Body complexity levels

Here is a breakdown of the levels of structural complexity within the body from lowest to highest:

• Atoms: The building blocks of life. An atom can be one of 92 different elements. The most common are Hydrogen, Oxygen, Nitrogen and Carbon, the mainstay of organic chemistry.
• Molecules: Made up of groups of atoms.
• Cells: The smallest units of independent living matter. Specialised to carry out particular functions.
• Tissues: Collections of cells with the same specialism.
• Organs: Collections of different tissues which work together to achieve certain outcomes.
• Systems: Groups of organs designed to work together to achieve a particular survival need.
• Human Body: Consists of several interdependent systems.