Bones are important because they provide a frame for the body, protect organs, anchor muscles and store calcium. Humans have 206 lightweight and strong bones that support the body’s total weight.
The skull encases the brain and creates the shape of a person’s face. The backbone protects the spinal cord, which is the route for messages transmitted between the brain and the body. The cage is composed of ribs, and it protects vital organs, such as the heart, lungs, liver and spleen. The pelvis is responsible for safeguarding the bladder and intestines. In women, the pelvis also shelters the reproductive organs.
Bones start to develop while an individual is still in the mother’s womb. The skeleton is composed of flexible cartilage as it forms. It undergoes the process of ossification in the following weeks, wherein hard deposits of calcium phosphate and stretchy collagen, which are the main parts of bones, replace the cartilage. Ossification takes up to 20 years to complete.
Children and young teenagers have smaller bones than adults. Their bones consist of growth plates, which contain divisions of cartilage cells that multiply, grow longer and turn into sturdy, mineralized bone. The growth plates of girls typically develop into hard bone earlier than boys. Bones continuously change as the body creates new bone and breaks down old bone. A person’s bone mass constantly increases until the age of 30.