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What Are Bones For?
frame, protection, bone marrow, osteocyte
Musculoskeletal System Unit
Can you tap your foot, bounce a ball, pat your head and stomp your other foot all at once? Now, how about adding 202 more moves to that? Well, did you know that you probably do this every day? That is how many bones you carry around in your body. If you dance or play a sport, you may be moving all the 206 bones in your body at the same time!
Now that we have the frame up why don't we put a roof on this.
Some bugs have their skeletons, or all their bones, on the outside of their bodies, but our skeletons are safely hidden inside of us. If you were to build a dog house, you might first use boards to build a square box, called a frame. A frame is what holds something up and gives it shape. Then you might cover the square frame with flat pieces of wood to keep rain off of your dog. Your skeleton is like the square box, giving your body its shape.
If you were to rip open your arm to look at your bones, the first thing you would see is a thin, skin-like covering which is the part that feels pain when you break your bone. The smooth, white layer under that is hard and very strong. This part keeps your bones from breaking. In the middle of the bone, you would see something that looks like a sponge but is tough like a chain link fence.
We may want to thank our bones for holding our bodies up, but that is not all that they do. They are like busy bus stations where some of the most important jobs in our body are taking place. In the middle of some of your bones there is this red stuff that looks like jam called bone marrow. Bone marrow makes red blood cells and other cells that protect your body from sickness. Blood is very important because it carries the things we need to every cell in our body, and it carries the things they don't need away from them.
Our skull and ribs protect many of our organs.
Many of your bones also do you a huge favor by keeping your insides safe. Your bones give your body protection, which means they keep them safe. Picture a scary movie with monsters that have their brains and their hearts on the outside of their bodies. Even though that would be kind of creepy, it would make it a lot easier to get rid of them. Thankfully, our brain is covered by our skull, kind of like a helmet. What about your ribs, what do you think they protect?
Not only is my skin soft but my bones are kind of soft too.
When you were a baby growing inside your mother, your bones started out soft and could bend like your ears. It is only after you were born and as you began to grow that they started to get hard and strong. People cannot walk as soon as they are born, but many baby animals can because their bones are already hard when they are born. Most of our bones are made of cells called osteocytes that fix up our bones to keep them healthy and strong. Have you ever seen someone fixing up an old building, taking out old floors and walls and putting new ones in? Well, in millions of spots all over your skeleton, you have groups of cells digging holes in your bones, getting rid of the old, worn out parts. This may not sound like a good thing, but it is a great thing because then new cells can move in and start making fresh, new bone!
Your bones are very strong and hold all of your weight. Your biggest bone which is found in your thigh can lift or hold something 30 times more than what it weighs. Can you lift 30 times your weight? Your smallest bone is in your ear, and without it, you would not be able to hear very well. Did you know that more than half of your bones are in your hands and feet and because of them you can pick things up, write, walk and run?
Just like your dog's house, your frame is very important. The bones that make up your frame give you shape and keep you from being a blob of Jello lying on the floor. So, do not forget to take good care of all 206 bones by eating healthy foods and playing outside. If you do, your frame will protect you just like your dog's house protects him.