Natural immunity
The natural immunity is the set of processes that prevent so naturally and spontaneously to healthy individuals from infection by pathogens.
There are two types of natural immunity:
This is the immunity that the body acquires when it synthesizes antibodies after the introduction of the antigen. The natural immunity active is then acquires overcome an infectious disease, because the body is loaded with antibodies synthesized and, especially, with lymphocytes memory, so that for a time (sometimes life) the prevents reinfection. For example, immunization against chicken pox.
The passive natural immunity is acquired receiving antibodies specific made by another organism. It is produced by the transfer of antibodies from the mother to the fetus, through the placenta, and to the nursing child through breast milk ("colostrum"). In this way, the child receives antibodies until his immune mechanisms are fully developed.