The internal environment of the human body
The organism of any animal is extremely complex. This is necessary to support homeostasis, that is, consistency. Some conditionally permanently, while others, more developed, there is an actual constancy. This means that no matter how the environmental conditions change, the body maintains a stable state of the internal environment. Despite the fact that organisms have not yet fully adapted to the living conditions on the planet, the internal environment of the body plays an important role in their life activity.
The concept of the internal environment
The internal environment is called a complex of structurally separated body parts, under no circumstances other than mechanical damage that are not in contact with the outside world. In humans, the internal environment is represented by blood, interstitial and synovial fluid, liquor and lymph. These 5 types of fluids in the complex are the internal environment of the body. As such, they are called for three reasons:
- first, they do not come into contact with the external environment;
- secondly, these fluids maintain homeostasis;
- thirdly, the environment is a mediator between the cells and the outer parts of the body, protecting it from external adverse factors.
The value of the internal environment for the body
The internal environment of the body consists of 5 types of liquids, the main task of which is to maintain a constant level of nutrient concentrations near the cells, to maintain the same acidity and temperature. Due to these factors, it is possible to ensure the functioning of cells, of which there is nothing more important in the body, since they constitute tissues and organs. Therefore, the internal environment of the body is the widest transport system and the area of extracellular reactions.
It moves nutrients and transports metabolic products to the place of destruction or elimination. Also, the internal environment of the body carries hormones and mediators, allowing some cells to regulate the work of others. This is the basis of humoral mechanisms that ensure the flow of biochemical processes, the total result of which is homeostasis.
It turns out that the entire internal environment of the body (GUS) is a place where all nutrients and biologically active substances must go. This is a part of the body that should not accumulate metabolic products. And in the basic sense, VSO is the so-called road, along which “couriers” (tissue and synovial fluid, blood, lymph and cerebrospinal fluid) deliver “food” and “building material” and divert harmful metabolic products.
Early organisms internal environment
All representatives of the animal kingdom developed from single-celled organisms. They have the only components of the internal environment of the body was the cytoplasm. From the external environment, it was limited to the cell wall and cytoplasmic membrane. Then the further development of animals proceeded according to the principle of multicellularity. In intestinal cavities, there was a cavity separating cells and the external environment. It was filled with a hydrolith that transported nutrients and products of cellular metabolism. This type of internal environment was present in flatworms and intestinal cavities.
The development of the internal environment
In animals of classes of roundworms, arthropods, mollusks (except cephalopods) and insects, other structures constitute the internal environment of the organism.These are the vessels and areas of the open channel through which the hemolymph flows. Its main feature is the acquisition of the ability to transport oxygen through hemoglobin or hemocyanin. In general, such an internal environment is far from perfect, because it developed further.
Perfect indoor environment
A perfect internal environment is a closed system, which excludes the possibility of fluid circulation through isolated areas of the body. In this way, the bodies of representatives of the classes of vertebrates, ringed worms, and cephalopod mollusks are arranged. Moreover, it is the most perfect in mammals and birds, which also have a 4-chamber heart to support homeostasis, which provided them with a warm-bloodedness.
The components of the internal environment of the body are as follows: blood, lymph, joint and tissue fluid, cerebrospinal fluid. It has its own walls: endothelium of arteries, veins and capillaries, lymphatic vessels, articular capsule and ependymocytes. On the other side of the internal environment are the cytoplasmic membranes of the cells with which the intercellular fluid, also included in the GUS, contacts.
Part of the internal environment of the body is formed by blood. It is a fluid that contains shaped elements, proteins, and some elemental substances. Here the mass of enzymatic processes takes place. But the main function of the blood is transport, especially oxygen to the cells and carbon dioxide from them. Therefore in the blood the shaped elements have the largest proportion: red blood cells, platelets, leukocytes. The former are engaged in the transport of oxygen and carbon dioxide, although they are also capable of playing an important role in immune reactions due to active oxygen forms.
Leukocytes in the blood are occupied only with immune responses. They participate in the immune response, regulate its strength and fullness, and also store information about the antigens with which they have been in contact previously. Since part of the internal environment of the body is formed just by the blood, which plays the role of a barrier between body parts in contact with the external environment and cells, the immune function of the blood is the second most important after the transport. However, it requires the use of both shaped elements and plasma proteins.
The third important function of blood is hemostasis.This concept combines several processes that are aimed at preserving the liquid consistency of blood and covering the defects of the vascular wall when they appear. The hemostasis system ensures that the blood flowing through the vessels will be liquid until it is necessary to close the damage to the vessel. Moreover, the internal environment of the human body will not suffer then, although this requires energy expenditure and the activation of platelets, erythrocytes and plasma factors of the coagulation and anticoagulation system.
The second part of the blood is liquid. It consists of water in which proteins, glucose, carbohydrates, lipoproteins, amino acids, vitamins with their carriers and other substances are evenly distributed. Among the proteins emit high molecular weight and low molecular weight. The first are represented by albumin and globulins. These proteins are responsible for the functioning of the immune system, the maintenance of plasma oncotic pressure, the functioning of the coagulation and anticoagulation systems.
Carbohydrates, dissolved in the blood, act as transported energy-intensive substances. This is a nutrient substrate that must enter the extracellular space, from where it will be captured by the cell and processed (oxidized) in its mitochondria.The cell will receive the energy necessary for the work of the systems responsible for the synthesis of proteins and the performance of functions that benefit the whole body. At the same time, amino acids, also dissolved in blood plasma, also penetrate into the cell and are a substrate for protein synthesis. The latter is a tool for the realization by the cell of its hereditary information.
The role of plasma lipoproteins
Another important source of energy, in addition to glucose, is triglyceride. This is a fat that should break down and become an energy carrier for muscle tissue. It is she who, for the most part, is able to process fats. By the way, they contain much more energy than glucose, and therefore are able to provide muscle contraction for a much longer period than glucose.
Fats are transported to the cells through membrane receptors. The molecules of fat absorbed in the intestine are first connected to the chylomicrons, and then they enter the intestinal veins. From there chylomicrons pass into the liver and enter the lungs, where low-density lipoproteins are formed from them. The latter are transport forms in which fats are delivered through the blood into the extracellular fluid to muscle sarcomeres or smooth muscle cells.
Also, blood and extracellular fluid, together with the lymph, of which the internal environment of the human body consists, transports the products of metabolism of both fats, and carbohydrates, and proteins. They are partially contained in the blood that carries them to the place of filtration (kidney) or disposal (liver). Obviously, these biological fluids, which are the media and compartments of the body, play a crucial role in the vital activity of the body. But much more important is the presence of a solvent, that is, water. Only through it can substances be transported, and the cells exist.
It is believed that the composition of the internal environment of the body is approximately constant. Any fluctuations in the concentration of nutrients or metabolic products, changes in temperature or acidity lead to impaired functioning. Sometimes they can cause death. By the way, it is a violation of acidity and acidification of the internal environment of the body is the fundamental and most difficult to correct disruption of life.
This is observed in cases of polyarganous insufficiency, when acute hepatic and renal failure develops.These bodies are designed to dispose of acidic metabolic products, and when this does not occur, there is an immediate threat to the life of the patient. Therefore, in reality, all components of the internal environment of the body are very important. But much more important is the performance of the organs, which also depend on the VSO.
It is the intercellular fluid that reacts first to changes in the concentrations of nutrients or metabolic products. Later, this information enters the blood through mediators secreted by the cells. The latter allegedly transmit a signal to cells in other areas of the body, urging them to take measures to correct the violations that occurred. So far this system is the most effective of all represented in the biosphere.
Lymph is also the internal environment of the body, the functions of which are reduced to the spread of leukocytes throughout the body’s media and the discharge of excess fluid from the interstitial space. Lymph is a fluid containing low molecular weight and high molecular weight proteins, as well as some nutrients.
From the interstitial space, it is discharged through the smallest vessels, which are collected and form lymph nodes.They actively proliferate lymphocytes, which play an important role in the implementation of immune responses. From the lymphatic vessels it collects in the thoracic duct and flows into the left venous angle. Here the fluid returns to the bloodstream.
Synovial fluid and cerebrospinal fluid
Synovial fluid is a variant of the intercellular fluid fraction. Since cells cannot penetrate into the articular capsule, the only way to feed the articular cartilage is synovium. The internal environment of the body are all the articular cavities, because they are not connected with the structures in contact with the external environment.
Also, all the cerebral ventricles of the brain together with the cerebrospinal fluid and subarachnoid space also belong to the VSO. Liquor is already a variant of lymph, since the nervous system does not have its own lymphatic system. Through the cerebrospinal fluid, the brain is cleared of metabolic products, but does not feed on it. The brain is powered by blood, products dissolved in it and bound oxygen.
Through the blood-brain barrier, they penetrate to neurons and glial cells, delivering the necessary substances to them.Metabolic products are diverted through the cerebrospinal fluid and the venous system. And, probably, the most important function of the cerebrospinal fluid is to protect the brain and nervous system from temperature fluctuations and from mechanical damage. Since the fluid actively extinguishes mechanical impacts and shocks, this property is really necessary for the body.
The external and internal environment of the body, despite the structural isolation from each other, are inextricably linked by a functional link. Namely, the external environment is responsible for the entry of substances into the internal, from where it brings metabolic products to the outside. And the internal environment transfers nutrients to the cells, diverting harmful products from them. Thus, homeostasis is maintained, the main characteristic of vital activity. This also means that it is practically impossible to separate the external environment of otragism from the internal.