What are our bones and skin made out of?

My brother is curious and I found this web so i thought i could find it out for him.What are our bones and skin made out of?
Bones are made of a mix of hard stuff that gives them strength and tons of living cells which help them grow and repair themselves. Like other cells in your body, the bone cells rely on blood to keep them alive. Blood brings them food and oxygen and takes away waste.


If bones weren't made of living cells, things like broken toes or arms would never mend. But don't worry, they do. That's because your bone cells are busy growing and multiplying to repair the break! How? When you break your toe, blood clots form to close up the space between the broken segments. Then your body mobilizes bone cells to deposit more of the hard stuff to bridge the break.


Skin is alive. It's made of many thin sheets of layers of flat, stacked cells in which you'll find nerves, blood vessels, hair follicles, glands, and sensory receptors.


Older cells are constantly being pushed to the surface by new cells which grow from below. When the old ones reach the top, they become wider and flatter as they get rubbed and worn by all your activity. And, sooner or later, they end up popping off like tiles blown from a roof in a strong wind. In fact, every minute 30,000-40,000 dead skin cells fall from your body! In approximately a month's time, your body has made a whole new layer of skin cells!


As an adult, you may have more than 20 square feet of skin -- about the size of a blanket.


You are likely to shed some 40 pounds of skin in a lifetime.


Right now there are over a million dust mites, microscopic critters invisible to the naked eye, on your mattress and pillow, chomping on the dead skin cells that fell off you last night!What are our bones and skin made out of?
mostly water