Article by Beppe Cart
Right in the center of the body is a truly ingenious and very resistant structure, but at the same time so light that it allows us to move freely. The skeleton is made up of 206 rigid bones ... It is a structure that keeps the body upright and forms a protective cage for the delicate internal organs.
Figure: main bones of the human skull
The most vulnerable organ in the body requires a lot of attention. The brain is protected by 22 bones fused together to form a sort of natural "helmet", which protects it from shocks. But the strongest bones are those that bear the heaviest loads. . When the body lands after a jump, the femurs are impacted by half a ton, a force that would shatter even granite. Yet the femur is constructed to withstand this force. The ends of the bone have a structure. honeycomb that consists of props and arches, structures that unload the forces on the median section which is stronger and more compact. It is this honeycomb structure that makes the bone resistant and at the same time light.
Figure: the epiphyses (ends) of the long bones (such as the femur shown in the figure) are formed by a so-called spongy (or trabecular) honeycomb bone (in the figure indicated as cancellous). This structure makes the bone more light and flexible (therefore easier to move), and suitable for hosting bone marrow, blood vessels and nerves inside. The bone trabeculae are a system of finely intertwined arches and vaults, which delimit these channels and increase the strength of the bone spongy; it is no coincidence that their arrangement in the skeleton follows the load lines to which it is usually subjected.
A second type of bone tissue, called compact (in the figure indicated as compact), has instead the task of supporting the body weight, protecting the organism and acting as a deposit of minerals. This tissue forms the outer covering of the bones and is also concentrated in the body (diaphysis) of the long bones.
This example of nature's perfection inspired an engineer working in Paris in the late 1800s. He wanted to design the tallest structure in the world and the strongest material then available was iron. However, if he used too much of it, the structure would collapse underneath. His own weight. Inspired by the shape of the femur, the engineer used the iron only where it would have strengthened the structure.
The name of this engineer is GUSTAVE EIFFEL, and his tower has become the symbol of Paris. Just like the props and arches of a femur, the metal bars also discharge all the forces that act on the Eiffel Tower on the strongest parts of the tower itself, that is, the support bases.
But unlike the Eiffel Tower, the bones are not stuck in the earth, they are constantly in motion and must undergo all kinds of tension and traction. Any force exerted on the bone triggers a surprising reaction! In response to a mechanical stimulus, a veritable army of microscopic machines in charge of building the bone comes into action. When a force is exerted these cells produce a liquid layer of bone material, then the layer hardens to reinforce the structure. On the contrary there are areas that do not need to be strengthened and in this case some cells responsible for degrading the bone use hydrochloric acid to dissolve the superfluous material. Just like a team of sculptors, the bone cells continually reshape the skeleton. to make it strong where it is needed and light where it can afford to be.
But it's not just the bones of athletes that undergo a continuous change, this process takes place in the bones of all of us ... On average every year we take about five million steps, each of which helps to reshape our bones. Every action is followed by a reaction !! Exercising strengthens the skeleton, while driving a car weakens it. Human beings therefore continue to reshape their skeleton for life !!! Bone cells work so intensely that every ten years every person finds himself one. skeleton completely restored So whatever your age, your skeleton cannot be more than ten years old.
