The immune system is an endogenous defense system. Without an immune system, the human body would be vulnerable to harmful environmental conditions and harmful changes in the body. The immune system is thus an endogenous mechanism that is vital.

Definition, meaning and function of the immune system

Plasma cells are cells of the immune system and are used to produce and produce antibodies. Orange: plasma cells, white: antibodies. Click to enlarge.

The immune system consists of two mechanisms whose task is to ward off pathogens and foreign substances and thus to maintain the health of the body. These defense mechanisms are on the one hand the specific, ie acquired immune defense, on the other hand the nonspecific, as innate immune defense. These two main systems complement each other in their various functions.

The main function of the immune system is to successfully ward off pathogens and foreign substances entering the body from outside. In addition, the immune system can recognize and eliminate pathological and altered body cells. A reaction of the body to its own immune system is inflammation. They arise when the defense system tries to remove foreign substances or damaged body cells.

In some pathogens, the immune system gives the body after the successful control of harmful substances immunity, thus protecting against new diseases. In addition, the immune system can kill tumor cells. Sometimes the immune system can also react too strongly to certain substances.

Allergies are an example of an excessive immune reaction to certain substances. Some functions of the immune system are innate. Others are acquired. The immune system is a very complex body-own system, which can be impaired and disturbed by many influences in its functions. Many diseases can be caused by disorders of the immune system.

Disorders & Diseases

The immune system does not always work completely trouble-free. It can happen that it comes to excessive immune reactions or also to a reduced immune defense. If it comes to an exaggerated immune response to certain substances, this can be expressed in allergies.

In the case of allergies, the body mostly reacts to substances that are foreign to the body, which would not elicit any noteworthy defense reactions in the case of a normally functioning immune system. Find diminished or no immune reactions instead, this manifests itself in so-called immune deficiency diseases. A weakened immune system can either be innate or develop over time. A weakened immune system is more likely to cause infections.

Pathogens and foreign substances that enter the body from outside can spread through the diminished or absent immune responses in the body. Another disorder in the immune system can manifest itself in the so-called autoimmune diseases. A normally functioning immune system not only reacts to foreign substances with defense reactions, but also recognizes the body's own cells and structures, which are in some way altered or pathological.

For example, an intact immune system can also find and destroy tumor cells. In an autoimmune disease, however, in the worst case, the defense reactions of the immune system are aimed at healthy body cells and destroy them. It is also possible that the recognition of altered endogenous structures is disturbed. In this case, for example, it can lead to the development of cancer. The immune system is also responsible for the rejection of transplanted organs.

Inside & outside influences

Disorders of the immune system can be attributed to external as well as internal influences. In addition, a distinction is made between innate and acquired immune system disorders. An innate immunodeficiency is based on genetic defects. In a genetic defect, the carriers of the genetic material are damaged.

As a result, the functioning of the immune system is disturbed. Only one function of the immune system or even several functions can be affected by the disorder. Acquired immune disorders are usually based on external influences. Thus, certain diseases such as HIV infection can cause a disorder in the immune system.

In addition, the functions of the immune system are significantly influenced by factors such as diet or stress. A lack of nutrition, in which certain minerals or vitamins are inadequately or not absorbed, the immune system can be significantly disturbed.

Excessive stress factors can also have negative effects on the immune system. In addition to these external influences, an acquired immune deficiency can also be triggered by the body's own, ie internal, factors. In particular, the intestinal flora as well as the entire physical state has an influence on the immune system and may possibly weaken it.

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