Warning ~ Please sit down before reading, contents may make you pass out because of confusion.
If someone has a serious injury and starts losing a lot of blood, then a blood transfusion must be performed for him to stay alive. However, even though all blood has the same ingredients, it isn't the same.
The first recorded blood transfusion happened in the 1660s, when a man called Richard Lower attempted to transfuse blood between two dogs. The experiment was successful. However, when he tried to transfuse blood from a lamb into a human, the person died.
In 1818, a man named James Blundell performed the first successful blood transfusion between a man and his wife. However, when more patients died, scientists were vexed as to why the transfusions weren't working.
Finally, in 1901, a man named Karl Landsteiner discovered that red blood cells carry antigens, which are like ID tags to tell your body what blood type you have.
There are two antigen types: antigen A and B. Blood with antigen A fights blood with antigen B. People with both antigen A and B blood have blood type AB, and people with no antigens have O blood type.
Blood with antigen A can be given to people with antigen A blood, same goes for B. O blood can be given to A, B, and AB blood. However, people with AB blood can have both A, B, and O blood. Around 43% of the population has O blood, 40% have A, 12% have B, and 5% have AB blood. Very confusing, right?
Well, it gets even better. In addition to the antigens, blood also contains another tag called the rhesus factor, or Rh factor. If the blood contains this tag, it is said to be Rh positive and if it doesn't have it, the blood is Rh negative.
Rh negative blood cells fight Rh positive cells. However, Rh positive cells don't fight Rh negative blood cells, so people with Rh negative cells need Rh negative blood and people with Rh positive blood can receive both Rh negative or positive blood. Around 85% of the population has Rh positive blood.
Blood type O negative is the universal donor, the most valuable blood type because it can be given to anyone. Blood type AB positive is the universal recipient.
I hope you sat down before reading this article because if you didn't and collapsed on the floor because of confusion, then I am truly sorry. Maybe you didn't read the warning at the top…