How do bones grow?

Bones are made of a network of calcium laid down by cells. As children grow, special cells at the end of bones add new calcium to the network of bone. Children have layers of these cells in the shape of plates at the ends of their bones. These are called “growth plates,” and they close up when kids reach their full adult height. To grow in a healthy way, bones need protein, calcium, and other minerals. In addition, bones need the hormones that increase at puberty, including estrogen and testosterone. Bones also need vitamin D, to help absorb calcium, and regular exercise to keep bones strong.