Answer:
Bones are composed of mainly collagen fibre and osteoclast are the cells used to breakdown bone tissue and osteoblast cells replace it.
Step-by-step explanation:
Bone is made up of tough matrix which contains mainly collagen fibres which provide bone it's flexibility and strength. The deposition of calcium over collagen makes bones more strong. Blood vessels and fat deposits are also parts of a bone.
Osteoclasts are the cells which are specialized for degenerating old bone tissue and osteoblast are the cells which make new bone tissue and replace it from old bone tissue. This process is called bone remodeling.