healthy wealthy and wise

A healthy individual lives in harmony with his/her norrmal body flora, but this balance
may be disturbed by disease. Host defenses are an important factor in determining
whether or not infection will occur. These include anatomic barriers, such as intact skin
and the ciliary muccous sheer in the respiratory trac; physiologic barriers, such as gastric
acid; immun factors, such as specific antibodies, and phagocytic cells, such as polymorphonuclear
neutrophils and macrophages of the reticuloendothelial system.
Presumably, other unknown factors are also involved.