.
Then to the letter you have to add a
plus or minus sign to indicate the Rhesus or Rh factor, which was named
after the monkeys being studied when they found yet another antigen
(marker) which only some people possess (actually over 80%).
This time there is only one antigen so if you have it you are
positive (+) and if you don’t you are negative (-).
|
Blood
Type
|
Percentage
in the U.S. Population
|
|
O
+
|
38
|
|
A +
|
34
|
|
B +
|
9
|
|
O -
|
7
|
|
A -
|
6
|
|
AB +
|
3
|
|
B -
|
2
|
|
AB -
|
1
|
Simple enough right?
Blood type is just a letter and a sign, but why do we need to
know that? The answer is
because if you receive the wrong type of blood it could be fatal. The only blood type that can be given to everyone (the
universal donor) is O negative, and as you can see above, it is
relatively rare. The rest
of the blood types vary in how fussy they are about mixing with other
blood types.
Of course there is more to your blood
than just red blood cells (platelets and white blood cells primarily),
but at least now you know why blood type does matter.
Did
you know you could make a career out of studying blood?
Hematologists are doctors who study diseases of the blood - you might
want to check it out.
