Dr. Megan Johnson McCullough
Special to the Village News
There are four main types of blood: A, B, AB and O. Blood type is determined by antigens found in red blood cells. Each letter refers to a type of antigen. A blood type is also called a blood group. Which type a person has is determined by the genes they get from their parents. Every person's blood is unique because they have their own set of antigens and antibodies.
Most people have 4-6 liters of blood in their body. The cells that float in this liquid are called plasma. In 1901 the Austrian scientist Karl Landsteiner discovered that there are in fact different blood types. Before that, doctors thought that all blood was the same.
Red blood cells deliver oxygen to different tissues in the body and remove carbon dioxide. White blood cells destroy bad invaders and fight infection. Platelets help the blood to clot.
• Blood type is based upon two different antigens: A and B.
• Group A has the A antigen and B antibody.
• Group B has the B antigen and A antibody.
• Group AB has A and B antigens but no A or B antibodies.
• Group O doesn't have A or B antigens but has A and B antibodies.
Rh factor determines if a person's blood is positive or negative. Positive means you have Rh and negative means you do not. Rh is another type of antigen. Therefore, a person can have A positive or A negative, B positive or B negative, AB positive or AB negative, or O positive or O negative blood.
Blood type is important because if two different blood types mix, they can clump and this can be fatal. This can cause a toxic reaction. During a blood transfusion, the donor and recipient must have the same blood types.
Blood types don't always have to be an exact match to be safe. In fact, type O has been referred to as the universal blood type because it used to be thought that it could be donated to anyone. That is not always one hundred percent true. However, type O is considered the safest to donate in times of emergency or when there is limited supply.
Recently there have been claims that people can eat to their blood type to achieve better weight loss results. There is not enough scientific evidence to support this claim yet.
Blood is part of all of us and knowing our type is important in case we ever are in a crisis or can help someone out who is in one. We can safely share and help one another in times of need, but blood is not meant to be freely shared. If you don't know your blood type, ask your doctor and find out. You never know when this information can come in handy.