Many people believed that the bone is static and inert, but this idea is
incorrect, the organic and mineral components of the bone matrix are continually
being recycled and renewed through a process called remodeling. This process
goes under way throughout life, as part of normal bone maintenance. Bone
remodeling plays a key factor between the activities of osteocytes, osteoblasts,
and osteoclasts. In the adult stage, osteocytes are continually removing and
replacing the surrounding calcium salts. But osteoclasts and osteoblasts also
remain active, even after the epiphyseal plates have closed. For the most part
their activities have a balance. As one osteon forms through the activity of
osteoblasts, another is destroyed by osteoclasts. In young adult, approximately
each year one fifth of the adult skeleton is demolished and the rebuilt or
replaced. The turnover and recycling of minerals give each bone the ability to
adapt to new stresses. The mechanism that controls the internal organization and
structure is osteoblast. Whenever a bone is stressed, the mineral crystals
generate electrical fields. Osteoblasts have an attraction to these electrical
fields, and once they are in this area they begin to produce bone. Since bones
are adaptable , their shapes reflect the forces applied to them. Heavily
streeled bones become thicker and stronget, whereas bones not being accessible
to ordinary stresses will be deteriorated. Therefore is important to exercise
daily to maintain a normal bone structure.