Objective 21: Blood typing

• Types A, B, AB, and O
• Based on the presence of absence of two agglutinogens (A and B) on the surface of red blood cells
• Blood may contain Anti-A or Anti-B antibodies (agglutinins) that act against transfused RBC's with ABO antigens not normally present
• Anti-A or Anti-B form in the blood at about 2 months of age

Ok, dont ask me why....but this confuses me, STILL.  I get it in writing...the facts above all make perfect sense.  I have a clear understanding of what agglutinogens are and how the antibodies present in the blood will attack a foreign substance (ie: a different blood type).  However, when I see an actual blood sample, for some reason I can not figure out which one I'm looking at.  Maybe a little more time studying the chart below will help me!

Anatomy and Physiology textbook*