Overview
This lecture explains the physiology behind blood types, focusing on antigens, antibodies, and compatibility—important for understanding blood transfusions and immune responses.
Immune System and Antigens
- The immune system protects the body from foreign invaders using white blood cells.
- An antigen is any substance the body recognizes as foreign.
- White blood cells detect antigens and produce antibodies to attack and remove them.
Blood Types and Antigens
- Red blood cells have antigens on their surfaces, mainly the ABO and Rh antigens.
- Blood types include A, B, AB, and O, based on the presence or absence of A and B antigens.
- Type A: A antigens on red blood cells.
- Type B: B antigens on red blood cells.
- Type AB: Both A and B antigens present.
- Type O: No A or B antigens present.
Antibodies and Blood Type Compatibility
- Type A blood has anti-B antibodies.
- Type B blood has anti-A antibodies.
- Type AB blood has no anti-A or anti-B antibodies.
- Type O blood has both anti-A and anti-B antibodies.
- Receiving incompatible blood causes agglutination (clumping), blocking vessels and risking organ failure.
Blood Transfusion Rules
- Type A: Can receive from A and O.
- Type B: Can receive from B and O.
- Type AB: Can receive from A, B, AB, and O ("universal recipient" with caveat).
- Type O: Can only receive from O but can donate to all types ("universal donor" with caveat).
Rh Factor
- Rh positive: Has Rh antigen; no anti-Rh antibodies produced.
- Rh negative: Lacks Rh antigen; produces anti-Rh antibodies if exposed to Rh+ blood.
- True universal recipient: AB positive (AB+).
- True universal donor: O negative (O-).
Key Terms & Definitions
- Antigen — a substance the immune system recognizes as foreign.
- Antibody — a protein produced by white blood cells to target antigens.
- Agglutination — clumping of red blood cells due to antibody binding.
- Rh factor — an antigen that determines if blood is Rh positive or negative.
- Universal recipient — a person with AB+ blood who can receive any blood type.
- Universal donor — a person with O- blood who can donate to any blood type.
Action Items / Next Steps
- Review your own blood type and its compatibility.
- Understand transfusion rules for ABO and Rh systems.