The phrase "the internal environment of the body" appeared thanks to the French physiologist Claude Bernard, who lived in the XIX century. In his works, he emphasized that the necessary condition for the life of an organism is the maintenance of constancy in the internal environment. This provision became the basis for the theory of homeostasis, which was formulated later (in 1929) by the scientist Walter Kennon.
Homeostasis - the relative dynamic constancy of the internal environment,
as well as some static physiological functions. The internal environment of the body is formed by two fluids - intracellular and extracellular. The fact is that each cell of a living organism performs a certain function, therefore, it needs a constant supply of nutrients and oxygen. She also feels the need for permanent removal of metabolic products. The necessary components can penetrate through the membrane exclusively in a dissolved state, which is why each cell is washed with tissue fluid, which has everything necessary for its vital functions. It belongs to the so-called extracellular fluid, and it accounts for 20 percent of body weight.
The internal environment of the body, consisting of extracellular fluid, contains:
- lymph (a component of tissue fluid) - 2 l;
- blood - 3 l;
- interstitial fluid - 10 l;
- transcellular fluid - about 1 liter (it includes cerebrospinal, pleural, synovial, intraocular fluids).
All of them have different composition and differ in their functional
properties. Moreover, the internal environment of
the human body may have a small difference between the consumption of substances and their intake. Because of this, their concentration is constantly fluctuating. For example, the amount of sugar in the blood of an adult can range from 0.8 to 1.2 g / l. In the event that the blood contains more or less certain components than necessary, this indicates the presence of a disease.
As already noted, the internal environment of the body as one of the components contains blood. It consists of plasma, water, proteins, fats, glucose, urea and mineral salts. Its main location is blood vessels (capillaries, veins, arteries). Blood is formed due to the absorption of proteins, carbohydrates, fats, water. Its main function is the interconnection of organs with the external environment, the delivery of necessary substances to the organs, the removal of decay products from the body. She also performs protective and humoral functions.
Tissue fluid consists of water and nutrients dissolved in it, CO
2 , O
2 , as well as dissimilation products. It is located in the gaps between tissue cells and is formed due to
blood plasma. Tissue fluid is an intermediate between blood and cells. It transfers from the blood to O
2 cells, mineral salts,
nutrients.Lymph consists of water and organic substances dissolved in it . It is located in the lymphatic system, which consists of lymphatic capillaries, vessels, merged into two ducts and flowing into the vena cava. It is formed due to tissue fluid in the sacs that are located at the ends of the lymphatic capillaries. The main function of lymph is to return tissue fluid to the bloodstream. In addition, it filters and disinfects tissue fluid.
As we see, the internal environment of the body is a combination of physiological, physico-chemical, respectively, and genetic conditions that affect the viability of a living creature.