The average 70 kg (150 lb) adult human body contains approximately 7 ×10 27 atoms and contains at least detectable traces of 60 chemical elements. Fluorine is used by a number of plants to manufacture toxins but only functions in humans as a local topical hardening agent in tooth enamel. One study has indicated bromine to be necessary to collagen IV synthesis in humans. Bromine is used abundantly by some (though not all) lower organisms, and opportunistically in eosinophils in humans. Some elements (silicon, boron, nickel, vanadium) are probably needed by mammals also, but in far smaller doses. In humans, arsenic is toxic, and its levels in foods and dietary supplements are closely monitored to reduce or eliminate its intake. Some of these elements are thought to be simple common contaminants without function (examples: caesium, titanium), while many others are thought to be active toxins, depending on amount (cadmium, mercury, lead, radioactives). Not all elements which are found in the human body in trace quantities play a role in life. All of the mass of the trace elements put together (less than 10 grams for a human body) do not add up to the body mass of magnesium, the least common of the 11 non-trace elements. The remaining elements are trace elements, of which more than a dozen are thought on the basis of good evidence to be necessary for life. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. Pie charts of typical human body composition by percent of mass, and by percent of atomic composition ( atomic percent).Ībout 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. In terms of cell type, the body contains hundreds of different types of cells, but notably, the largest number of cells contained in a human body (though not the largest mass of cells) are not human cells, but bacteria residing in the normal human gastrointestinal tract.Įlements The main elements that compose the human body molecules (including water) can be summarized as CHNOPS. In terms of tissue type, the body may be analyzed into water, fat, connective tissue, muscle, bone, etc. This can be done in terms of the chemical elements present, or by molecular type e.g., water, protein, fats (or lipids), hydroxylapatite (in bones), carbohydrates (such as glycogen and glucose) and DNA. Not to be confused with Human anatomy or Body composition (physical fitness).īody composition may be analyzed in various ways.
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