Our skeleton is like a skyscraper
Imagine a giant skyscraper reaching up into the sky. Up at the very top there are hundreds of workers, busy doing their jobs. No matter what the weather is like outside, these workers feel safe, because they know that the building was built very strong. Even on windy days, the building will not fall over.

What gives buildings their super strength? The secret is in their bones. Well, sort of. Buildings are built around a steel framework. This framework holds the weight and allows the builders to go as high as they want.

Your body is similar to a skyscraper. A small ant might look up at you and say “wow, what keeps that large animal from falling over”. The secret to your strength lies in your bones.

The framework of a building provides it with strength

Just like a skyscraper, your body is built around a hard and strong framework. Instead of steel and concrete, your bones are made out of very hard materials that we will explore later.

In a building, workers use nails, bolts, glue and concrete to hold the building to the framework. Your body has similar materials, such as ligaments and muscles, which hold everything together.

Your body is made up of four main types of bones. Long bones, such as the bones in your arms and legs, short bones such as the bones in your hands, feet, and spine, flat bones, which protect your organs, and provide a place for muscles to attach, and irregular bones, which are simply all the bones that are not long, short, or flat.

A newborn baby has around 350 bones in their body. As they grow older, many of these bones fuse together. When two bones fuse together, they grow together, becoming one larger bone. And adult has approximately 206 bones.

Bone
Nearly half of the bones in your body are found in your hands and in your feet. Think about that. You hands are so complex, and flexible that they along with your feet contain half the bones in your entire body. This makes the human hand the most advanced and amazing appendage on any animal on Earth.

In order to provide your body with the strength you need to keep your shape, to move, to hold your weight, and to protect your organs, your bones need to be very strong. However, in order to allow you to move easily, to run and jump, and to be active, your bones also need to be as light as possible, and as small as possible.

Very large fat bones would certainly serve the purpose of protecting your body, and providing strength. However, if they were too large, movement would be awkward. Very small thin bones would allow you to move, jump, and play, but are much more likely to break.

Femur
The solution is an amazing biological mix of medium sized, very strong, yet light weight bones. What makes your bones so light, yet also very strong? The secret is in the chemicals. Your bones are made out of several very hard yet lightweight chemicals. In order to keep your bones healthy, you need to make sure your body gets plenty of these chemicals. The most important of these is calcium. One very important source of calcium is milk. Thus, drinking milk makes your bones stronger.

Blood

Your bones have one more very important function. In addition to providing strength and protecting your body, your bones also are where blood is created. Your blood is alive. It is made up of millions and millions of tiny blood cells. These cells only live for a few months. This means that your blood supply must constantly be regenerated.

If you could see into the very center of your bones you would find a soft spongy material called bone marrow. This marrow is where new baby blood cells are being created. Whenever you bleed, or your blood cells die of old age, they are replaced by new blood cells that come from inside your bones.