Adaptation-trophic function

One of the departments of the central nervous system, called vegetative, consists of several parts. One of them is the sympathetic nervous system. Functional and morphological features allow us to conditionally divide it into several departments. Another branch of the autonomic NA is the parasympathetic nervous system. In this article we will consider what a trophic function is.

About the nervous system

In the life of absolutely any living organism, a number of important functions are performed by the nervous system. Therefore, its significance is very great. The nervous system itself is quite complex and includes different departments, several subspecies. Each of them performs a number of specific functions, characteristic for each of the departments. It is interesting that the very concept of the sympathetic nervous system was first used in 1732.At the very beginning this term was used to denote the entire autonomic nervous system as a whole. However, with the development of medicine and the accumulation of scientific knowledge, it became clear that the sympathetic nervous system carries a wider range of functions. That's why this concept was used in relation to only one of the departments of the autonomic nervous system. The trophic function of the nervous system will be presented below.

Sympathetic NS

If you dwell on specific values, it becomes clear that the sympathetic nervous system is characterized by quite interesting functions - it is responsible for the process of consumption of body resources, and also mobilizes its internal forces in the occurrence of emergency situations. If a need arises, the sympathetic system significantly increases the expenditure of energy resources in order for the organism to continue its normal functioning and fulfill certain tasks. In the event that a conversation arises about the fact that the human body has hidden opportunities, this process is implied. The state of a person directly depends on how sympathetic the system copes with its tasks.

Parasympathetic NS

However, such conditions cause great stress for the body, and in this condition it can not function for a long time in normal mode. Parasympathetic system, which enters the business and allows to restore and accumulate body resources, is of great importance here, which, in turn, allows not to limit its possibilities. Sympathetic and parasympathetic nervous systems allow the human body to lead normal life activity under various conditions. They are in close interconnection and are complementary to each other. But what does the trophic function of HC mean? About this further.

Anatomical device

Sympathetic NA has a rather complex and branched structure. Its central part is located in the spinal cord, and the peripheral connects the various nerve nodes and nerve endings of the body. All the endings of the nerves of the sympathetic system are connected to the plexus and concentrated in the innervated tissues.

The peripheral part of the system is formed by a variety of sensitive efferent neurons, which have specific processes. These processes are distant from the spinal cord and are located mainly in the pre-invertebrate and near-vertebral nodes.

The functions of the sympathetic system

As it was mentioned, the activation of the sympathetic system occurs when the body gets into a stressful situation. Some sources call it the reactive sympathetic nervous system. This name is due to the fact that it suggests the emergence of a certain reaction of the body to external influences. This is its trophic function.

In case of a stressful situation, the adrenal glands immediately begin to excrete adrenaline. It is the main substance that allows a person to react better and faster, responding to stress. A similar situation can occur during exercise. The release of adrenaline allows you to better deal with it. Adrenaline contributes to the strengthening of the sympathetic system, and it, in turn, provides resources for increased energy consumption. The very secretion of adrenaline is not an energy resource, but only contributes to the stimulation of human organs and senses.

The main function of

The main function of the sympathetic NS is the adaptation-trophic function.

Let's consider it in more details.

Scientists-biologists have long been convinced that the purely somatic nervous system provides the regulation of the activity of skeletal muscles. This conviction was shaken only at the beginning of the 20th century.

A well-known fact: with prolonged work, muscle fatigue occurs. The force of contractions gradually fades, and they can stop at all. The working capacity of the muscle has the property of recovering after a short rest. For a long time, the causes of this phenomenon were unknown.

In 1927, Orbeli LA experimentally established the following: if you bring the frog's foot to a complete cessation of movements, that is, before fatigue, by prolonged exposure to the motor nerve, and then, without stopping the motor stimulation, begin to simultaneously irritate and nerve the sympathetic system, the limb will be quickly restored. It turns out, the connection of influence on the sympathetic system changes the functionality of the muscle, which is tired. There is elimination of fatigue and restoration of its efficiency. This is the trophic function of nerve cells.

Effect on muscle fibers

Scientists have found that the nerves of the sympathetic system exert a strong influence on muscle fibers, in particular, on their ability to conduct electrical currents, and also on the level of excitability of the motor nerve. Under the influence of sympathetic innervation, the composition and quantity of chemical compounds contained in the muscle change and play an important role in the performance of its activity. These compounds include lactic acid, glycogen, creatine, phosphates. In accordance with these data, it became possible to conclude that the sympathetic system stimulates the appearance of certain physico-chemical changes in skeletal muscles, has a regulating effect on the sensitivity of the muscle to the resulting motor impulses that come through the fibers of the somatic system. It is the sympathetic system that adapts the muscle tissue to the exercise of the loads that can occur under different circumstances. There was an opinion that the work of a tired muscle is amplified by the action of the sympathetic nerve due to increased blood flow. However, the conducted experiments did not confirm this opinion. This is how the trophic function of the neuron works.

Through special studies it was possible to establish that direct sympathetic excitability in vertebrate organisms is absent. Thus, the influence of the sympathetic nature on the skeletal muscle is realized only through the diffusion of the mediator or other substances that are distinguished by the vasomotor terminals of the sympathetic system. This conclusion can be easily confirmed by a simple experiment. If the muscle is placed in a solution or perfused with its vessels, and then begins to affect the sympathetic nerve, then in the solution or in the perfusate, the unknown nature of the substance is observed. If these substances are introduced into other muscles, they cause a sympathetic effect.

This mechanism is also confirmed by a large latent period and its considerable duration before the effect occurs. For the appearance of adaptive-trophic function, it does not take a long time in those organs that are endowed with direct sympathetic irritability, for example, the heart and other internal organs.

Confirming facts

The facts proving neurotrophic regulation from the sympathetic system were obtained during various studies on skeletal muscle tissue. The studies included functional overloads, denervation, regeneration, cross-connection of nerves that are connected to different types of muscle fibers. As a result of the research, it was concluded that the trophic function is performed by metabolic processes that maintain a normal muscular structure and ensure its needs during the performance of specific loads. The same metabolic processes help to restore the necessary resources after the work of the muscle is stopped. The work of such processes is due to a number of biological regulatory substances. There is evidence that for the appearance of a trophic action, it is necessary to transport the necessary substances from the cell body to the executive body.

It is universally recognized that the importance of neurotransmitters is not limited to participation in the process of impulse transmission. They also affect the vital activity of the organs being excited, participating in the energy supply of tissues.

For example, catecholamines participate in such a process as the exercise of trophic function. In the blood, the level of energy substrates increases, which leads to a rapid and intensive influence on metabolic processes.

Conclusion

It is known that sensitive nerve fibers also exhibit an adaptive-trophic effect. Scientists have found that in the endings of sensitive fibers contain various kinds of substances of a neuroactive nature, for example, neuropeptides. Most often there are P-neuropeptides, as well as peptides that are associated with the calcitonin gene. Such peptides, after isolation from the nerve endings, can exert a trophic influence on the tissues surrounding them.