What makes up a bone, Joints, Types of bones,

Bones- It has been believed that are bones are dry, although it has been proved that are bones are one-third water. The bones contain living and nonliving parts. Minerals make our bones strong and sturdy, but they are not living. Our bones are covered almost everywhere by a thin white membrane which is filled with cells that help the growth and repair of bones. Beneath the membrane is the hardest part of the bone, it is called the compact part of the bone. The bone is so hard that doctors have to use a special kind of saw just to cut through the layer. In this layer there are tiny holes that little nerves and blood vessels pass through the bone. In the very center of your bone there is a type of sponge substance called bone marrow. The bone marrow produces many red blood cells, the red blood cells carry oxygen throughout your bloodstream. Now the other blood cells are white they can fight off infections. In your body there are blood platelets, they help our body stop bleeding when we have a cut. The bony substance itself is formed in long cylinder forms nested one in another. Bone cells, like all other cells need oxygen and food supply which is carried to them throught the bloodstream.