Question

If the activity of osteoclasts exceeds that of osteoblasts a bone, how will the mass of the bone be affected?

Answer 1

Osteoclasts are responsible for the resorption of bone, while osteoblasts are responsible for the formation of bone from mesenchymal cells. In the phase of bone remodelling, these two types of cells rely on each other for development and are related.

Complete answer:
Osteoclast: By secreting acid and collagenase, a process known as bone resorption, the osteoclast disassembles and digests hydrated protein and mineral composites at a molecular level. This process also helps to control the level of calcium in the blood.
Osteoblasts are specialised mesenchymal cells that synthesise the matrix of bones and coordinate the skeleton's mineralization. These cells work in harmony with bone-resorbing osteoclasts in a continuous cycle that takes place throughout life. If the activity of bone demineralizing osteoblast activity exceeded the production of new bone osteoblast activity, the mineral content of the bone and thus its mass would decrease, making it weaker. This leads to low bone density and the risk of developing osteoporosis when bone mass loss continues for a long time.

Reason for the increase in the activity of osteoclasts: Parathyroid hormone (PTH) and calcitonin are two hormones that impact osteoclasts. PTH stimulates proliferation and activity of the osteoclast. As a consequence, calcium is released into the circulation from the bones, thus increasing the concentration of calcium ions in the blood.

Note: Osteoporosis is a bone disease that occurs when too much bone is lost from the body, too little bone is produced or both. As a result, the bones become weak and may break from a fall, or from sneezing or minor bumps in severe cases.