English scientist D. Wald wrote that "...the most complex machine of all, what ever created a man - well - "electronic brain" is nothing more than a child's toy in comparison with the simplest of living beings".
Man, as is known, is the most complicated of living beings. To understand the structure and functioning of any machine, you need to have the scheme of its construction. To understand how the human body and how it functions, you must first get acquainted with the General plan of its structure.
Between machine and a living organism and can lead known analogy: in both cases, the energy required for the operation and in both cases the aging parts need replacing. So, for example, a person in a state of complete rest, to ensure its activity, the act of breathing, heart rate, tone muscles , etc. is required 1,700 kcal per day during the work of the energy demand increases up to 3000 and even up to 7000 kcal (at large physical stress).
The work of the bodies is accompanied by continuous updates: some cells die, others will replace them. This process is made perfect without us, but in reality the size of such natural loss and tissue repair significant. For example, in an adult during the day dies and is replaced by approximately 1/20 part of the skin cells of the epithelium, 1/2 of all epithelial cells lining the mucous membrane of the digestive tract and is replaced by approximately 25 g of blood and so on
In animals and humans education, energy and the replacement of aging and dying tissues is due to metabolism. A large group of bodies shall exercise this fundamental process of life. These include, first, the organs of the digestive system, ensure that the intake of chemical substances from solid and liquid food; secondly, the respiratory system, delivering oxygen from air. In the tissues of the body some chemicals come into connection with oxygen ("burn") and serve for the formation of energy, others are used as "building blocks" for cells and other tissues. Of course, in the process of complex chemical transformations occurring in the digestive tract, the cells and tissues of different organs produce a lot of unnecessary body products, which often possess toxic action, you must delete them, and for this purpose there are special excretory organs (kidneys, sweat glands and other). Finally, living organisms are capable of reproduction without this life, of course, would cease, therefore, in addition to these there are the reproductive organs.
If to compare animals and plants, it is easy to see that in the latter case, there are also bodies of power, respiration, excretion, and reproduction. But this is limited to their "services". And this is understandable. Plants eat inorganic substances: carbon dioxide air, water and mineral salts in the soil. Of these inorganic substances they form, using solar energy, organic substances: proteins, fats, carbohydrates, which is built their body. They do not need to find food and live in one place. The situation is different in animals. Unlike plants, they may not in his body to produce organic matter from inorganic, they should get them from the bodies of other living beings. In this regard animals as a rule, spend their lives in search of food., Exploitation requires moving, so the animals in the process of the history of their development are formed bodies that are not in plants. That is why the digestive, respiratory, excretory system and reproductive organs are called authorities of plant, or vegetative, life, and machine movements, nervous system and sense organs, which are closely connected among themselves in the process of evolution, called the authorities animal or animal life. Strong bones and flexible articulation of them, covered by strong muscles and dressed leather, constitute the body, head and movable limbs healthy body. "The internal mechanism of the body is enclosed in its cavities. Write it in the familiar contours of the human torso (Fig. 5).
Fig. 5. General view the location of the viscera.
1 - the larynx;
2 - trachea;
3 - light;
4 - the heart;
5 - stomach;
6 - liver;
7 - the small intestine;
8-11 - large intestine;
12 - the bladder.
* Kilocalorie is the amount of energy needed for 1 kg of water heat up to 1 degree C. Energy, which is necessary to ensure the life of the body at rest, called the principal currency. It is important body functions.