What Is a Blood Type?
A blood type is a classification of blood based on the presence or absence of specific inherited substances, called antigens, on the surface of red blood cells. These antigens can trigger an immune response if they are foreign to the body. The two most important blood group systems for classifying blood are the ABO system and the Rh system.
Section 2: The ABO and Rh Systems
The ABO system classifies blood into four main types: Type A (has A antigens), Type B (has B antigens), Type AB (has both A and B antigens), and Type O (has neither A nor B antigens). The Rh system classifies blood as either Rh-positive (Rh+) if the Rh antigen is present, or Rh-negative (Rh-) if it is absent. Combining these two systems gives the eight common blood types, such as A+, B-, or O+.
Section 3: A Practical Example
Consider a person with Type A+ blood. This means their red blood cells have A antigens and the Rh antigen on their surface. Their plasma contains antibodies against B antigens. If this person were to receive a transfusion of Type B blood, their anti-B antibodies would attack the transfused red blood cells, causing a potentially life-threatening reaction.
Section 4: Why Blood Types Are Important
Knowing a person's blood type is critical for safe blood transfusions. Matching the donor's and recipient's blood types prevents the recipient's immune system from attacking the transfused blood. Blood types are also important in genetics, as they are inherited from parents and can be used in paternity testing. Additionally, certain blood types are associated with different risks for medical conditions.