|How do you know what blood type you have?|
|Question Date: 2019-03-06|
Everybody has a blood type. The blood type
you have depends on if you have these things
called “antigens”. Antigens are little
proteins found on the membrane of red blood cells.
Think of them as little attachments on the cells
in your blood. The antigens you have are
hereditary, meaning they depend on the antigens
your mom and dad had. There are A antigens and B
-If you have A antigens, you have type A blood.
-If you have B antigens, you have type B blood.
-If you have both A and B antigens, you have type
-If you don’t have either antigen, you are type O
Blood typing is very important because if you
donate your blood to help others, it has to
be the same type. If you give someone blood that
is a different type, their body can reject it and
it can be very dangerous. To determine blood
type, doctors use antibodies. Antibodies are
another little protein that can recognize specific
antigens and attack them. They mix your blood
with different antibodies that attack types A and
B to see how it reacts. For example, if your
blood cells clump together when mixed with the
antibody that attacks type A, you are type B.
If your blood clumps when mixed with the antibody
that attacks type B, then you are type A. I’ll
attach a picture of what it looks like below (that
person has type B blood).
blood type image.
Our blood types can be detected by looking at red
blood cells. Red blood cells are the most common
type of cells in our blood, and they are
responsible for delivering oxygen to all parts of
our bodies. These cells have different things on
their surfaces, and these things are called
antigens. Antigens are small biological things
(smaller than cells) that, if recognized by a body
as a threat, will cause antibodies to be made
(antibodies that stick to the antigens and serve
as tags for the immune system to destroy the
antigen-producing cell). There are two
different major types of antigens called A and
B. Because of these two groups of antigens,
there are four different types of red blood
cells, those with antigen A only,
those with antigen B only, those with
both antigens A and B, and those with
neither antigen A or B. After getting a
small amount of blood from a person, doctors can
use antibodies (made in labs) to detect whether
this person has type A, type B, type AB, or type O
(neither antigen) blood.
There is one other important type of antigen that
the cell surface has, and that is the Rh
antigen group. The most important one out of
this group is the D antigen, and we either
have the Rh D antigen or we don't. People with
this antigen are classified as Rh+, and
people without this antigen are classified as
Rh-. With the ABO system
discussed above, if we see someone's blood type
marked as A-, then we know that this person has
antigen A, but does not have antigen D from the Rh
group of antigens.
Why are these antigens important? Sometimes,
because of injury or illness, people need to get
blood from others. While the antigens on the
surface of red blood cells are not threats to the
human body that makes these red blood cells, the
antigens can be seen as threats by other human
bodies. When the body sees threats, it will
activate immune responses to get rid of these
threats. Therefore, knowing and matching the blood
types of both the blood donor and the blood
receiver can prevent the receiver from starting an
immune response and getting sicker.
Blood type is determined by the combination of
antigens and antibodies (specific types of
proteins related to immune response) in your
Blood types in humans are divided into 4
major groups, with two "types" of each. The major
group is determined by the presence or absence of
the antigens known as A and B. Someone with
A antigens (and B antibodies) has the A blood
type, someone with B antigens (and A
antibodies) has the B blood type, AB has
both A and B antigens but neither A nor B
antibodies, and O type does not have the
antigens but has both antibodies. The final
component of blood type is determined by a
third antigen called Rh. Presence this
antigen is indicated by the additional designation
of "positive" (e.g. type A positive blood),
and absence by "negative".
One way to determine blood type is to see which
antibodies attack it. Antigens
allow the immune
system to identify foreign cells which should
be attacked and destroyed. Notice above that
antigens and antibodies are opposite (e.g. A
antigen with B antibody). This means that the
immune system of a person with type A blood will
see type B blood as foreign and try to destroy it.
In the body, the foreign blood is destroyed
(clumping) of the foreign blood cells when the
antibodies bind to antigens on two blood cells.
The same mechanism can be exploited in
blood typing: a droplet of blood is placed
onto a slide
containing A antibodies and another on a slide
with B antibodies. If the blood clots on the slide
with A antibodies, the blood is type A; vice versa
for type B; if it clots on both, then the blood is
type AB, and on neither means type O. There is an
additional antibody for the Rh antigen which works
the same way.
[For some history about blood types, go
You need to get your blood tested for proteins on
the surface of your blood cells.
You get tested to determine your blood type - ABO
and Rh Factor - positive or negative. I'm A+
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