The human skeleton

The human skeleton is made up of more than 200 bones of different shapes and sizes.

Bones are made of:

• a type of protein called collagen
• minerals such as calcium and phosphate.
• The combination of collagen and minerals makes the bones strong.

Bones have many important roles in the body, including the following:

• Supporting our bodies – the joints at the end of bones act as levers, allowing us to move around. The joints are covered in cartilage which allows the joints to move smoothly.
• Protecting parts of our bodies from injury – for example, the ribs protect the heart and lungs, and the skull protects the brain.
• Storing important minerals, such as calcium, for our bodies to use.

Making blood cells – some bones are filled with a soft, spongy material called bone marrow. The bone marrow is where the blood cells are made.

Bones contain 2 types of cells that break down old bone and replace it with new bone:

• Osteoclasts break down and remove old bone.
• Osteoblasts make new bone.
• This helps bones to keep their strength and shape.