Bones are living organs with their own blood supply and nerves. Besides holding the body up, they make blood cells and store minerals.
Support and protection
The skeleton gives the body its shape and holds up soft tissues. The skull, ribs and pelvis shield the brain, heart, lungs and pelvic organs.
Movement
Muscles pull on bones through tendons, and the bones act as levers that turn at the joints. Most body movement works this way.
Making blood cells
Red marrow inside bones makes red cells, white cells and platelets. In adults, red marrow is found mainly in the flat bones, such as the pelvis, sternum and vertebrae, and in the ends of long bones.
Mineral and fat storage
Bone holds most of the body's calcium and phosphate and releases them when blood levels fall. Yellow marrow in the shafts of long bones stores fat.
At the bedside
Because bones have a rich blood supply, a femur fracture can lose about 1 liter of blood and a pelvic fracture even more, so check for shock. The same marrow lets fluids and drugs given by an intraosseous line reach the circulation fast.
Related guides
Written by Making Synapses. Topic reference: OpenStax, Anatomy and Physiology 2e (no text adapted).