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Facts About Blood Types


Blood groups (A, B, AB, and O) are inherited. The presence or absence of an Rh factor on the red blood cells is what makes your blood type positive or negative. Blood groups (A, B and O) and Rh types are descriptions of certain antigens found on red cells. People with type A blood have A antigens on their red blood cells and lack B antigens; people with type B blood have B antigens and lack A antigens; people with type AB blood have both antigens, and people with type O blood lack both A and B antigens.

In addition, blood is typed as either Rh-positive or Rh-negative, referring to the presence or absence of the Rh antigen, which is named for the fact that it was first discovered in the Rhesus monkey. Most people (about 85 percent) are Rh-positive, and that figure is even higher for African-Americans and Asians.
Out of 100 people, about:
38 will be O positive
7 will be O negative
34 will be A positive
6 will be A negative
8 will be B positive
2 will be B negative
4 will be AB positive
1 will be AB negative

Who Can Receive Whose Red Blood Cells:

O negative can use O negative only

O positive can use O positive or O negative

A negative can use A negative or O negative

A positive can use A positive, A negative, O positive or O negative

B negative can use B negative or O negative

B positive can use B positive, B negative, O positive or O negative

AB negative can use AB negative, A negative, B negative or O negative

AB positive can use All Blood Types

Notice that all blood types can receive O negative red blood cells. This is why O negative is used in emergencies when there is no time to determine the blood type of the patient. This is also why donors who are O negative are always in high demand.

Blood is composed of cells suspended in a liquid. These cells -- red cells, white cells and platelets -- account for 50% of the volume of blood. The remaining liquid portion is plasma.

Red cells are as important to life as breathing in and out. They transport oxygen throughout the body cells. The oxygen provides the fuel, or energy, for all the work your body does. Red cells need foods rich in iron, such as meat, liver, eggs, green leafy vegetables and whole-grain bread to make them healthy. Red cells are produced in the bone marrow at a normal rate of about 17 million cells per second.

White cells, also known as leukocytes, are the protective cells in the blood stream. They attack bacteria by squeezing through capillary walls to reach the area of infection where they destroy bacteria. White blood cells are also made in the bone marrow and are produced at twice the rate of red blood cells.

Platelets are colorless cells or fragments produced in the bone marrow. They control bleeding by helping to form a blood clot. Platelets also assure that blood vessels stay "leakproof" in daily life by acting like an internal band-aid.
Plasma contains minerals, proteins, sugars and hormones and is the liquid through which all blood cells "swim".


Over 100 years ago, it was discovered that different people have different types of blood. The major types are 'O', 'A', 'B' and 'AB'.

For a blood donation to be helpful to a patient, there has to be a good match between the blood type of the donor and that of the patient receiving the blood. While receiving blood from someone of exactly the same type is fine, some types can happily mix with certain others, while others do not mix well. The common Type O can be given safely to patients with A, B or AB blood. But Type O patients can only receive blood from other Type O people.

Each major blood group is divided into Rh negative or positive types. On average, 45% of the population is Type O, 40% Type A, 10% Type B and 5% Type AB.



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Blood group basics .O A B postive negative.

Blood group basics


OK, folks, this page requires your full attention as it's all about the complicated differences between everybody's blood types. I've tried to make this as simple as possible.

Here we go.

We all have these little marker things called antigens on the surface of our red blood cells.

These are so tiny they can't even be seen under a microscope.

Everyone's got different ones - blame your parents and grandparents for all that.

In fact, only identical twins will ever possess all the same antigens.

All that's very well and good, but when it comes to blood transfusions, there are two very important systems of antigens which need to be matched to avoid any nasty complications.




The ABO System

If you have blood group A then you've got A antigens covering your red cells.

Blood group B means you have B antigens, while group O has neither, and group AB has some of both.

The ABO system also contains lots of little antibodies in the plasma, antibodies being the body's natural defence against foreign antigens.

So blood group A has anti-B in their plasma, blood group B has anti-A (you probably get the picture at this stage).

To complicate matters though, group AB has none and group O has both of the antibodies.

Which means giving someone blood from the wrong ABO group could be fatal.

The anti-A antibodies in group B attack group A cells and vice versa.

Which is why group A blood must never be given to a group B person.

Group O negative is a different story.

The Rh system

Still with me?

Well, it gets more complicated here on in, because there's another antigen to be considered - the Rh antigen.

Some of us have it, some of us don't.

If it is present, the blood is RhD positive, if not it's RhD negative.

So, for example, some people in group A will have it, and will therefore be classed as A+ (or A positive).

While the ones that don't, are A- (or, wait for it...A negative).

And so it goes for groups B, AB and O.

This effectively doubles the number of different blood types to be matched, because you shouldn't mix blood type A+ with blood type A-.

84% of the population is Rh positive.

(And yes, that means the other 16% of the population is running around with Rh negative blood.)

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