Welcome to brain Stop from house stuff works dot com where smart Happens. Hi, I'm Marshall Brain with today's question. Are all blood types needed for donation? So let's start at the beginning. A blood group or a blood type is based on the presence or absence of two different proteins called A and B on the surface of red blood cells. Because there are two proteins involved, there are four possible combinations or blood types known as A bio groups.
There's type A blood where only the A protein is present, There's type B blood where only the B protein is present. There's type A B blood where both proteins are present, and then there's type O blood where neither protein is present. And this is about the population. In addition to the A and B proteins, there's another protein involved called the rh factor RH for reesus monkeys where it was first identified and the RH factor is either present plus or
absent minus. Therefore, blood types are described as the type and the RH factor, such as O positive or A positive or A B negative. So how do they figure out what your blood type is? Blood types are determined by placing three drops of blood on a glass microscope slide to one drop of blood, a drop of antibodic solution to protein A known as anti A, is added.
To the second drop, a drop of antibody solution of protein B is added, and to the third drop a drop of antibody solution to r H factor is added. The blood drops and the antibody drops are mixed and examined for clumps of red blood cells, and the blood type is determined by which blood cells form clumps. Clumps mean that the particular protein A, B, and r H is present. For example, clumps in anti A and anti r H but not in anti B would indicate a
person with type A plus blood. Now, these clumps are important because that can happen in real life as well. When blood is given from one person to another, known as a transfusion, the blood types have to match. If they're not matched properly, the recipient will form these clumps in response to the donor's blood. The clots will lead to heart attacks, embolisms, and strokes. It's called a transfusion reaction. And when thinking about these reactions, two types are special.
There's type OH minus blood. It's called the universal donor because it can be given to anybody. It has no proteins that can cause the clumps. And then there's type A B positive, which is known as the universal receiver because the recipient has all the proteins and so none of these clumps are going to form no matter what kind of blood is pumped in. Finally, the RH factor
is important for pregnant women. If an RH positive man and an RH negative woman have a child, the child can be either RH positive or RH negative, depending on the GENA type of the father. If the baby is r H positive, this can cause problems because it's different from the mother's RH type. While in the womb, some blood cells from the baby will cross the placenta into the mother's bloodstream. The mother will make antibodies to the
RH positive cells. If the woman becomes pregnant again, and if the baby is r H positive, the mother's anti RH antibodies will cross into the baby's blood and destroy its red blood cells, which can kill the baby. If diagnosed early, it's possible to save the baby under these circumstances by replacing the baby's blood with transfusion that are
free of the r H antibodies. Also, if this situation is known, it's possible to treat an RH negative woman with an anti rh antibody drug immediately after childbirth to inactivate the baby's r H plus cells and prevent the mother from forming these anti rh antibodies in the first place. This is called desensitizing her to the RH factor. Be sure to check out our new video podcast, Stuff from the Future. Join how Stuff Work staff as we explore
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