Elements in the Human Body and What They Do

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Element Chemistry of Your Body

Nearly all of the human body consists of only 6 elements. Of course, those other elements are vital, too!
Nearly all of the human body consists of only 6 elements. Of course, those other elements are vital, too!. Youst / Getty Images

99% of the mass of the human body is made up of only six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Every organic molecule contains carbon. Since 65-90% of each body cell consists of water (by weight), it isn't surprising that oxygen and hydrogen are major components of the body.

Here's is a look at the major elements in the body and what these elements do.

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Oxygen - Most Abundant Element in the Body

65% of body weight consists of oxygen. While gaseous oxygen is transparent, liquid oxygen is blue.
65% of body weight consists of oxygen. While gaseous oxygen is transparent, liquid oxygen is blue. Warwick Hillier, Australia National University, Canberra

 Oxygen is present in water and other compounds.

Oxygen is necessary for respiration. You will find this element in the lungs, since about 20% of the air you breathe is oxygen.

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Carbon - Present in Every Organic Molecule

18.6% of body mass is carbon. Carbon takes many forms, including charcoal, graphite, and diamond.
18.6% of body mass is carbon. Carbon takes many forms, including charcoal, graphite, and diamond. Dave King / Getty Images

Carbon is found in every organic molecule in the body.

Carbon is ingested in food the food we eat and in the air we breathe. Carbon accounts for 18.6% of the total mass of the human body. We even expel carbon as a waste product when we exhale in the form of carbon dioxide.

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Hydrogen - Third Most Abundant Element in the Body

9.7% of body weight consists of hydrogen atoms, the stuff from which stars are made.
9.7% of body weight consists of hydrogen atoms, the stuff from which stars are made. Stocktrek / Getty Images

Hydrogen is a component of the water molecules in the body, as well as most other compounds. 

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Nitrogen - Fourth Most Abundant Element in the Body

3.2% of body weight is nitrogen. Liquid nitrogen looks like boiling water. Nitrogen gas is the most abundant element in air.
3.2% of body weight is nitrogen. Liquid nitrogen looks like boiling water. Nitrogen gas is the most abundant element in air. Science Photo Library / Getty Images

Nitrogen is a component of proteins, nucleic acids, and other organic compounds.

Nitrogen gas is found in the lungs, since most of the air you breathe consists of this element. Nitrogen can be used from air, though. You need to eat foods that contain it to obtain this element in a usable form.

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Calcium - Fifth Most Abundant Element in the Body

Calcium is a soft grayish metallic element, although it is seen as part of compounds in nature.
1.8% of body weight is the element calcium. Calcium is a soft grayish metallic element, although it is seen as part of compounds in nature. Tomihahndorf, Creative Commons License

Calcium is a major component of the skeletal system. It is found in bones and teeth.

Calcium is also found in the nervous system, muscles, and the blood where it is integral in proper membrane function, conducting nerve impulses, regulating muscle contractions, and blood clotting.

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Phosphorus Is Critical in the Body

White Phosphorus Sample
1.0% of body weight is phosphorus. White Phosphorus Sample. W. Oelen

Phosphorus is found in the nucleus of every cell.

Phosphorus is part of nucleic acids, energy compounds, and phosphate buffers. The element is incorporated into the bones, combines with other elements including iron, potassium, sodium, magnesium and calcium. It is necessary for sexual function and reproduction, muscle growth, and to supply nutrients to the nerves.

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Potassium Is an Ion in the Body

Potassium is a metal, although it exists in compounds and ions in the human body.
0.4% of body mass is potassium. Potassium is a metal, although it exists in compounds and ions in the human body. Justin Urgitis, www.wikipedia.org

Potassium primarily is found in the muscles and nerves as an ion.

Potassium is important for membrane function, nerve impulses, and muscle contractions. Potassium cations are found in cellular cytoplasm. The electrolyte helps to attract oxygen and remove toxins from the tissues.

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Sodium Is Vital to the Human Body

Sodium metal chunks under mineral oil.
0.2% of the human body consists of sodium. Sodium metal chunks under mineral oil. Justin Urgitis, wikipedia.org

Sodium is essential for proper nerve and muscle function. It is excreted in perspiration. 

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Chlorine Is an Ion in the Body

0.2% of the human body is chlorine. The element chlorine is a yellow liquid and greenish-yellow gas.
0.2% of the human body is chlorine. The element chlorine is a yellow liquid and greenish-yellow gas. Andy Crawford and Tim Ridley / Getty Images

Chlorine aids in cellular absorption of water. It is the major anion in body fluids.

Chlorine is a part of hydrochloric acid, used to digest food. It is involved in proper cell membrane function.

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Magnesium Is in Enzymes

0.06% of body weight is magnesium, a metal.
0.06% of body weight is magnesium, a metal. Andy Crawford & Tim Ridley / Getty Images

Magnesium is a cofactor for enzymes in the body.

Magnesium is needed for strong teeth and bones.

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Sulfur Is in Amino Acids

0.04% of the human body is sulfur. Sulfur is a yellow nonmetal.
0.04% of the human body is sulfur. Sulfur is a yellow nonmetal. Clive Streeter / Getty Images

Sulfur is a component of many amino acids and proteins.