Which cell type is primarily responsible for bone resorption?

Which cell type is primarily responsible for bone resorption?

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

Answer: (D)

Bone remodeling relies on two main players: cells that break down old bone and cells that build new bone. The cells that resorb bone are specialized multinucleated cells derived from the monocyte/macrophage lineage. They attach to the bone surface and create a sealed resorption area called a resorption lacuna, where they secrete acid to dissolve mineral and release enzymes like cathepsin K to digest the organic matrix. This resorbing activity is what clears old bone and makes way for new bone formation. In contrast, osteoblasts are the builders; they produce the bone matrix and promote mineralization to form new bone. Osteocytes are former osteoblasts embedded within the bone matrix that sense mechanical stress and help regulate remodeling. Chondrocytes produce cartilage, not bone, and thus aren’t the cells responsible for bone resorption. Therefore, the cell type primarily responsible for bone resorption is the osteoclast.

Bone remodeling relies on two main players: cells that break down old bone and cells that build new bone. The cells that resorb bone are specialized multinucleated cells derived from the monocyte/macrophage lineage. They attach to the bone surface and create a sealed resorption area called a resorption lacuna, where they secrete acid to dissolve mineral and release enzymes like cathepsin K to digest the organic matrix. This resorbing activity is what clears old bone and makes way for new bone formation.

In contrast, osteoblasts are the builders; they produce the bone matrix and promote mineralization to form new bone. Osteocytes are former osteoblasts embedded within the bone matrix that sense mechanical stress and help regulate remodeling. Chondrocytes produce cartilage, not bone, and thus aren’t the cells responsible for bone resorption.

Therefore, the cell type primarily responsible for bone resorption is the osteoclast.