Bone provides support and protection to your body. It produces blood cells, and stores both minerals and triglycerides. We like to think of our bones as hard, static, solid, unmoving or unchanging pieces to our skeleton. But believe it or not, your living bone tissue is forever growing, remodeling and repairing itself (or in other words, breaking itself down and building itself back up). It is not stagnant or static at all, but is forever changing inside your body.

A single bone is composed of several different tissues working together. The bone tissue itself (also known as osseous tissue) is what we recognize most easily as the whitish-colored part of the bone. There’s also cartilage, dense connective tissue, epithelium, adipose and nervous tissues all working together to make each bone function as an individual, living organ.

Your bones form the structural framework of your body, known as the skeleton. They provide attachment points for your tendons and most skeletal muscles, and as such your bones assist with movement. When skeletal muscles that are attached to the skeleton contract, they pull on the bones like levers. This is how you move.

The skeleton also protects the majority of your organs from injury. Consider how your rib cage surrounds your heart, lungs, and other internal organs, or how your skull creates a hard barrier between your brain and the outside world.

Bone tissue stores a number of minerals, the majority of which are calcium and phosphorus. In fact, 99% of your body’s calcium is stored in your bones. Together these minerals contribute to the dense, strong nature of bone tissue. As other tissues or systems in your body require minerals like calcium to function, your bone releases the mineral into the blood for transport through to various parts of the body on demand.

Some bones in your body are filled with a connective tissue called red bone marrow. Red bone marrow is your internal cell and blood-producing factory. This is where your platelets and blood cells, both red and white are produced. When we are babies, almost all of our bones are filled with red bone marrow. As adults, much of our bone marrow changes from very actively producing red marrow to yellow marrow, which is inactive and consisting largely of fat cells.