The importance of the nervous system for the body. Structure of the nervous system

Of all the systems of the body, the nervous is the most important. It depends on it the coordinated work of all other organs, tissues and cells. The main value of the nervous system for the body is that at its expense it functions as a single whole. In addition, it also controls the body's contacts with the external environment.

Man at the expense of this system can think, analyze events. The depth of the nervous system is much more important for the body: it controls everything, including breathing processes, hematopoiesis, hunger and thirst, and it is responsible for all our reflexes, including the most primitive ones. To understand its importance for our body, you should know (at least at a primitive level) its structure.

What is in the nervous system?

It is formed by a neural tissue, which includes neurons and satellite cells (astrocytes). Let's briefly describe their purpose:

• The neuron is the main functional unit of the nervous tissue. It is these cells that are responsible both for thinking and for all other functions of the entire system.
• The satellite cells perform a trophic and supporting function. At present, it is believed that they still play an important role in the mechanism of long-term memory, although this hypothesis needs to be clarified.

We will continue to discuss the structure and significance of the nervous system.

Structure of the neuron

This cell, which is responsible for almost everything that happens in the body, consists of the body and the processes. They are divided into two types: axons and dendrites. The first of them leave the cell in a single copy, long. On the contrary, dendrites differ not very prominent in size, they are highly branched. As a rule, each nerve cell can have several. From the dendrites, the nerve impulses go into the cell.

Axon is distinguished by a long length, practically not branching. It pulses out of the body of the nerve cell. The length of this process can exceed several tens of centimeters. On it signals are transmitted by electric discharges, almost instantaneously.

A small digression. It should be noted that the meaning, structure and functioning of the nervous system are so complex and diverse that scientists are only beginning to guess about many functional features, about some particularly complex biochemical processes that take place in the depth of the central nervous system.

Axons are covered with a shell of fat-like substance, which serves as an insulator. It is the accumulations of these processes that form the white matter of the nervous system. The body of a neuron and dendrites have no shell. Clusters of these objects are called gray matter.

We continue to study the structure and significance of the nervous system. You should clearly imagine that neurons are largely differentiated, there are no universal cells of this type. Let's continue to talk about the importance of the nervous system. The general plan of the nervous system can not be imagined even approximately if one does not know about the structure of the neuron, its functional unit.

What are neurons?

Do not assume that all neurons are the same. On the contrary, they differ greatly in form and function. Sensitive transmits impulses from the senses to the brain. Their bodies are located in the large nerve nodes of the body. By the way, so-called large clusters of neurons outside the brain and spinal cord. The motor species, on the contrary, transmits impulses from the brain to the muscles and internal organs.

Insertion neurons are responsible for the interaction and transfer of information between sensory and motor cells. Their processes are very short, play the role of "layers", do not go beyond the brain. Thus, the brain receives information from all systems and organs of the body.

So, let's sum up the subtotal. What is the main value of the nervous system for the body? We list:

• It receives signals from the senses, the receptors of smell and touch.
• The neurons analyze the information received.
• An appropriate impulse is transmitted to the executive organ (muscle, for example).
• The body adequately responds to the irritating factor of the external environment.

Impulses from the brain and to it are transmitted not only by separate processes of neurons, but also by specialized nerves.

What is the nerves?

In everyday life, we constantly hear this word, but somehow we do not think about its true meaning. But the nervous system and its role in the body are so great that you should know about it!

Nerves are called just the same accumulations of long processes of neurons, which are covered with a special protective coating. If under this "winding" there are processes of motor neurons, then the nerves themselves are called motor nerves. As a rule, nerve trunks contain both dendrites and axons. In this case, they are called mixed. They differ in that they can transmit nerve impulses in both directions.

Departments of the nervous system

It has two main departments: internal and peripheral. The central part includes the head and spinal cord, protected by the bones of the skull and spinal column. Accordingly, peripheral nerves include nerves and separate outgrowths of neurons.

That part of the nervous system that controls the work of skeletal muscles is called somatic. Thus, the value of the nervous system for the body in this case is extremely important: it is "somatics" that allows us to move our arms and legs. The autonomous department of the system is responsible for the work of the internal organs. Its functioning does not obey the conscious will of man. Simply put, you hardly know how to control the process of digestion, slow or speed it up.

Thus, the importance of the nervous system in the regulation of body functions is extremely great: it controls even those processes that most people do not even guess. Of course, if everything is in order with their organism and everything functions in a "regular" mode.

In this department there are two large "structural units": the sympathetic and parasympathetic nervous system. Virtually all internal organs are innervated by the nerve trunks precisely from it. The effect on the body in these departments is diametrically opposite.

For example, sympathy increases contractions of cardiac cross-striped musculature, and parasympathetic slows down this process, it is responsible for digestion. Thus, the role of the parasympathetic nervous system in the body is even more important. She is responsible for breathing and other vital processes.

Reflex

And what is the significance of the nervous system in the absolutely unconditional reaction of man and animal to some irritation of the external environment? Simply put, how is the reflex activity carried out?

As is known, the mechanism that we know as a "reflex arc" is responsible for this. This is the path through which nerve impulses pass at a time when the body responds with a reflex to irritation. It consists of the following parts: the receptor, the sensitive pathway, some part of the nervous system responsible for the reflex, the path through which the signal is coming, and also from the working organ.

This is how great is the importance of the nervous system in the life of a person. When something is violated in it, for a sick person, a real feat can be an independent tying of shoelaces. It's amazing how few people think about the importance of nervous tissue!

On the segments of the reflex arc

Each arc begins with a sensitive receptor. Each of them perceives only a certain kind of stimulus. Receptors are responsible for converting the effects of the external environment into nerve impulses. The impulses that drive the skeletal musculature, trigger some important processes and perform an equally important function, are of a purely electrical nature. With the help of a sensitive neuron, impulses are transmitted to the central nervous system.

Note that almost all reflex arcs have intercalary neurons.

Many believe that the reflex reaction is a completely unconscious process, which, once fixed, remains completely unchanged. But this is far from the case. The fact is that the signal received from the receptor, the nervous system does not just accept, but conducts its analysis, evaluating the effectiveness of the reaction. Simply put, this is how people during their training bring their actions not only to reflex automatism, but they also do it perfectly.

Now let's talk about the significance of the nervous system in the context of the discussion of the spinal cord. Some believe that it serves only to transfer impulses from the brain to the lower sections. The biggest mistake, because the role of this body is much more important.

Structure of the spinal cord

The spinal cord is located in the spinal canal. Limited and protected by physical cavities - the skull bones, as well as the vertebral column itself. The theoretical (anatomical) boundary between the spinal cord and the brain passes between the occipital bone and the atlas.

In humans, it has the appearance of a white cord, whose diameter is approximately 1 centimeter. The canal itself is filled with liquor, cerebrospinal fluid. On the surface of the organ itself there are two deep longitudinal furrows that divide it into the right and left parts. If you cut your brain in half, you can see a pretty beautiful pattern that resembles a butterfly.

Its body is formed by neurons (intercalary and motor). As we have already said, the white substance that covers them from all sides is a long process of neurons. They, passing along the spinal cord up and down, form an ascending and descending channels.

What are the functions of the spinal cord?

It has two main tasks: reflexes and the role of the conductor path. Due to the reflex function, we have the ability to perform many movements. All contractions of the skeletal muscles of the body (except the muscles of the head) are somehow connected with reflex arcs, which directly depend on the activity of the spinal cord.

In other words, the role of the nervous system in the vital activity of the organism is extremely multifaceted: in the regulation of the work of organs and systems, its departments sometimes participate, of which many remember very seldom.

We are not exaggerating at all! Indeed, the spinal cord in the company with its "head counterpart" regulate the correctness of the work of an incredible number of organs: the digestive system and heart, excretory system and reproduction organs. Due to the white matter, synchronization is carried out, and their reaction to external and internal stimuli is fully instantaneous.

Important! Do not forget that the spinal cord is still subject to the head in everything. It is not uncommon for a person to completely break off the connection between the brain and spinal cord as a result of trauma, accident or illness. The first one works absolutely perfectly in such cases. That's just almost all the reflexes, whose zones are located below, completely disappear.

Such people can at best move their hands, slightly turn their heads, but the entire lower body is completely immobile and devoid of any kind of sensitivity.

Brain

Located in the skull. It is subdivided into the following divisions: the medulla oblongata, the cerebellum, the bridge, the intermediate and middle departments, and the hemisphere. As in the previous case, there is a white and gray substance. White binds each other as part of the brain itself, as well as its with the dorsal region. Due to this, the entire CNS functions as a single whole.

Unlike the spinal cord, here gray matter emerges on the surface of the organ, forming its bark, cortex.

The medulla oblongata is actually the extension of the dorsal region, it is necessary to connect these parts of the nervous system with each other. He is responsible for breathing, digestion and other unconscious functions, and therefore his damage is mortally dangerous for life.

Value of individual components

The cerebellum regulates the motor functions. The middle brain serves as a "transshipment point" for many reflex arcs. The oblong brain, bridge and middle brain form a kind of trunk, connecting various departments and performing many reflex functions. The bark is the youngest and most important department. It is through it that we think, think, and store our memories. Trauma to the cortex is fraught with complete loss of personality.

Often, people who have long been in a state of clinical death, drowned, after especially terrible accidents, were alive as a result of intensive cardiac and pulmonary resuscitation. That's only life, this state is extremely difficult. The neurons of the cortex die very quickly, after which the person turns into a "vegetable". He can not talk, he has no memory of a past life (with rare exceptions), he can not service himself at all.

That's what the nervous system has in the vital activity of the body.