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Tour of the Human Body Systems

The Tour Starts Here!

The Immune System
The Nervous System
The Excretory System
The Respiratory System
The Circulatory Syatem
The Digestive System
The Skeletal System
The Muscular System
Glossary of Terms
Support Structure of the Human Hotel


Bone, like any living tissue is composed of cells in an extracellular matrix.

This matrix consists inorganic and organic components.


  • consists of proteoglycans, glycoproteins and collagen fibres.
  • collagen fibres provide tensile strength and flexibility.
  • this organic osteoid comprises 1/3 of bone weight.


  • consists mostly of crystals of calcium hydroxyapatite
  • derived from interaction of calcium phosphate  and calcium hydroxide 
  • a small amount of magnesium, fluoride and sulphate.

The hardness of bone is attributed to these minerals.  This combination produces a composite that is strong, flexible, resistant to shattering and ideally suited to carrying out its functions.