Human Body
What are bones made? If you ever have seen a skeleton of a fossil in a museum or truth, perhaps you think that all the bones are dead. And, although the bones in museums are dry, hard and are brittle, the bones in your body are very different. The bones that form your skeleton are alive and kicking, growing and constantly changing as other parts of your body. Almost all the bones in your body are composed of the same materials: the outer surface of the bone is called the periosteum. It is a dense and thin membrane that contains nerves and blood that nourish the bone.
The next layer is formed by compact bone. This part is smooth and very hard. It is the part you see when looking at a skeleton. There are many layers of spongy bone, which, as its name suggests, resembles a sponge inside compact bone. Spongy bone is not as hard as the compact, but is still very strong.
In many bones, the spongy part protects the innermost part of the bone, the bone marrow. The bone marrow is one kind of thick gelatin and its function is to produce blood cells. How to grow bones when you were a baby, you had very small hands, tiny feet, everything was extremely small in your body! Slowly, as ibas doing you more, everything was growing, including your bones. When he was born, a baby’s body contains approximately 300 bones. In the long run, they end up merging (join the grow) to become the skeleton’s 206 bones of an adult person. Some of the bones of the baby are entirely composed a special material called cartilage. Other bones of the newborn are partially composed of cartilage. The cartilage is soft and flexible. During childhood, as you’re going to grow, cartilage grows and, progressively, ends up becoming bone, with the help of calcium.