Electricity (from the Greek. elektron - amber - the set of phenomena connected with the existence and interaction of electric charges.
In substance, there are two types of elementary electric charge: positive related to nuclear particles - protons, and negative in the form of electrons surrounding the nucleus of atoms. Depending on the mobility of charges in the amount of mass all bodies are divided into three main groups: conductors, semiconductors and non-conductor, or dielectrics. In the conductors are moving charges in the form of free electrons or ions. In semiconductors (see) charges acquire mobility only under certain conditions. In dielectrics moving charges not.
Body tissues are partly to the guides in part to the dielectrics. Organic substances, which form a dense tissue, clean and dry are dielectrics. However, all of the tissues in the body impregnated or wash liquids, consisting of the solutions of electrolytes and are therefore assigned to the conductors. The best guides are the cerebrospinal fluid, plasma of blood and muscle tissue; tissues of internal organs, nerve and brain, fat and connective relatively poor conductors. The insulators can be attributed corneal layer of the skin, fabric ligaments and tendons and bone, devoid of periosteum.