Immune System Diseases - Immune System Function

What is the immune system?

The biological immune system of higher organisms is known as immune system that prevents tissue damage by pathogens. It removes stains microorganisms, foreign substances in the body and is also able to destroy the body's own cells that have become corrupted. The immune system is a complex network of different organs, cells and molecules and the central object of research of immunology.

The immune system has a great importance for the physical integrity of living beings, because virtually all organisms are constantly exposed to the influences of the lively environment; some of these influences are a threat: If harmful micro-organisms enter the body, this can lead to malfunctions and diseases. Typical pathogens are bacteria, viruses and fungi, as well as single-celled (E.g. protozoa such as Plasmodium) or multi-cellular parasites (E.g., tapeworms).

Also changes inside the body can threaten the existence of a living being: If normal body cells in the course of time lose their healthy function, then they usually die and must be reduced (necrosis) or build themselves from (apoptosis). In rare cases, they can also morbidly degenerate and lead to the formation of cancer.

All living creatures have protection functions. Even simple organisms have a defense mechanism such as this, or the so-called innate immune response. She arose very early in the phylogeny of organisms and has been maintained since then largely unchanged. In addition, the vertebrate animals developed a complex, adaptive, so-called adaptive immune system, which protects them more effective against pathogens.

The herbal immune response has similarities with the innate immune response in animals. Plants have no adaptive immune response, so no T cells or antibodies.

Components of the immune system

The components of the immune system are

-Mechanical barriers that prevent the ingress of pests
-Cells, such as granulocytes, natural killer cells (NK-cells) or T-lymphocytes. They are summarized in part to specialized organs (lymphatic system).
-Proteins that act as messengers or for defense against pathogens
-Psychological immune factors.

Mechanical and physiological barriers
The mechanical and physiological barriers of the body are the first line of defense against pathogens. They ensure that only the pathogens can not penetrate into the body, or leave it as quickly as possible:

-Skin - outer layer as a barrier, sebum, sweat and normal tumbuhan as growth inhibitors of pathogenic microorganisms
-Mucous membrane - binding function of the mucus
-Eyes - removal function of tears, antimicrobial enzyme lysozyme fights microorganisms
-Respiratory System - binding function of the mucus, removal function of the cilia
-Oral cavity - antimicrobial enzyme lysozyme in saliva combat microorganisms
-Stomach - stomach acid (hydrochloric acid contains) and protein-degrading enzymes destroy almost all bacteria and microorganisms
-Intestine - defense against infection by bacteria present (intestinal flora), removal function by continuous discharge and the so-called gut-associated immune system (GALT Associated Lymphoid Tissue = Good) and antibacterial proteins
-Urinary tract - removal function by constant Harnaussp├╝lung and osmotic effects of high urea concentration

Cellular components
The immune system cells circulate in the blood vessels and lymphatics and are found in the tissues of the body. Penetrates pathogens into the body, the immune cells to fight it. Neutrophils, monocytes / macrophages and dendritic cells can destroy the pathogen itself or controlled by the production of immunomodulatory cytokines and the immune response of the organism and attract other immune cells to the site of inflammation such as by absorption and digestion (phagocytosis).

Granulocytes (from Latin granuloma. Granules) make up the bulk of the white blood cells (leukocytes). You can leave the bloodstream and migrate into the tissue. Granulocytes have in their cytoplasm numerous vesicles (vesicles or granules called) containing aggressive substances with which pathogens can be rendered harmless. Other substances (eg, histamine) play a role in the inflammatory response and allergies. The different groups of granulocytes are classified according to their staining reaction in the Giemsa stain.

The neutrophils make up 40 to 50 percent of circulating leukocytes. Activated by cytokines, which are discarded from the site of infection, they migrate from the blood vessels into the affected tissue. The granules of neutrophils contain, among other acid hydrolases, defensins (30% of the content), myeloperoxidase and proteases, such as elastase, collagenase, neuraminidase and cathepsin G. This "cocktail" allows neutrophils to clear a path through the tissue and penetrate into the bacteria. There they are able to destroy pathogens (such as bacteria) including through phagocytosis.

Maturing and aging of the immune system

The immune system is not yet effectively fight in the womb and after birth in a position to pathogens. The fetus and infant is therefore dependent on the protection by maternal antibodies (so-called. Nest protection), it receives via the placenta or breast milk. In many mammalian antibodies can not cross the placenta, the picture will be on the antibody-rich colostrum. Since the transplacentalen antibodies in the baby's blood are degraded with a half-life of approximately 4 weeks, protects these passive immunization, only 3 to 4 months prior infection by most germs. Breastfeeding by non-specific IgA, which attach to the mucosa, a little longer protect / intestinal bacteria from infections of the upper respiratory tract and stomach.

In the first months of life the immune system to prepare for the defense of disease cells begins. This is done by a process of negative selection; That is, the body produces first through random genetic recombination many millions of different immune cells, each of which can recognize a different antigen. Following such cells are eliminated, which would cause an immune response to endogenous structures (This process is under the term self-tolerance together). In the case of T-cells, this is done in the thymus, maturation site of the T-cells. Here, the T cells differentiate into different types (such as CD4 + and CD8 + cells) and are then confronted with endogenous substances. If a T-cell carries a matching receptor and binds to the body's structure, dies from the T cell. The immune system learns "foreign" from "self" to distinguish.

With advancing age, the susceptibility of humans to diseases and other disorders increases again. This is mainly because that the age reduces the formation of B and T lymphocytes. In addition, the immune cells are generally less active, which leads to a weakening of the immune system, associated with an increased risk to infections and cancer.

Disorders and diseases of the immune system

As with all biological systems can make mistakes as also reflected in the immune system. Thus, the immune system may lose its ability to respond to pathogens or endogenous cells to respond appropriately: depending on the cause of the disturbance occurs either too weak or lack of immune response or to excessive, excessive immune reaction. The cells of the immune system can become malignant and cause cancer. Likewise, an influence of depressive disorders, stress and other mental illnesses is suspected on the immune system.

Lack of individual components of the immune response or do these not work properly, the immune system can not effectively fight and even diseases that are usually harmless, can be life-threatening gradients pathogens. Immune deficiency may be congenital or acquired:

-The severe combined immunodeficiency (SCID) is a group of congenital immunodeficiencies, which are characterized by impairment of both the cellular immune response and the humoral immune response, hence "combined" the name.
-The acquired immunodeficiency AIDS is caused by the HIV virus that successfully evades the immune system by the infection of T-helper cells. However, more and more immune cells are destroyed by the multiplication of the HIV virus, so that in most cases after a few years, an increasing incubation immune deficiency occurs and the number of infections and tumors increases.
-Neutropenia or agranulocytosis even can be caused by autoimmune disease caused by side effects of certain medications (eg. As cytostatics) or and results mainly in mucosal inflammation and so-called opportunistic infections by otherwise harmless pathogens.
-Other congenital immunodeficiencies are: Behcet's disease, DiGeorge syndrome, selective immunoglobulin A deficiency and the Wiskott-Aldrich syndrome, in each of which a certain proportion of the immune system is impaired.

Cancers of the immune system
The cells of the immune system can become malignant and lead to cancers that usually affect the whole body and play, especially in the organs of the immune system and lead to the decrease in the immune response and displacement of normal hematopoiesis in bone marrow. Due to the large number of different cells and their precursors, there are a variety of different cancers with very different symptoms and course of the disease, which can be roughly divided into two groups, however: If the cancer of progenitor cells in the bone marrow, we speak of leukemias can be acute or chronic. Malignant tumors of the lymph nodes is called lymph node cancer or malignant lymphoma.

On the other hand, is a therapeutic approach for cancer, cancer immunotherapy, the activation of the immune system against tumor cells.

Other weaknesses of the immune system
-Viruses are wrapped in a layer that is not the body recognizes as foreign (eg, a layer of lipids), so they are not visible.
-In contrast to tumor cells, pathogens do not cause inflammatory reactions, so it does not come to an activation of the immune response. Some tumors have the ability to disguise themselves literally. If no tumor-associated antigens (TAA) are formed by the cancer cells, the immune system, therefore, does not recognize the cancer cell and leads to cancer growth and / or metastasis.
-The immune system protects According to present knowledge no prior prions (infectious proteins), but seems - on the contrary - to play a role in the spread of prion disease. Thus, for example, were in an experiment, mice with defective immune system immune introduced prions, while animals developed disease with functioning immune system.

Effects on the immune system

In an intact immune system is called immune competence. The defense function can be affected positively or negatively in several ways:

Strengthens the immune system
The phrases "strengthen the immune system" and "strengthening the defenses" are often used as a slogan in the advertising of dietary supplements, functional foods and alternative medical remedies. So also takes the fasting cure lay claim to boost the immune system. The duduk perkara here is a lack of medical definitions of what is meant by "strengthening". Such references to general, non-specific benefits of a product are under EU law, according to Article 10, paragraph 3 of the Health Claims Regulation prohibited unless they are not an approved by the European Food Safety Authority specific health claim is attached. For inclusion on the positive list of approved information must the way in which the product acts on the immune system, and indicated the effectiveness of scientific proof.

A healthy and strong immune system can help people to fight against various pathogens and sometimes thus to prevent a disease outbreak or alleviate disease symptoms, or to shorten the course of disease.

As a basis for a healthy immune system balanced human diet that contains all the substances necessary for the organism, such as minerals (especially iron, zinc and selenium) and vitamins, and sufficient sleep are valid; Furthermore, the long-lasting (chronic) stress should be avoided.

As appropriate measures to boost immune function are valid regular exercise, especially sporting endurance training, as well as regular Resilience, for example, by use of sauna and Kneipp showers. Psychotherapeutic process, especially methods that stress management can strengthen the immune system. The clinical hypnotherapy has developed suggestive methods to support the general immune system and for the treatment of individual immune diseases.

Sunlight and immune system
Sunlight can boost the immune system. Already more than 100 years ago, the daily sun was an integral part of the treatment of tuberculosis (although in the absence of antibiotics, which were discovered in 1930 and is being tested in humans after 1940). The research could represent the underlying mechanism: Certain immune cells have on their surface a so-called Toll-like receptor; This is activated when a bacterial infection and causes the immune cell to produce a precursor of vitamin D (25-hydroxyvitamin-D). Yet the same cell forms amplified from another type of receptor, which is specialized in the detection of vitamin D. The sunlight converts the vitamin D precursor into the active vitamin D, which is now attached to the receptor. Thus, the defense cell is stimulated to form the antibacterial cathelicidin. The relationship also explains why people with dark skin infections such as tuberculosis of the skin are particularly susceptible: In their blood are found generally much lower amounts of the vitamin D precursor, with additional vitamin D supplements to strengthen the immune system to can easily compensate for deficiency. (Documents / Source missing)

A weakening of the immune system may be a consequence of the immunosuppressive effect of the UV-B rays, which interferes with T-cell-dependent immune response. An excessive UVB exposure of the skin promotes the development of malignant skin tumors such as basal cell carcinoma and squamous cell carcinoma [20] and reduces the defense against pathogens such as bacteria, fungi or viruses significantly. Caused by parasitic diseases such as leishmaniasis, schistosomiasis and malaria run harder and longer after UV exposure.

Vaccination is a way to strengthen the immune system and a preventive measure against certain infectious diseases. In active immunization, the most common form of vaccination, the immune system is stimulated to form an immune competence without triggering the disease itself. For this purpose attenuated pathogens, dead agents or of certain typical proteins (proteins) and sugar molecules so introduced fragments of the pathogen as a vaccine into the body. The reaction of the organism to these antigens leads to the formation of specific antibodies and memory cells which continue to circulate in the blood and the lymphatics, whereby the protection against these antigens is maintained long. If the body comes in contact again with the pathogen, he has carried the memory cells much more efficient and faster immune response available to combat the pathogen before it comes to a disease.

The immune system damaging factors
Apart from aging, there are other factors that can damage and degrade the function of the immune system. These include a strong adverse health effects due to previous damage such as chronic diseases, drug immunosuppression, such as organ transplantation, drug abuse (including nicotine and alcohol), malnutrition and related under-supply with vitamins and trace elements, an unhealthy or poor diet, the inclusion of environmental toxins from the environment, the action of ionizing radiation, prolonged stress, lack of sleep, lack of exercise and excessive exposure to cold in the sense of a longer cooling down or even hypothermia (hypothermia). In sports, it comes after exhausting exercise temporary impairment of the defense function, which is known as open-window phenomenon. A combination of several factors may of course be an increased burden on the immune system.

Psychological factors such as stress affect the immune system. Stress causes general physiological processes are shut down, which require energy to a large extent, but not required for short-term survival. This includes the immune system. The immunosuppressive effect of stress is conditioned on the release of glucocorticoids (cortisol in humans in particular) from the adrenal cortex, which in turn triggered by adrenocorticotropic hormone from the anterior lobe of the pituitary gland, which in turn inhibits the production of cytokines. In the case of chronic stress leads to a limitation of the adaptive immune system, which exerts its function via sheltered T and B cells.

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