The immune system is the body's defense system.
Protecting us from foreign particles that enter
our body. The Immune System is the name of a collection of molecules,
Cells and organs whose
complex interactions form an efficient system that is usually able to protect an individual
both outside invaders and its own altered internal cells.
This combination of components is the product of millions ofyears of evolution, which has selected
those Organisms that are best able to prevent their destruction by
Micro-organisms or tumors.
Perhaps an unknown fact concerning the Immune System is that it works best when
it doesn't have
to work at all. Thus if the infectious organism is unable to enter
an individual's body, for whatever
reason, no immune response need be mounted and the person is healthy.
Two body features which are not normally associated with the Immune System also serve
important functions: the Skin, and the Mucosa. While it seems elementary, the importance
of Skin in resisting infection can not be overemphasized. It is the location at
Micro-organisms are stopped.
To appreciate its importance, it is worthwhile to consider the relative frequency of lesions forming
on healthy intact skin, as compared to infections at locations where the skin has
The less effective, but close cousin of the skin is the Mucosa: the tissue which covers our
alimentary and genital & urinary tracts. As the higher frequency of mucosal infections indicate,
it is not quite as effective at resisting the myriad of challengers to which it is subjected.
Since this tissue is easier to penetrate than normal skin, it possesses a number of means to
dissuade the frequent microscopic interlopers. Tears and aaliva, as well as other
act to wash away many potential invaders, and many also contain
chemical elements which are
effective in killing microbes.
There are several cells that serve the Immune
system: B Cells and T Cells.
T-Cells are responsible for destroying infected or
cancerous cells, and for coordinating all
acquired immune responses. Thus, T-Cell immunity is generally called
B-Cells are the generators of humoral immunity, so called
because it consists of soluble
proteins found in the "Humors" (Blood).