The phrase "internal environment of the body" appeared thanks to the French physiologist Claude Bernard, who lived in the 19th century. In his works, he emphasized that a necessary condition for the life of an organism is to maintain constancy in the internal environment. This provision became the basis for the theory of homeostasis, which was formulated later (in 1929) by the scientist W alter Cannon.
Homeostasis is 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 specific function, so it needs a constant supply of nutrients and oxygen. She also feels the need for the constant removal of metabolic products. The necessary components can penetrate the membrane only in dissolvedstate, which is why each cell is washed by tissue fluid, which contains everything necessary for its vital activity. It belongs to the so-called extracellular fluid and accounts for 20 percent of body weight.
The internal environment of the body, consisting of extracellular fluid, contains:
- lymph (an integral part of tissue fluid) - 2 l;
- blood - 3 l;
- interstitial fluid - 10 l;
- transcellular fluid - about 1 liter (it includes spinal, pleural, synovial, intraocular fluid).
They all have a different composition and differ in their functional
properties. Moreover, the internal environment of the human body can have a small difference between the consumption of substances and their intake. Because of this, their concentration fluctuates constantly. 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 of certain components than necessary, this indicates the presence of the disease.
As already noted, the internal environment of the body contains blood as one of the components. It consists of plasma, water, proteins, fats, glucose, urea and mineral s alts. Its main location is the blood vessels (capillaries, veins, arteries). Blood is formed due to the absorption of proteins, carbohydrates, fats, water. Its main function is the relationship of organs with the external environment, delivery toorgans of essential substances, excretion of decay products from the body. It also performs protective and humoral functions.
Tissue fluid consists of water and nutrients dissolved in it, CO2, O2, as well as dissimilation products. It is located in the spaces between tissue cells and is formed by blood plasma. Tissue fluid is intermediate between blood and cells. It transports from blood to cells O2, mineral s alts, 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 sacs that are located at the ends of the lymphatic capillaries. The main function of the lymph is to return tissue fluid to the bloodstream. In addition, it filters and disinfects tissue fluid.
As we can 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 being.
