The hair is composed of:

  • Keratin (a fibrous structural protein)
  • Natural oils or lipids
  • Water

These “ingredients” are arranged in 3 primary structures:

  • Thecuticle (outer layer)
  • Thecortex (inside the hair that consists of bundles of protein filaments)
  • Themarrow (spongy nucleus in the center of the cortex)