The structure of the bone system

All the animals that has any complex structure, you need a solid Foundation of the body, to which was attached to the different organs.
In insects such basis is the outer covering of the body, consisting of very solid substances - chitin. The higher animals and man instead developed internal bone skeleton. He carries two functions. First, it is the basis, support for all other organs and tissues of the body; second, it protects the most important organs. So, the spinal cord and brain from all sides enclosed in a bony case. The heart and lungs protected ribs. The liver and kidneys, which we used to think of as the abdomen, located in the upper part and also covered ribs (liver - almost entirely).
It is clear that in order to perform these functions, craps has gained a lot of strength. For example, the large bone of the lower leg can withstand the top on its axis up to 1.5 tons! Like bone strength is provided by two factors: chemical composition and characteristics of the structure. Is bone, first, from salts of calcium and phosphorus (half the weight), giving bone hardness, second - from organic substances (a quarter of the weight), making bone elastic and resilient. The remaining quarter of the weight of the bones is, as already know, water. If soak bone-diluted acid, calcium salts dissolved, the bone will be flexible, as the vine. If ignited bone in the oven, will burn organic matter, the bone will lose its elasticity and will be shocks to burst. Over time, the bones become more calcium and less organic matter, so the elderly frequent bone fractures. In addition to the composition of bones, she, as already mentioned, has certain peculiarities of the structure. So, for the most part our bones are tubes, in the Central channel, which is bone marrow producing at an early age erythrocytes. Tubular shape of the bones is not accidental: tube stronger stem from the same amount of material.
The skeleton of a man is divided into the skeleton of the body, head and limbs. It consists of 86 pair (i.e., available from left and right) and 34 unpaired bones. The main parts of the skeleton known to everyone. We will stop so only a few details. So, not all know that from cheek in its upper part, called the cheek bone, to the bone hillock behind the ear bone thrown bridge - zygomatic arch. Outside it is covered by skin and ear, and beneath it lies the number of masticatory muscles. Only under these muscles begins wall skull - bone case that concludes our brain.
The main component of the skeletal system, like the skeleton of the skeleton, the spinal column consists of 24 separate the vertebrae, then rump (fused 5 vertebrae) and coccyx (accrete 4-5 vertebrae). Between the vertebrae are discs of cartilage, which makes the spine flexible. In the evening of each day cartilage several splashimages under the weight of the above parts of the body, and the growth of man is reduced by 1 to 1.5, see old age , the cartilage much compacted and sludinajums. For 80 years the person becomes 5, or even 7 cm lower than it was 40 years. These changes of the spine are all people. However, sometimes there are some abnormal phenomenon. So, schoolboy, sitting at the Desk, which is not suitable to its growth, can get a curvature of the spine; the habit of stooping, first correctable, can lead to a change in the structure of the spine. Therefore it is necessary to keep the correct posture of children and time to take action to fix it.