Bone

skeleton · human body · strong stuff

Bones are alive. Your bones might seem dead and hard, but they're actually living tissue that grows, heals, and changes throughout your life. They're constantly being rebuilt and refreshed, kind of like how your body replaces old skin.

Blood cell factory. Deep inside your bones is a spongy material called bone marrow that works like a factory, making both red blood cells that carry oxygen and white blood cells that fight germs.

Body's armor. Your bones form a protective cage around your delicate organs like your heart, lungs, and brain, keeping them safe from bumps and injuries.

Mineral storage. Bones are like a mineral bank that stores calcium and other important minerals your body needs. When you don't eat enough calcium, your body can withdraw some from your bones.

Hearing helpers. Three tiny bones in your ear, called the hammer, anvil, and stirrup, vibrate when sound waves enter and help you hear everything from whispers to music.