Skeletal System
The 206 adult bones plus cartilage and ligaments that support the body, protect organs, anchor muscles, store calcium, and produce blood cells in red marrow.
Bone is living tissue, constantly remodeled by osteoblasts (build) and osteoclasts (break down) under hormonal control, which is how the skeleton doubles as the body’s calcium bank. Joints range from immovable skull sutures to freely movable ball-and-socket joints like the hip.