In Japan, asking somebody’s blood type is right up there with asking “what’s your sign?” Blood types are assigned personalities—A is the Farmer: serious, composed, and trustworthy. B is the Hunter: cheerful, enthusiastic, unpredictable. AB is the Humanist: distant, careful, considerate, sensitive. O is the Warrior: expressive, clumsy, natural leaders, generous. Here’s what your blood type actually means.
The main components of blood are red blood cells, white blood cells, plasma, and platelets.
Red blood cells are simple little cells that have been stripped down to the bare essentials. Their only job is to carry oxygen around your body. You can think of them like mailmen, where oxygen is the mail they’re delivering. If you’ve heard of hemoglobin, it’s a protein that acts as a giant mailbag looped all around the mailman to hold on to the oxygen as the red blood cells travel.
White blood cells are armed with proteins called antibodies, and if you’re healthy they are only present in small amounts—they’re there to fight infection, so more are made when they’re needed. When strangers break into your body, the antibodies recognise certain features of these strangers and set out to kill them (like unwanted bacterial cells).
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Plasma is a yellowish liquid, made 90 per cent of water. It acts as the river through your bloodstream that your other blood cells travel in. Platelets are little guys that help you stop bleeding when you get cut. They buddy up and clog your open wounds, and recruit some other protein friends to help.
So what does my blood type mean?
The most important blood grouping system for human blood transfusions is the ABO system. We have four blood types: A, B, O, and AB. The letters refer to a kind of protein called an antigen, located on the surface of red blood cells. For example, the surface of red blood cells in Type A blood has antigens known as A-antigens. Blood also contains antibodies, which are the part of our immune system that protects us from infection. Antibodies attack and kill cells which have antigens they don’t like.
Our immune system is primed to notice strange, potentially dangerous new things, and destroy them. Unfortunately, depending on your blood type, you may have antibodies that don’t like antigens found in other people’s blood. For example, Antibody A kills cells with Antigen A. This means that not all blood types are compatible, and that if you receive blood from the wrong person your immune system will destroy the red blood cells that were given in the transfusion—this can be fatal! So long as the blood types of the donor and patient are known, it is easy to keep things safe. This is how it works:
A-type blood has Antigen A and Antibody B. B-type blood has Antigen B and Antibody A. O-types are grumpy haters who have none of their own Antigens and can’t tolerate anyone else’s, because they have both antibodies. Holistic AB folks have both antigens and don’t hate nobody because they have no antibodies.
If Alison A-type is in need of blood, she can’t get it from anybody with Antigen B because her B antibodies will get mad. She can only receive blood from antigen free Olivia O-type, or a fellow A-type. If Alison was giving her blood away, however, she can only give it to the all-accepting AB or a fellow A, because everyone else has B Antibodies.
Because Olivia O-type doesn’t have antigen A or B, she can’t upset anybody, and can give her blood to anybody. But because she has both antibodies, she can only get blood from another O. This is why O is considered the “universal donor type”. AB has both antigens, so while no one who isn’t also AB wants his blood, he’ll let anybody in. Thus AB is the “universal receiver type”.
On top of that, our blood decided to throw in one last prejudice. Positive and negative. The Rh blood group system is based on whether or not you have the “Rh factor” protein antigen. You’re either Rh Positive, or Rh Negative. Rh+ is fine with Rh+ or Rh- donors, while Rh- won’t accept donations from Rh+.
What happens if blood isn’t compatible?
When somebody needs a blood transfusion, it’s crucial to make sure the ABO blood type is determined and the donor and recipient are compatible. If an error occurred—and unfortunately sometimes this does happen—and incompatible blood was given in a transfusion, this can cause what is called an Acute Hemolytic Transfusion Reaction.
Upon transfusion of even a few milliliters of blood, it can occur anywhere between one and 24 hours. The introduction of unwanted antigens causes the recipients antibodies to get very hostile and attack and destroy the new red blood cells. Accelerated loss of red blood cells can cause problems such as anemia, jaundice, and Disseminated Intravascular Coagulation (DIC).
In cases of anemia, your lack of red blood cells slows oxygen delivery throughout your body. Jaundice is caused by the destroyed red blood cells spilling their cellular components everywhere, filling your extracellular fluid with unwanted mess like bilirubin—a waste product that contributes to the yellow in your urine and brown in your feces. The increased levels of bilirubin floating around causes your skin to turn yellow!
DIC is the coagulation of blood inside your body. Along with bilirubin, some of the mess spilled from the dying red blood cells is a protein called Tissue Factor, which isn’t supposed to be allowed to float around your blood alone. The wrongly freed Tissue Factor irritates features in your own blood, causing it to clot throughout your vascular system. This vasculature roadblock can prevent your mailmen red blood cells from delivering oxygen to entire organs, resulting in complete organ failure.
Yikes! Why would I let blood into my body if that might happen?
Your body can’t survive without enough functional blood. As well as oxygen, it works to transport large amounts of important products around your body and to perform vital functions. If you’re involved in an accident, an immediate blood transfusion may be performed.
There are also some unfortunate conditions that require patients to get regular transfusions, because their blood simply doesn’t work properly. Sometimes illnesses stop your body producing enough healthy blood itself, for example some bone marrow diseases that limit red blood cell production, or thrombocytopenia, which decreases your platelet levels. Severe infections, cancers, and organ diseases can also stunt your blood production, so blood transfusions can give your body the top up it needs to keep working. Inherited conditions like hemophilia and Von Willebrand disease stunt blood clotting, which can result in severe blood loss from just a small cut.
Every donation can save up to three peoples’ lives. The 10-second needle prick you dread may give a child in need the 80 years they deserve.