The immune system is nothing if not complex. Anyone who claims to understand it entirely should be shown the door. Still, there is a lot we do know, and we are learning more all the time.
Broadly defined, the immune system's chief function is to protect the body from infection and other pathogens. Its main components include the lymphatic vessels and organs, most notably the thymus gland, spleen, tonsils, adenoids, lymph nodes, and also the liver (though not itself classified as a lymphatic organ).
These act together as a sort of a self-regulating disposal service that constantly rid the body of waste accumulated at the cellular level.
White blood cells, which are produced in the bone marrow, also play a central role. The different types include:
The immune system evolves over time, taking shape in the womb and steadily growing stronger with the rest of the body as it develops. In a sense, you might think of it as a form of defensive memory.
It learns to recognize and destroy specific antigens (external threats), keeping track of such efforts for future reference as it goes along. This is achieved in two ways: cell-mediated immunity and humoral immunity.
Cell-mediated immunity relies heavily on T cells and is primarily concerned with killing foreign pathogens outright. Humoral immunity makes use more of B cells and works by producing antibodies to specific antigens. These antibodies can then either act to disarm antigens themselves or serve as an alarm to call for help in mounting an attack.
What sets the immune system apart from other systems in the body (i.e. respiratory) is that it's not confined to a fixed set of structures and functions. Rather, the immune system is more like a roving band of chemical mercenaries that is forever on the move.
When things are humming along in good working order, all of these individual parts communicate with one another to initiate the proper immune response where required. The degree to which they can mobilize against endless assaults -whether viruses, toxins, or cancer cells- is awe-inspiring!
A key part of the process involves differentiating organisms as either "self" or "non-self". In other words, the forces marshaled by the immune system to fight off potential threats must first be able to detect the difference between a foreign invader and the normal tissues of the body.
When things misfire on this front, the immune system may actually turn on itself and begin to attack what it's supposed to protect. Such is the case in what are referred to as autoimmune disorders, including rheumatoid arthritis, pernicious anemia, lupus, and diabetes.
To operate at its best, the immune system requires adequate nutrients and an environment in which to thrive. Failure to provide either, be it through poor diet, lack of sleep, exposure to pollution, excessive stress, or the overuse of various prescription drugs like antibiotics can quickly throw things out of whack. If left unchecked, the consequences can become extremely serious.
Autoimmune disorders are examples of what can go wrong when the immune system is overactive. But more common, and potentially more deadly, are those that result from it being compromised: a condition characterized as immunosuppression. AIDS (Acquired Immune Deficiency Syndrome) is the most notable of these types of conditions.
Not every immune breakdown, however, is so dramatic. Things as minor as the occasional sore on the tongue or winter cold are the result of your immune system not being up to par. Fatigue, allergies, candida, and frequent yeast infections are additional signs to watch out for.
Aging itself may well be a product of an impaired immune system in one form or another! Thus, please keep in mind that whether you're talking about preventing cancer, beating a slight cough, or just knocking a few years off the clock, your immune system is where the action is.
So how do you make it stronger? The short answer is to start building up the body in general. To learn how, I encourage you to follow what I call "The Six Steps to Optimal Health".
The Six Steps are these: