In the structure of the human body essential role game" ut cells, therefore, to begin to learn anatomy and physiology, the first thing to know about their structure and functions.
The concept of cells appeared in XVII century, when for the first time began to be used for the purpose of scientific observations of optical glass (lens). The Dutchman A. Leeuwenhoek, who was involved in the grinding of glass, for the love of this fine art for the first time began to see the smallest living creatures in a drop of water. He created the first microscope and laid the Foundation for scientific microscopy. To the exciting new field of research has addressed numerous scientists. As a result of their work to the 30-th of the XIX century has collected a vast material for the study of the microscopic structure of living nature on the basis of which were made extremely important conclusions. Installed it, on the one hand, there are the simplest organisms represented by only one cell, on the other hand, it was found that plants and animals with a complex structure of a body, composed of an enormous number of cells. It turned out that all cells, whatever body they belong to, have the same laws of the structure. Here was made important conclusion that all living beings on our planet, and plants and animals have a common origin, a common sources of development in the process of evolution.
and - animal cell; b - a plant cell. 1 - shell; 2 - protoplasm; 3 - a kernel.
The structure of the cells can be schematically presented as follows (Fig. 1). Its main parts are protoplasm, the kernel and the shell. The main part of the cell is protoplasm. In appearance it is a viscous, colourless transparent liquid. Chemical composition it is very complicated: it includes organic matter - proteins, fats, carbohydrates, vitamins and inorganic substances - water, mineral salts. By volume of water is 95-98% (!) the whole mass of cells; the water with the dissolved salts is an environment in which proceed all processes of vital activity of cells. From organic substances essential proteins. It is the protein molecules provide effective features of their structure and chemical properties of the main vital process - metabolism. Fats and carbohydrates are mainly energy material: due to their oxidation ("burning") formed by the energy needed for life. The structure of protoplasm is very complex. Considering the cell under the microscope, you can find that in the cytoplasm of some of education, the so-called organelles (Fig. 2), which is similar bodies complex organism regulate vital processes.
Fig. 2. The scheme of the structure of cells according to electron microscopy.
The most important regulatory apparatus of the cell is the nucleus, without which it cannot function fully: loses the ability to grow and reproduce. Of particular importance are located in the nucleus of special education - chromosome. Scientists have long been linked with them the most important ability of living organisms to bequeath to posterity their main properties. However, only in recent years managed to find out their chemical structure and principal mechanism of heredity. The studies of the biochemistry and genetics (scientists involved in research on heredity) proved that the chromosomes are composed of particles called genes *. Each gene is a cipher certain properties of the organism.
* The word gene is derived from the Greek - "genos" -- birth, race.