lnfectious diseases are caused by __________, bacteria, fungi, "protists", and other pathogens.

The most wide spread nonspecific defense is the ______, a physical barrier that keeps most pathogens out of the body. 

An _________ is any foreign substance that can stimulate an immune response.

Allergic reactions in the respiratory system can createa dangerous condition called ____________.

Type | diabetes is an autoimmune disease in which the immune system attacks insulin-producing cells in the ___________.