The Skeletal System
The skeletal system plays a major role in the body when it comes to protection, movement, and structure. There are four main purposes of bones: protection, movement, storage, and blood cell production. Some bones protect organs, support blood vessels, and support nerves. Other bones, like long bones, store minerals and fat for later use. Other bones support movements by letting muscles pull on them. They also give structure to your body and allow you to sit, stand, run, and perform other activities. The last main purpose of bones is to produce blood cells. Bones do this by using the marrow inside of them to make blood cells. Fully developed bones are extremely resilient against injuries but started out as a rubbery substance called cartilage. Eventually, that cartilage gets replaced by bone for more structural integrity. Some of these bones turn into either compact bone or spongy bone. Compact bone is rigid and easy to break at some extent. Spongy bone has several open spaces so it can support blood vessels and neurons. Spongy bones provide the most strength and support because they absorb shock easily. Cartilage in joints also absorbs shock easily. A joint is a place where two or more bones meet. At every joint there is always cartilage between the bones. Although bones are extremely tough, they can be broken, joints dislocated, and joints sprained. A broken bone is when a bone is fractured or completely broken. If that happens, the bone will be reset and put in a cast. A joint dislocation is when one or more bone are dislocated or moved out of place. Yet again, the bone will be reset but this time there will be no cast. A sprain is when a tendon or ligament is stretched too far or even torn. The skeletal system relates to the muscular system because muscles move bones. It also relates to the cardiovascular system because bones make blood cells. The skeletal system relates to the nervous system because bones support nerves and the spinal cord. The respiratory system relates to the skeletal system because ribs protect the lungs.
The picture to the right depicts a basic diagram of the human skeleton.