Why our bodies need a metal element?

I heard that our bodies need a little metal element. However, our bodies consist mainly of organic compounds. Why our bodies need a metal element? What elements of metal work in our body?
Answer:Dr. Eiichiro Ochiai, someone who is studying chemistry bioanorganik, willing to answer the question above. In short, he talked about the general term needs of the metal elements in biological organisms and describe the usefulness of metal elements with one element of the most widely used metal, iron (Fe). So the following story entitled "A Story About Iron" (© Eiichiro Ochiai).As living beings, we consist of, chemically, kebanykan organic compounds such as proteins, nucleic acids, carbohydrates, vitamins and the like. Organic compounds composed of carbon atoms (C), hydrogen (H), oxygen (O) and nitrogen (N). A number of organic compounds can also contain sulfur (S) or phosphorus (P). That's it, nothing else. Can we live well only with organic compounds? Most people know that the answer is no. Bones and teeth are made of calcium compounds (Ca), which is classified as "inorganic". Blood contains iron (Fe), an inorganic element. Everyone knows that we need a salt (sodium chloride, NaCl), although they do not know why. In fact, about 30 elements known to be required for the functioning of living beings. As you already know, only there are 100 elements that exist in nature, and one third of these elements is essential for living things. An important element of which is (other than those already mentioned): magnesium (Mg), silicon (Si), potassium (K), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), molybdenum (Mo), iodine (I), selenium (Se), nickel (Ni), and boron (B). A new research field is now being developed, which studies the role of different elements and the role of these compounds in biological systems; science is called "chemical bioanorganik". Too long if this is discussed in the forum this time: therefore, I chose a particular element and describe the field of science called chemistry bioanorganik. The first section "Formation of Iron element" is not an appropriate topic of chemical bioanorganik, but added here to tell you about a very important role of iron.
I'm sure everyone is familiar with the metal iron. Cars and machinery mostly made of iron. Iron is one of the elements that are available are very abundant in nature and the metal of the most interesting, as one of the crucial element for living beings. Here is the story about the iron.