Body processes

Immunity – Function, Task & Diseases


The term immunity comes from Latin and means “freedom from disease”. From a medical point of view, this means that an organism, such as humans, is immune to external attacks by pathogens. Even simple organisms have what is called an immune system . This is similar to the protective mechanisms that plants also have. Vertebrates, including humans, have a much more complex immune system than plants and simple organisms.

What is the immunity?

Immunity manifests itself in different forms in people. Genetically determined immunity protects those affected against certain viruses for life . It is most likely caused by a mutation in the genome. For example, around 0.5% of all people have natural immunity to the HI virus and there is also an innate resistance to leprosy .

Acquired immunity, on the other hand, develops after a single infection with a pathogen. A classic case is chickenpox , which is considered a childhood disease, but can also occur in adults. In most cases, the disease occurs only once in a lifetime, as people become immune to the virus after the onset of the disease. Only in exceptional cases, i.e. when the body’s own defenses are severely damaged, do those affected get chickenpox several times.

Acquired immunity to an antigen can also result in cross-immunity . When this happens, the body develops resistance to a related antigen.

Newborns have an innate but only temporary immunity. In their first months of life, the so-called nest protection protects them from some diseases to which their mother is immune. However, the natural protection acquired through the baby’s bloodstream wears off after some time and disappears completely after about nine months. After loss of natural immunity, vaccinations offer protection against pathogens. A vaccination creates a natural immunity that needs to be refreshed after a few years.

Function & task

Immunity to external attacks has secured human life since the dawn of history. Without immunity and disease resistance, people would fall prey to seemingly harmless diseases, such as the common cold . Only through immunity is it possible for people to eat and drink water.

Every everyday action demands the immune system and natural processes such as breathing or touching everyday objects, plants and animals require a certain degree of immunity against harmful substances. Without this vital defence, pathogens and microorganisms can penetrate the human body and cause tissue damage. In addition, the immune system protects people from endogenous attacks that can be triggered, for example, by defective or dead cells .

Human immunity is a complex protective mechanism granted by the interaction of various barriers. The greatest external barrier of man is the skin , which prevents the penetration of harmful substances. Other external barriers that support immunity include the mucous membranes , respiratory tract , eyes , oral cavity , and urinary tract.

The intestines are often said to have a special function in the body’s own defences . At the cell level, the granulocytes found in the bloodstream and the macrophages , known as giant cells, guarantee natural protection against invaders and also promote the breakdown of toxic substances. Other active substances in the body’s own defenses include natural killer cells , dendritic cells , T helper cells and antibodies . Without the interaction of these mechanical barriers, cells and messenger substances , even everyday diseases and infections become a deadly risk.

Diseases & Ailments

Like immunity, diseases and disorders of the immune system can either be congenital or acquired. Congenital disorders of the immune system are very rare and in many cases are fatal in infancy and early childhood. The therapy turns out to be difficult because only treatment with stem cells from another person is considered to be promising. Another way to protect sick people is to try to keep them away from sources of infection.

An acquired immune disease that has already claimed the lives of millions of people is the HI virus. In all likelihood, the virus originated in African chimpanzees and was first transmitted to humans in the first half of the 20th century. It eventually evolved into pandemic in the 1980s .

Transmission occurs most commonly through blood transfusions , punctures with infected needles , and unprotected anal and vaginal intercourse . The virus is transmitted through the bodily fluids blood , semen , breast milk and vaginal secretions and enters the bloodstream of those affected via open wounds or mucous membranes. After infection, the affected people suffer from flu-like symptoms. The actual disease often remains undetected for several years before the deadly AIDS disease breaks out.

Another type of immune disease are autoimmune diseases , which also include allergies . In the case of an autoimmune disease, the organism fights the body’s own tissue, as this is regarded as a foreign body. The exact cause of autoimmune diseases has not been finally clarified. However, a combination of a congenital and an acquired defect in the immune system is assumed.

A well-known autoimmune disease, for example, is the inflammatory bowel disease Crohn’s disease , which most commonly occurs between the ages of 15 and 35 years. Sweden currently has the highest incidence rate. The metabolic disease diabetes mellitus type 1 is also counted among the autoimmune diseases. Other diseases include chronic gastritis , Hashimoto’s thyroiditis , narcolepsy , also known as sleeping sickness , rheumatoid arthritis and the widespread gluten intolerance celiac disease .

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.