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A Short Overview of the Human Immune System

Updated on May 11, 2011

Your immune system is an amazing and complex biomechanism of responses to attacks from foreign intruders in your body. It is what keeps you healthy, strong, what helps you fight illness and infections. Without the immune system you wouldn't last a day.

The immune system is composed of many subsystems that work together constantly. The blood and lymph systems in your body are responsible for transporting the agents of the immune system. Part of the immune system are the bone marrow, the spleen, lymph nodes and lymphocytes. Also:

  • Antigens (involved in immune memory and trigger immune response to specific pathogens)
  • Histamine (chemical that builds around infected area to attracts immune response molecules. It is responsible for the inflammatory reaction of the immune system)
  • Cytokines
  • NK cells
  • Macrophages
  • T cells
  • Probiotic bacteria (responsible for keeping healthy environment in your GI tract)
  • Leukocytes (white blood cells or WBCs) and Thrombocytes (platelets)
  • Lymphocytes (consisting of B cells and T cells) and Monocytes

The immune system complex is known to consist of two major layers:

  • Innate immunity - non specific.
  • Adaptive immunity - antigen specific.

The innate immunity system is genetically based. Each individual is born with certain innate immunity and will pass a part of it to their children. The innate immunity does not has "immunity memory" and does not build up with experience. It is responsible for the first line of defense, reacting vigorously and with full force at the first signs of foreign bodies. It is largely active on the skin and mucosal surfaces in the body. This type of immunity was the first to evolve with living organisms.

The adaptive or acquired immunity is gradually build over the years after your birth, as it interacts with your environment. It can adapt to different pathogens (via antigens) to better attack them specifically. Has two adaptive mechanisms: cell-mediated immunity and humoral immunity.

The adaptive immune system begins to build up from the moment you are born up until about 6 years of age. By that time, it has build all antigens and antibodies specific to your habitat. That is why people living in different geoclimatic environments have different adaptive immune systems, adapted to the specific pathogens found in their environment. That is why, for instance, Indians can drink form the river Ganges without having any problems with the water, whereas if a foreigner drinks from it he or she will suffer from GI infections caused by the pathogens found in the water. The adaptive immune system is also targeted by vaccines.

For this reason, because the adaptive immune system develops in early age, it is best if antibiotics are avoided to be given in that tender period. With the adaptive immune system, the probiotic flora in the GI tract also gradually colonize the guts and if antibiotics are administered to young children too often, they can seriously interfere with the optimal development of their immune systems.

The most important element in being well and having strong health is your immune system. If it doesn't function properly, a myriad of health problems develop, including auto-immune disorders, chronic infections and various health conditions that seem to have no cause. The cause is an improperly functioning immune system.

Read more on:

Yeast infections

Urinary Tract Infections

Chronic Fatigue

AHCC as powerful immune system booster

A few education websites on the immune system:


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    • Inspiration88 profile image

      Inspiration88 6 years ago from this Galaxy

      Indeed, and a hell of a spiral it can be. I have also noted a seeming connection between blood types and the ability of different people to cope with internal infections (such as yeasts) resulting from weakened immune system. I, for instance, found it completely impossible to strenghten my immune system and cope with yeast without implementing some major lifestyle changes (in diet) and herbal supplements. I am blood type O. While other women also get such infections, but somehow recover way faster (I know two of them who are blood type A).

    • cangetthere profile image

      Paula 6 years ago from New Zealand

      Thanks for the information on the immune system I now understand it a bit more.It can be a spiral down when things go wrong with your health.Good reading thankyou