The biological defenses of humans and other higher organisms are called the immune system, derived from the Latin word immunis for free or unaffected. It is a complex and adaptive endogenous defense that can flexibly adapt to various internal and external threats. It is made up of organs such as the liver, cell types and molecules. They work together to ward off various threats. The system has to learn this cooperation and the individual reactions at a young age and continue to train it.
Each infection survived expands and improves the possibilities of the immune systems.
Various defense mechanisms develop in response to harmful unicellular microorganisms (e.g. plasmodia), multicellular parasites (e.g. tapeworms) or typical pathogens such as bacteria and viruses. In the event of danger, scavenger cells, e.g. phagocytes, come into action first. Destroying all foreign bodies which they can identify. Also informing the specific immune system when they see viruses. Specific immune cells, e.g. T-lymphocytes, make contact with the viruses and develop suitable antibodies for each individual virus type. If these are formed in sufficient numbers, the human being is immune to a specific pathogen. If this enters the body again, the so-called killer cells are notified and destroy it immediately.
Colds and mild infections are helpful in developing and training the immune system. They prepare it for dangerous pathogens such as flu viruses.
Encountering various foreign bodies is not only an exercise, but also keeps the immune system from overreacting to harmless substances, e.g. bee pollen. One of the various weapons of the body’s defenses is, for example, the protein TNF-alpha. He inhibits the urge to move and causes exhaustion in order to force the affected person to rest.
Fever is also an important defense reaction. That prevents viruses from depositing their genetic material in body cells and thus from multiplying and spreading.
The immune system not only turns against external threats, but it is also able to break down body cells that have become defective or have died. In that way she defend the healthy organism.
The human immune system is a network in which various cells and organs of the body work together to protect it through a variety of functions, mechanisms and reactions.