The skin, with a surface area of some 1,5 to 2 square metres and a weight ranging from 3,5 to 10 kg, is our biggest organ. The skin's tasks and functions are very varied and have a direct influence on the entire body. Life is in acute danger when one third of the skin's surface is destroyed by, e.g. burns. Our skin forms a mechanical and chemical protective wall against exterior influences. It is part of the immune system and controls our

thermoregulation. Among our sensory organs, the skin is the one with the most nerves, allowing us to touch and sense our environment.

Connected to our externally visible skin are mucous membranes that dress our inner moist body surface, the hollow organs. To be counted among these are the mucous membranes of the nasal and throat areas, the breathing organs and those of the gastrointestinal tract, as well as of the urinary tract.

Under normal circumstances, the skin as well as the mucous membranes are densely populated by a large variety of microorganisms. Apart from numerous harmless species, there are also those which may possibly trigger illnesses if allowed to spread excessively. In a healthy person's natural skin flora microorganisms are well-balanced, so that an unwanted spread of pathogens can be successfully suppressed.