Final answer:
Bone renewal involves the activity of osteoclasts breaking down old bone as osteoblasts form new bone. This constant process of remodeling is essential for bone repair, structural integrity, and mineral balance.
Step-by-step explanation:
During bone renewal, as one osteon forms through the activity of osteoblasts, another is destroyed by osteoclasts. These cells are responsible for the resorption, or breakdown, of bone. The bone remodeling process also involves the combined activities of osteoclasts and osteoblasts, where osteoclasts resorb bone tissue and osteoblasts create new bone. This constant balancing act helps in the repairing of bones, maintaining mineral homeostasis, and allowing for structural changes based on stress and strains placed upon the skeleton.
The control of bone remodeling involves various hormones and enzymes that regulate the activities of these cells. For instance, parathyroid hormone (PTH) stimulates osteoclast resorption, while calcitonin inhibits it. Meanwhile, substances such as growth hormone and thyroid hormone encourage the formation of new bone by osteoblasts.