Composition of the human body

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File:Two pie graphs about the composition of the human body.png
Pie charts of typical human body composition by percent of mass, and by percent of atomic composition (atomic percent)

Body composition may be analyzed in various ways. This can be done in terms of the chemical elements present, or by molecular structure e.g., water, protein, fats (or lipids), hydroxyapatite (in bones), carbohydrates (such as glycogen and glucose) and DNA. In terms of tissue type, the body may be analyzed into water, fat, connective tissue, muscle, bone, etc. 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 cell) are not human cells, but bacteria residing in the normal human gastrointestinal tract.

Elements

The main elements that comprise the human body (including water) can be summarized as CHNOPS.
File:201 Elements of the Human Body.02.svg Element Symbol percent
mass 		percent
atoms
Oxygen O 65.0 24.0
Carbon C 18.5 12.0
Hydrogen H 9.5 62.0
Nitrogen N 2.6 1.1
Calcium Ca 1.3 0.22
Phosphorus P 0.6 0.22
Sulfur S 0.3 0.038
Potassium K 0.2 0.03
Sodium Na 0.2 0.037
Chlorine Cl 0.2 0.024
Magnesium Mg 0.1 0.015
All others < 0.1 < 0.3
File:Element abundance human body ppm chart.svg
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm

About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, & magnesium. All 11 are necessary for life. 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.[1] 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.

Other elements

Not all elements which are found in the human body in trace quantities play a role in life. 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). In humans, arsenic is toxic, and its levels in foods and dietary supplements are closely monitored to reduce or eliminate its intake.[2]

Some elements (silicon, boron, nickel, vanadium) are probably needed by mammals also, but in far smaller doses. Bromine is used by some (though not all) bacteria, fungi, diatoms, and seaweeds, and opportunistically in eosinophils in humans. One study has indicated bromine to be necessary to collagen IV synthesis in humans.[3] Fluorine is used by a number of plants to manufacture toxins but in humans its only known function is as a local topical hardening agent in tooth enamel.[4]

Elemental composition list

Template:Main article The average Script error: No such module "convert". adult human body contains approximately Script error: No such module "val". atoms and contains at least detectable traces of 60 chemical elements.[5] About 29 of these elements are thought to play an active positive role in life and health in humans.[6]

The relative amounts of each element vary by individual, mainly due to differences in the proportion of fat, muscle and bone in their body. Persons with more fat will have a higher proportion of carbon and a lower proportion of most other elements (the proportion of hydrogen will be about the same). The numbers in the table are averages of different numbers reported by different references.

The adult human body averages ~53% water.[7] This varies substantially by age, sex, and adiposity. In a large sample of adults of all ages and both sexes, the figure for water fraction by weight was found to be 48 ±6% for females and 58 ±8% water for males.[8] Water is ~11% hydrogen by mass but ~67% hydrogen by atomic percent, and these numbers along with the complementary % numbers for oxygen in water, are the largest contributors to overall mass and atomic composition figures. Because of water content, the human body contains more oxygen by mass than any other element, but more hydrogen by atom-fraction than any element.

The elements listed below as "Essential in humans" are those listed by the US Food and Drug Administration as essential nutrients,[9] as well as six additional elements: oxygen, carbon, hydrogen, and nitrogen (the fundamental building blocks of life on Earth), sulfur (essential to all cells) and cobalt (a necessary component of vitamin B12). Elements listed as "Possibly" or "Probably" essential are those cited by the US National Research Council as beneficial to human health and possibly or probably essential.[10]

Atomic number Element Fraction of mass
[11][12][13][14][15]		 Mass (kg)[16] Atomic percent Essential in humans[17] Negative effects of excess Group
8 Oxygen 0.65 45 26 Yes (e.g. water, electron acceptor and DNA)[18] Reactive oxygen species 16
6 Carbon 0.18 13 9.5 Yes[18] (organic compounds) 14
1 Hydrogen 0.10 7 63 Yes[18] (e.g. water and DNA) Acidosis 1
7 Nitrogen 0.02–0.03 1.8 1.1 Yes[18] (e.g. DNA and amino acids) Nitrogen narcosis 15
20 Calcium 0.011–0.015 1.0 0.21 Yes[18][19][20] (e.g. Calmodulin and Hydroxylapatite in bones) Hypercalcaemia 2
15 Phosphorus 5–Script error: No such module "val". [21] 0.78 0.12 Yes[18][19][20] (e.g. DNA, Phospholipids and Phosphorylation) Hyperphosphatemia 15
19 Potassium 1.5–Script error: No such module "val".[22] 0.14 0.029 Yes[18][19] (e.g. Na+/K+-ATPase) Hyperkalemia 1
16 Sulfur Script error: No such module "val". 0.14 0.049 Yes[18] (e.g. Cysteine, Methionine, Biotin, Thiamine) Sulfhemoglobinemia 16
11 Sodium Script error: No such module "val". 0.10 0.041 Yes[19] (e.g. Na+/K+-ATPase) Hypernatremia 1
17 Chlorine Script error: No such module "val". 0.095 0.027 Yes[19][20] (e.g. Cl-transporting ATPase) Hyperchloremia 17
12 Magnesium Script error: No such module "val". 0.019 < 0.01 Yes[19][20] (e.g. binding to ATP and other nucleotides) Hypermagnesemia 2
26 Iron* Script error: No such module "val". 0.0042 < 0.01 Yes[19][20] (e.g. Hemoglobin, Cytochromes) Iron overload 8
9 Fluorine Script error: No such module "val". 0.0026 < 0.01 Yes (AUS, NZ),[23] No (US, EU),[24][25] Maybe (WHO)[26] Fluorine: Highly toxic

Fluoride: Toxic in high amounts

17
30 Zinc Script error: No such module "val". 0.0023 < 0.01 Yes[19][20] (e.g. Zinc finger proteins) Zinc toxicity 12
14 Silicon Script error: No such module "val". 0.0010 < 0.01 Probably[27] 14
31 Gallium Script error: No such module "val". 0.0007 < 0.01 No Gallium halide poisoning[28] 13
37 Rubidium Script error: No such module "val". 0.00068 < 0.01 No 1
38 Strontium Script error: No such module "val". 0.00032 < 0.001 No Calcium replacement 2
35 Bromine Script error: No such module "val". 0.00026 < 0.001 Maybe[29] Bromism 17
82 Lead Script error: No such module "val". 0.00012 < 0.001 No Lead poisoning 14
29 Copper Script error: No such module "val". 0.000072 < 0.001 Yes[19][20] (e.g. copper proteins) Copper toxicity 11
13 Aluminium Script error: No such module "val". 0.000060 < 0.001 No Aluminium poisoning 13
48 Cadmium Script error: No such module "val". 0.000050 < 0.001 No Cadmium poisoning 12
58 Cerium Script error: No such module "val". 0.000040 < 0.001 No
56 Barium Script error: No such module "val". 0.000022 < 0.001 No toxic in higher amounts 2
50 Tin Script error: No such module "val". 0.000020 < 0.001 Maybe[1] 14
53 Iodine Script error: No such module "val". 0.000020 < 0.001 Yes[19][20] (e.g. thyroxine, triiodothyronine) Iodine-induced hyperthyroidism 17
22 Titanium Script error: No such module "val". 0.000020 < 0.001 No 4
5 Boron Script error: No such module "val". 0.000018 < 0.001 Probably[10][30] 13
34 Selenium Script error: No such module "val". 0.000015 < 0.001 Yes[19][20] (e.g. selenocysteine) Selenium toxicity 16
28 Nickel Script error: No such module "val". 0.000015 < 0.0001 Maybe[1] Nickel Toxicity 10
24 Chromium Script error: No such module "val". 0.000014 < 0.0001 Maybe[1][19][20] 6
25 Manganese Script error: No such module "val". 0.000012 < 0.0001 Yes[19][20] (e.g. Mn-SOD) Manganism 7
33 Arsenic Script error: No such module "val". 0.000007 < 0.0001 Maybe[1][2] Arsenic poisoning 15
3 Lithium Script error: No such module "val". 0.000007 < 0.0001 Possibly (intercorrelated with the functions of several enzymes, hormones and vitamins) Lithium toxicity 1
80 Mercury Script error: No such module "val". 0.000006 < 0.0001 No Mercury poisoning 12
55 Caesium Script error: No such module "val". 0.000006 < 0.0001 No 1
42 Molybdenum Script error: No such module "val". 0.000005 < 0.0001 Yes[19][20] (e.g. the molybdenum oxotransferases, Xanthine oxidase and Sulfite oxidase) 6
32 Germanium Script error: No such module "val". < 0.0001 No 14
27 Cobalt Script error: No such module "val". 0.000003 < 0.0001 Yes (e.g. Cobalamin/Vitamin B12)[31][32] 9
44 Ruthenium Script error: No such module "val". 0.000007 < 0.0001 No [33] 8
51 Antimony Script error: No such module "val". 0.000002 < 0.0001 No toxic 15
47 Silver Script error: No such module "val". 0.000002 < 0.0001 No 11
41 Niobium Script error: No such module "val". 0.0000015 < 0.0001 No 5
40 Zirconium Script error: No such module "val". 0.000001 < 0.0001 No 4
57 Lanthanum Script error: No such module "val". Script error: No such module "val". < 0.0001 No
52 Tellurium Script error: No such module "val". Script error: No such module "val". < 0.0001 No 16
39 Yttrium Script error: No such module "val". < 0.0001 No 3
83 Bismuth Script error: No such module "val". < 0.0001 No 15
81 Thallium Script error: No such module "val". < 0.0001 No highly toxic 13
49 Indium Script error: No such module "val". < 0.0001 No 13
79 Gold Script error: No such module "val". Script error: No such module "val". < 0.0001 No uncoated nanoparticles possibly genotoxic[34][35][36] 11
21 Scandium Script error: No such module "val". < 0.0001 No 3
73 Tantalum Script error: No such module "val". < 0.0001 No 5
23 Vanadium Script error: No such module "val". 0.000020 < 0.0001 Possibly[10] (suggested osteo-metabolism (bone) growth factor) 5
90 Thorium Script error: No such module "val". < 0.0001 No toxic, radioactive
92 Uranium Script error: No such module "val". < 0.0001 No toxic, radioactive
62 Samarium Script error: No such module "val". < 0.0001 No
74 Tungsten Script error: No such module "val". < 0.0001 No 6
4 Beryllium Script error: No such module "val". < 0.0001 No toxic in higher amounts 2
88 Radium Script error: No such module "val". < 0.0001 No toxic, radioactive 2
2 Helium Script error: No such module "val". Script error: No such module "val". < 0.0001 No noble gas 18
10 Neon Script error: No such module "val". Script error: No such module "val". < 0.0001 No noble gas 18
18 Argon Script error: No such module "val". Script error: No such module "val". < 0.0001 No noble gas 18
36 Krypton Script error: No such module "val". Script error: No such module "val". < 0.0001 No noble gas 18

*Iron = ~3 g in males, ~2.3 g in females

Of the 94 naturally occurring chemical elements, 76 are listed in the table above. Of the remaining 18, it is not known how many occur in the human body.

Most of the elements needed for life are relatively common in the Earth's crust. Aluminium, the third most common element in the Earth's crust (after oxygen and silicon), serves no function in living cells, but is toxic in large amounts, depending on its physical and chemical forms and magnitude, duration, frequency of exposure, and how it was absorbed by the human body.[37] Transferrins can bind aluminium.[38]

Periodic table

Template:Periodic table (for higher organisms)

Composition

The composition of the human body can be classified as follows:

The estimated contents of a typical 20-micrometre human cell is as follows:[39]

Compound type Percent of mass Mol. weight (daltons) Compound Percent of molecules
Water 65 18 Script error: No such module "val". 98.73
Other inorganics 1.5 N/A Script error: No such module "val". 0.74
Lipids 12 N/A Script error: No such module "val". 0.475
Other organics 0.4 N/A Script error: No such module "val". 0.044
Protein 20 N/A Script error: No such module "val". 0.011
RNA 1.0 N/A Script error: No such module "val". Script error: No such module "val".
DNA 0.1 Script error: No such module "val". 46 Script error: No such module "val".

Tissues

The main cellular components of the human body[40][41][42]
File:Cells of the human body by mass.svg Cell type % mass % cell count
Erythrocytes (red blood cells) 4.2 85.0
Muscle cells 28.6 0.001
Adipocytes (fat cells) 18.6 0.2
Other cells 14.3 14.8
Extracellular components 34.3 -

Body composition can also be expressed in terms of various types of material, such as:

Composition by cell type

Script error: No such module "Labelled list hatnote". Script error: No such module "Labelled list hatnote". There are many species of bacteria and other microorganisms that live on or inside the healthy human body. In fact, there are roughly as many microbial as human cells in the human body by number.[40][43][44][45][46] (much less by mass or volume). Some of these symbionts are necessary for our health. Those that neither help nor harm humans are called commensal organisms.

See also

References

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  1. ↑ a b c d e Script error: No such module "Citation/CS1".
  2. ↑ a b Script error: No such module "citation/CS1".
  3. ↑ Script error: No such module "Citation/CS1".
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ Script error: No such module "citation/CS1".
  6. ↑ "Ultratrace minerals". Authors: Nielsen, Forrest H. USDA, ARS Source: Modern nutrition in health and disease / editors, Maurice E. Shils ... et al.. Baltimore : Williams & Wilkins, c. 1999, p. 283-303. Issue Date: 1999 URI: [1]
  7. ↑ Use WP:CALC for the mean of means for males and females, since the two groups are of about equal size
  8. ↑ See table 1. here
  9. ↑ Script error: No such module "citation/CS1".
  10. ↑ a b c Script error: No such module "citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Script error: No such module "citation/CS1".)
  14. ↑ Script error: No such module "Citation/CS1".
  15. ↑ Script error: No such module "Citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "Citation/CS1".
  18. ↑ a b c d e f g h Script error: No such module "citation/CS1".
  19. ↑ a b c d e f g h i j k l m n Script error: No such module "citation/CS1".
  20. ↑ a b c d e f g h i j k l Script error: No such module "citation/CS1".
  21. ↑ Script error: No such module "Citation/CS1".
  22. ↑ Script error: No such module "Citation/CS1".
  23. ↑ Australian National Health and Medical Research Council (NHMRC) and New Zealand Ministry of Health (MoH)
  24. ↑ "Fluoride in Drinking Water: A Review of Fluoridation and Regulation Issues"
  25. ↑ Script error: No such module "Citation/CS1".
  26. ↑ Script error: No such module "citation/CS1".
  27. ↑ Script error: No such module "Citation/CS1".
  28. ↑ Script error: No such module "Citation/CS1".
  29. ↑ Script error: No such module "Citation/CS1".
  30. ↑ Safe Upper Levels for Vitamins and Mineral (2003), boron p. 164-71, nickel p. 225-31, EVM, Food Standards Agency, UK Template:ISBN
  31. ↑ Script error: No such module "citation/CS1".
  32. ↑ Script error: No such module "citation/CS1".
  33. ↑ Script error: No such module "citation/CS1".
  34. ↑ Script error: No such module "Citation/CS1".
  35. ↑ Script error: No such module "Citation/CS1".
  36. ↑ Script error: No such module "Citation/CS1".
  37. ↑ Script error: No such module "Citation/CS1".
  38. ↑ Script error: No such module "Citation/CS1".
  39. ↑ Script error: No such module "citation/CS1".
  40. ↑ a b Script error: No such module "Citation/CS1".
  41. ↑ Script error: No such module "Citation/CS1".
  42. ↑ Script error: No such module "Citation/CS1".
  43. ↑ American Academy of Microbiology FAQ: Human Microbiome Template:Webarchive January 2014
  44. ↑ Judah L. Rosner for Microbe Magazine, February 2014. Ten Times More Microbial Cells than Body Cells in Humans?
  45. ↑ Script error: No such module "Citation/CS1".
  46. ↑ Script error: No such module "Citation/CS1".

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