Re: What are the functions of the skeleton?

Dear Caroline,

The skeleton has several main functions, some pretty obvious and some less 
so. First and most obvious is support. Bones are pretty strong, and they 
hold you up. If you didn't have bones, you'd fall down like a bag full of 
Jello! Second, bones create protected spaces in your body. Your heart and 
lungs, for example, and other sensitive organs, are protected by you rib 
cage. The soft bone marrow where your blood cells are constantly being made 
is kept safely inside your bones. Even more importantly, your brain and 
spinal cord, which are very soft and easily damaged, are protected by the 
very strong skull and vertebrae (backbones). Third, movement. Without bones 
to pull against, your muscles would have a tough time getting your arms, 
legs or fingers to move - or your jaw to move and chew food when you eat! 
Fourth, a few bones have very specialized functions. In your ear, sound 
vibrations that make your eardrum vibrate are picked up and transmitted 
through the tiny bones known as the hammer, anvil, and stirrup, which in 
turn send them into the cochlea, where they get changed into nerve impulses 
that your brain can sense. 

Finally, and here's the least obvious one, bones act like a "bank" where 
your body stores minerals that it needs to carry out its special chemistry. 
Unseen except in the microscope, your bones have cells in them that make 
bone (called "osteoblasts") and cells that eat bone (called "osteoclasts"). 
All through your life, there are "deposits" and "withdrawals" made by these 
cells. The hard, white mineral stuff in bones is made mainly of the 
elements calcium and phosphorus. Both of these are absolutely necessary to 
your normal body chemistry for everything from transmitting nerve signals 
to your muscles, to building new DNA, to generating the energy you use. So 
your body builds bone when you have enough of these things in your diet, 
and at the same time, it digests bone to keep the calcium and phosphorus 
levels in your bloodstream at level they need to be at for all these 
biochemical processes to work. When you're grown up, about 10% of your 
skeleton will get torn down and rebuilt every year in this constant 
remodeling process.

Hope this answers your question.

Paul Odgren, Ph.D.
Dept. of Cell Biology
University of Massachusetts Medical School
Worcester, USA