Question: what are bones made of?

Melissa Ladyman answered on 16 Jun 2016:

Bones are made of different types of cell, which all have different jobs. Bones are not the same all of the way through- they have a hard, smooth surface but the inside of bones is filled with bone marrow. This is where blood cells are made. In the ends of long bones, and in the bones in your spine there is another type of bone called ‘spongy’ bone, which looks a bit like a sponge with lots of holes. The spongy bone is lighter than the hard bone surface, which is good otherwise our skeletons would be too heavy for us to move. Bones also need blood vessels to give the cells oxygen and vitamins to keep them healthy.

One of the main parts of bone is a type of chemical compound called calcium phosphate- which is why calcium is so important to help your bones grow!