We just learned about the Pathogen.
Another part of how the body fights sickness is an Antigen, also called "Ag".
An antigen is a part of a pathogen disease that the body can use to figure out what kind of disease it is.
It's almost like the disease is wearing a type of sign, mark or color that tells the body what it is.
Once the body knows what kind of disease it is, it can use the right types of white blood cells like T cells or NK cells to go kill the bad disease.
The antigens are made up of things called proteins, peptines or polysaccarides.
Those are just fancy words for chemicals on a disease that look like a sign to our virus fighting immune system.
(from: wikipedia - antigen)
Kid Facts - Blast from the past: Opthalmic Artery
