Nonspecific barriers
A nonspecific barrier is a combination of chemicals and physical protections that include skin, tears, inflammation interferon and fevers. Skin is the first layer of protection. It is very difficult for the microorganisms (germs) to penetrate the dead, woven together cells. But some microorganisms get by the first layer, and the second layer of defense activates. This includes fever and inflammations A fever is fairly simple to understand. The immune system sends out chemicals that increase your body temperature. Interferon are when proteins are produced to prevent viral growth.
Specific Barriers
Specific barriers are the immune system's specific defenses distinguish between "self" and "other". They inactivate or kill any foreign substance or cell that enters the body. A healthy immune system is able to recognize itself (any cell or protein that belongs to the organism). It recognizes a chemical code found on the substance and does not destroy it. Once an "other" is classified, the immune system remembers it after attacking it with chemicals. This is how you can build up an immunity to pathogens.