Free radicals

A free radical is a chemical species having one or more unpaired electrons, an unpaired electron being one that is alone in an orbital. These radicals are capable of reacting promiscuously with any molecules with which they come in contact. They can either react with another radical or with another nonradical molecule. Free radicals are continuously produced by the body's due to the normal use of oxygen for metabolizing fats, proteins, and carbohydrates for energy. About 5% or more of the inhaled O₂ is converted to ROS.