Structure of the Immune System
Where is it?
The first is your skin. Like the wall of a fortress, it keeps most intruders out. But the openings, such as the mouth, nose or ear, have their own tricky traps. The nose has nose hairs and the ears have ear wax to trap the germs. The saliva in the mouth melts them, as it is like acid. If they do get past those, the acid in the stomach melts them also. But germs are sneaky; they sometimes get into the bloodstream. Then, leukocytes patrolling your blood call up T-cells to eat them, or use antibodies.
Where Are They?
Your mouth, nose and ears are on your head, right in your T-zone. Your stomach is located almost right below your ribcage. It is about the size of your fist. Your white blood cells are in your bloodstream, which runs all over your body. The germs, of course, are everywhere. Literally!