Which bone cell is responsible for bone resorption?

• A. Osteoblast
• B. Osteoclast
• C. Osteocyte
• D. Chondrocyte

Answer: (B)

In bone remodeling, the cell responsible for breaking down bone tissue is the osteoclast. These are large, multinucleated cells that attach to the bone surface and release acids and proteolytic enzymes to dissolve mineral and organic matrix, effectively resorbing old bone so new bone can form. This resorption is then followed by activity from osteoblasts, which lay down new osteoid and promote mineralization to rebuild the bone.

Osteoblasts and osteocytes play different roles. Osteoblasts build bone by secreting osteoid that becomes mineralized; osteocytes are former osteoblasts embedded inside the bone matrix and act as mechanosensors and regulators of remodeling signals. Chondrocytes, on the other hand, are cartilage cells involved in cartilage formation, not in resorbing bone tissue in mature bone. Therefore, the cell that resorbs bone is the osteoclast.