Which process involves the breaking down of bone tissue?

• A. Ossification
• B. Calcification
• C. Osteolysis
• D. Remodeling

Answer: (C)

The question tests understanding of bone turnover, specifically the step where bone is broken down. Osteolysis is the process of breaking down bone tissue. In this phase, osteoclasts attach to the bone surface and release acids and enzymes that dissolve the mineral and organic matrix, releasing calcium and other minerals into the bloodstream. This resorption is a deliberate part of remodeling, allowing damaged or old bone to be replaced with new bone formed by osteoblasts.

Ossification, by contrast, is bone formation, either replacing cartilage (endochondral) or forming directly from connective tissue (intramembranous). Calcification means deposition of calcium salts in tissues, which can occur in various contexts and isn’t the specific breakdown of bone. Remodeling is the broader cycle that alternates resorption and formation over time, with osteolysis representing the resorption phase within that cycle.