Atlas One · Human · Level 02

Atomic

Elements and ions — the periodic table in service of biology. Fifteen elements account for 99.9% of human body mass.

From oxygen as the terminal electron acceptor in mitochondria to iron at the core of hemoglobin, every elemental entry describes the physical form, the biological concentration, the key mechanisms, and the diseases that follow from deficiency or excess.

16Entries
99.9%Body mass in 15 elements
60+Elements detected in trace
Atlas One › Scales › Level 02 — Atomic

The human body is built from a small subset of the periodic table — six elements (H, C, N, O, P, S) make up all organic biomolecules; electrolytes (Na&sup+;, K&sup+;, Ca²&sup+;, Cl−, Mg²&sup+;) carry electrical signals and set osmolality; transition metals (Fe, Cu, Zn) sit in enzyme active sites and oxygen carriers; and trace elements (Se, I) are essential cofactors for thyroid and antioxidant enzymes. Deficiency of any essential element is a clinical disease. Each entry is modeled at physiological concentration, key biological roles, clinical syndromes, and connections to molecular and cellular scales above.

Level 02 — Atomic — 16 Entries

The biologically essential elements.

Entries cover atomic number, biological concentration, primary roles, and the disease states that arise from deficiency, excess, or displacement. Click any entry for the full record.

Hydrogen
H (Z=1)  ·  60% of body atoms  ·  Proton donor/acceptor; solvent backbone
H-bond donor; acid–base chemistry; bulk water; H&sup+; motive force
Carbon
C (Z=6)  ·  18% body mass  ·  sp²/sp³ hybridisation; backbone of all biomolecules
Backbone of proteins, lipids, nucleic acids; aromatic pi-stacking; carbonyl reactivity
Nitrogen
N (Z=7)  ·  3% body mass  ·  Protein/DNA constituent; urea cycle; NO synthesis
Amino group in amino acids; purine/pyrimidine bases; urea cycle; nitric oxide signaling
Oxygen
O (Z=8)  ·  65% body mass  ·  Mitochondrial terminal electron acceptor; ROS precursor
Complex IV terminal acceptor; superoxide/H&sub2;O&sub2; generation; carbonyl oxidation; hypoxia sensing (HIF-1α)
Sodium
Na&sup+;  ·  140 mM ECF  ·  Action potential; osmolality; SGLT2; Na&sup+;/K&sup+;-ATPase
Dominant extracellular cation; action potential depolarisation; serum osmolality; hypo/hypernatraemia
Potassium
K&sup+;  ·  140 mM ICF  ·  Resting membrane potential; cardiac AP repolarisation; ROMK/ENaC
Resting V&sub— determination; cardiac phase 3 repolarisation; hypokalaemia → TdP; hyperkalaemia → VF
Calcium
Ca²&sup+;  ·  1.2 kg total body  ·  Muscle contraction; synaptic release; coagulation; bone mineral
Troponin C activation; SNARE-exocytosis; coagulation cascade cofactor; hydroxyapatite lattice; PTH/calcitriol axis
Magnesium
Mg²&sup+;  ·  25 g total body  ·  Mg-ATP complex; NMDA block; TdP prevention; >300 enzyme cofactor
Kinase substrate stabilisation; NMDA receptor Mg²&sup+; block; Mg deficiency → TdP; >300 enzymatic reactions
Iron
Fe²&sup+;/Fe³&sup+;  ·  4 g total body  ·  Haemoglobin O&sub2; transport; ETC Fe-S clusters; hepcidin regulation
Heme-O&sub2; binding; Fe-S cluster electron shuttling; hepcidin-ferroportin axis; iron-deficiency anaemia; haemochromatosis
Phosphorus
PO&sub4;³−  ·  700 g total body  ·  Hydroxyapatite; ATP phosphoanhydride; kinase substrate; DNA backbone
Bone mineral matrix; ATP high-energy bond; phosphorylation signaling; DNA/RNA backbone; FGF23-klotho axis
Sulfur
S  ·  140 g total body  ·  Cysteine disulfide bridges; GSH antioxidant; CoA thioester; H&sub2;S gasotransmitter
Disulfide bond oxidative protein folding; glutathione Cys active site; CoA thioester energy transfer; H&sub2;S vasorelaxation
Chloride
Cl−  ·  100 mM ECF  ·  Electrochemical balance; CFTR; HCl gastric secretion; GABA hyperpolarisation
Major ECF anion; CFTR channel; parietal cell HCl secretion; GABA&sub— hyperpolarisation; hypochloraemic alkalosis
Copper
Cu²&sup+;  ·  100 mg total body  ·  Ceruloplasmin; cytochrome c oxidase Complex IV; SOD1; Wilson disease
Complex IV CuA/CuB centres; Cu/Zn-SOD1 (ALS); ceruloplasmin ferroxidase; Wilson disease (ATP7B); Menkes disease
Zinc
Zn²&sup+;  ·  2 g total body  ·  Zinc finger domains; insulin hexamer; >300 enzyme cofactor; immune function
Zinc finger transcription factor DNA binding; carbonic anhydrase; insulin storage hexamer; thymulin T-cell maturation
Selenium
Se  ·  15 mg total body  ·  Selenocysteine; GPx1/GPx4 ferroptosis gatekeeper; DIO1/2/3; Keshan disease
Sec21st amino acid; GPx4 guards against ferroptosis; DIO1/2 T4→T3 activation; Keshan dilated cardiomyopathy
Iodine
I−  ·  15 mg total body  ·  Thyroid hormone synthesis (T3/T4); NIS cotransporter; ¹³¹I therapy
NIS-mediated thyroid uptake; TPO-catalyzed iodination of thyroglobulin; T3/T4; hypothyroidism; ¹³¹I ablation in thyroid cancer

Help expand the Atomic Atlas

Trace element entries not yet filled include manganese (Mn — MnSOD, arginase), molybdenum (Mo — xanthine oxidase, sulfite oxidase), chromium (Cr — insulin sensitivity), fluoride (F — hydroxyapatite substitution), and vanadium. Each entry follows the same open schema with peer-reviewed citations.

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