Perera K. Sarath D2025-02-082025-02-082023-09https://dr.ichemc.ac.lk/handle/123456789/16137 - 40Research findings suggest that eleven elements are predominantly present in all biological systems. However, hydrogen, carbon, oxygen and nitrogen correspond to 99% of the total. Hydrogen constitutes 62.8% of the atoms in a human body. The percentage of oxygen, carbon and nitrogen are 25.4, 9.4 and 1.4%, respectively. Other essential elements make up the remaining 1% {sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P), sulphur (S) and chlorine (Cl)}. Very large percentages of hydrogen and oxygen arise from the high-water content present in living systems. Regarding our health and well-being, it is important to know about the elements found in biological systems, their functions and the level of toxicity.enElements in BiologyArticle