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Medicine LibreTexts

1.10: Summary

  • Ions are charged particles, and electrolytes are solutions of ions in water.
  • Carbohydrates are made of carbon with hydrogen and oxygen (in the same ratio as water) linked together. The cell mainly uses carbohydrates for energy.
  • Fats are also made of carbon, hydrogen and oxygen. They are a powerful energy source, and are also used for insulation.
  • Proteins are the building materials of the body, and as enzymes make cell reactions happen. They contain nitrogen as well as carbon, hydrogen and oxygen.
  • Many also contain sulphur and phosphorous.


  • Ruth Lawson (Otago Polytechnic; Dunedin, New Zealand)