Written by Laura Jang (Korea International School '19)
Edited by Chloe Cheng (Venice High School '21)
━━ August 2st, 2018 ━━
Essential Elements of the Human Body
Since 9000 BC, when copper was first discovered, scientists have found 118 elements on Earth. Some elements have been known for thousands of years, like copper, antimony, arsenic, carbon, iron, gold, lead, mercury, silver, sulfur, and tin, but it is not known who first discovered them because it had been long ago. The first known person to discover a new element was Hennig Brand, who discovered phosphorus in 1669. Examples of elements vary from common elements, such as hydrogen and oxygen, to rare elements, such as praseodymium and yttrium. An element is “a substance that cannot be broken down by chemical means.” It consists of only one type of atom and is organized on the Periodic Table by its atomic number. A Russian chemist named Dmitri Ivanovich Mendeleev created a periodic table similar to today’s Periodic Table of Elements. Many scientists became interested in the elements themselves and frequently questioned, “Which elements are essential for human life?” Human bodies are known to contain at least 60 detectable chemical elements; however, most studies have proved only about 25% of those 60 elements participate in the healthy functioning of the human body.
Scientists have classified the essential elements into three main groups: bulk elements, macrominerals, and trace elements. The bulk elements are elements that primarily constitute our organs, muscles, and our diet; the daily intake requirement for humans is in tens of grams. These elements include oxygen, carbon, hydrogen, nitrogen, and sulfur. The next group of elements is called the macrominerals because they provide essential ions and form major structural components in the human body. These elements include sodium, magnesium, potassium, calcium, chlorine, and phosphorus. The six macrominerals are present in the body in smaller amounts—usually in grams—than the bulk elements, and therefore fewer amounts are required in the daily diet. The remaining essential elements are called trace elements. The trace elements are present in very small amounts, varying from a few grams to a few milligrams. Iron, silicon, zinc, copper, and lead are just a few examples of trace elements.
► Bulk Elements:
Oxygen (65% of body weight) is the most abundant element in the human body in a molecule form, water. Oxygen in its elemental form, O2, is required for all aerobic (relating to oxygen) organisms to use in cellular respiration. Thus, large amounts of oxygen are found in the lungs and in the bloodstream. Hemoglobin molecules in the blood bind to oxygen molecules from the inhaled air. Additionally, it acts as an electron acceptor agent, found in all four of the major organic molecules: proteins, carbohydrates, lipids, and nucleic acids. Oxygen is also used by mitochondria in cells to produce the energy molecule adenosine triphosphate, also known as ATP.
Carbon (18% of body weight) is the “backbone” of all life because it bonds with many elements, including itself, to form molecules and structures essential to all organisms. Considered the basis of organic chemistry, every single organic molecule in the human body contains carbon. Carbon bonds to itself to form chains and ring structures that are used as the basis for all metabolic reactions in the body.
Hydrogen (10% of body weight) is the lightest and the most abundant element in the universe. It rarely exists in its elemental form (H2), by itself, but is plentiful in molecules, bound up with other elements.
Nitrogen (3% of body weight) makes up the bulk of Earth’s atmosphere. Although nitrogen gas is found in the lungs (because air consists largely of nitrogen), humans get nitrogen from food, not inhaling. It is essential to amino acids and nucleic acids—thus to proteins, DNA, and genetic material. In the atmosphere, nitrogen is found in its elemental form (N2), which is unreactive. However, certain bacteria can transform N2 to a much more reactive form, NH4+, which is more frequently used biologically.
Sulfur (0.25% of body weight) exists in both its elemental form and compounds. It is necessary for life, for certain amino acids and enzymes contain sulfur. Sulfur forms bridges between different parts of a protein, giving protein its 3D shape. It is also a key element in biochemistry, reacting with certain microorganisms, such as archaea, methanogens (methane producing), and sulfur-reducing bacteria that use chemical sources of energy. For this reason, sulfur is an important element for astrobiologists and scientists who study the survival of such microorganisms that live around hydrothermal vents, which provide a habitat and an energy source for life.
Oxygen and hydrogen bond together to form water molecules. Water is an essential solvent for molecules that need to be dissolved in order to function. As an example of this, enzymes float in watery environments, or fluids, to speed up chemical reactions. Also, lipids can easily store energy and the sugars that will be broken down to produce it.
► Macrominerals:
Phosphorus (1% of body weight) helps connect individual units of DNA into a long chain. It is found in bones, teeth, nucleic acids, and energy molecules, such as ATP.
Calcium (1.4% of body weight) is mostly found in bones and teeth, where it is used to build strong structural compounds. However, the most important functions are muscle contraction and the regulation of proteins, for which it is used as an important ion.
Potassium (0.25% of body weight), one of the most important cations, is used in nerve conduction and regulating heartbeat.
Sodium (0.15% of body weight) is also an essential cation, and is used for nerve transmission and muscle function.
Chlorine (0.15% of body weight) an important anion, is used to transport the enzyme ATPase, which supplies energy for biochemical reactions. It is also used to make hydrochloric acid, the acid found in the stomach to digest food.
Magnesium (0.005% of body weight) is required for enzymes to function, binding to ATP and nucleotides.
►Trace Elements:
Many compounds of trace elements are toxic, and can even cause cancer, yet these elements are identified as essential elements because small amount of these trace elements can also be helpful and necessary in our bodies.
Iron was the first to be recognized as an essential element in the 17th century. Anemia, a “condition that develops when your blood lacks enough healthy red blood cells or hemoglobin,” was proven to be caused by an iron deficiency. It was often cured by supplementing the diet with the extracts of rusty nails!
Zinc is found throughout the entire body system, especially in muscle tissue. It also functions as a cofactor for certain enzymes involved in metabolism and cell growth.
Cobalt is an essential trace element for the human body, forming amino acids and neurotransmitters. Cobalt ions enter the body to bind with proteins, then get transported with blood to be stored in tissues and cells.
Out of 118 elements found today, human bodies can detect about 60 elements and out of those 60, only 25% are found to be essential. The scientists classified these elements into three groups: bulk elements, macrominerals, and trace elements, bulk being the most important elements. The elements participate in regulating our body systems or forming our body structures. Therefore, knowing these elements and their roles is important to stay healthy!
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Bibliography:
"1.8 Essential Elements For Life." Chemistry LibreTexts. N. p., 2014. Web. 2 Apr. 2018.
Al-Fartusie, Falah S., and Saja N. Mohssan. "Essential Trace Elements and Their Vital Roles in Human Body." Indian Journal of Advances in Chemical Science, vol. 127, no. 136, 25 May 2017, doi: 10.22607/IJACS.2017.503003. Accessed 8 Apr. 2018.
"Definition Of Element - Chemistry Dictionary." Chemicool.com. N. p., 2018. Web. 2 Apr. 2018.
Helmenstine, Anne. "Elements In The Human Body And What They Do." Science Notes and Projects. N. p., 2015. Web. 10 Apr. 2018.
"Key Requirements For Life On Earth – Six Elements | Fosdick's Astrobiology." Fosdicksastrobiology.com. N. p., 2018. Web. 10 Apr. 2018.
What Are The Major Chemical Elements Found In Cells In Biology?." Sciencing. N. p., 2018. Web. 10 Apr. 2018.
Pictures:
- https://wallpaper-house.com/data/out/5/wallpaper2you_79360.png
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To contact the author, email Laura Jang at ljjang19@student.kis.or.kr
To contact the editor, email Chloe Cheng at chloe.cheng03@gmail.com