Bones and Muscles | Bones, bones, bones
Bones, bones, bones
An adult body has about 206 bones. The number varies from person to person because of differences in the number of small bones. Some bones are responsible for movement, including bones in the hands, feet, and limbs. Other bones primarily give protection to the internal structures, such as the skull protecting the brain and the ribs shielding the heart, lungs, and liver.
When looking at animal bones or at a skeleton, bones may appear to be static and dead, but in the body they are actually full of activity. Bones grow and change along with the person. They are made of living and nonliving materials: About 70 percent of an adult's bones are composed of minerals. The remaining part is bone tissueA group of similar cells in the bone with a common function., a group of similar cells with a common function. Bone tissue is constantly building new bone. In...
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