Of all body systems, the nervous system is the most important. The coordinated work of all other organs, tissues and cells depends on it. The main value of the nervous system for the body is that at its expense, it functions as a whole. In addition, it also controls the body's contacts with the environment.
A person at the expense of this system can think, analyze events. The deep significance of the nervous system for the body is much more important: it controls everything, including the processes of respiration, blood formation, 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 composition of the nervous system?
It is formed by nerve tissue, which includes neurons and satellite cells (astrocytes). Let us briefly describe their purpose:
- A neuron is the main functional unit of nerve tissue. It is these cells that are responsible both for thinking and for all other functions of the entire system.
- 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 continue to discuss the structure and significance of the nervous system.
Neuron structure
This cell, which is responsible for almost everything that happens in the body, consists of the body and processes. They are divided into two types: axons and dendrites. The first of them depart from the cell in a single copy, long. On the contrary, dendrites are not very prominent in size, highly branched. As a rule, each nerve cell may have several. On dendrites, nerve impulses go into the cell.
The axon is distinguished by a large length, practically does not branch. On it, impulses exit the body of a nerve cell. The length of this process can exceed several tens of centimeters. On it, signals are transmitted using electrical discharges, almost instantly.
A small digression. It should be noted that the significance, structure and functioning of the nervous system are so complex and diverse that scientists are just beginning to guess about many functional features, about some particularly complex biochemical processes that occur in the depths of the central nervous system.
Axons are coated with a shell of a fat-like substance that serves as an insulator. It is the clusters of these processes that form the white matter of the nervous system. The body of the neuron and dendrites have no shell. The accumulations 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. We continue to talk about the importance of the nervous system. It is impossible to imagine a general plan of the nervous system even approximately if you do not know about the structure of the neuron, its functional unit.
What are neurons?
It should not be assumed that all neurons are the same. On the contrary, they are very different from each other in their form and functions. Sensitive transmit impulses from the senses to the brain. Their bodies are located in the large nerve nodes of the body. By the way, these are the names of large clusters of neurons outside the brain and spinal cord. The motor variety, in contrast, 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, to summarize the intermediate result. What is the main importance of the nervous system for the body? We list:
- It receives signals from the senses, receptors of smell and touch.
- In neurons, the analysis of the received information is performed.
- An appropriate impulse is transmitted to the executive organ (muscle, for example).
- The body adequately responds to the irritating environmental factor.
Impulses from and to the brain are transmitted not only along individual processes of neurons, but also along specialized nerves.
What are nerves?
In everyday life, we constantly hear this word, but somehow we don’t think about its true meaning. But the nervous system and its role in the body are so great that you should be aware of this!
Accumulations of long processes of neurons that are covered with a special protective shell are called nerves. 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 brain and spinal cord, protected by the bones of the skull and spinal column. Accordingly, the nerve nodes include nerves and individual processes of neurons in the periphery .
The part of the nervous system that controls the work of skeletal muscles is called somatic. Thus, the importance of the nervous system for the body in this case is extremely important: it is the “somatic” that allows us to move our arms and legs. The autonomous department of the system is responsible for the work of internal organs. Its functioning does not obey the conscious will of man. Simply put, you hardly know how to control the digestion process, slow down or speed it up.
Thus, the importance of the nervous system in the regulation of body functions is extremely large: it controls even those processes that most people do not even know about. Of course, if everything is in order with their body and everything functions in the “regular” mode.
There are two large “structural units” in this section: the sympathetic and parasympathetic nervous systems. Almost all internal organs are innervated by the trunks of nerves from her. The effect on the body in these departments is diametrically opposite.
For example, sympathy enhances the contraction of the heart striated muscle, and parasympathetics 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 completely unconditional reaction of man and animal to some kind of stimulation of the external environment? Simply put, how is reflex activity carried out?
As you know, the mechanism that we know as the “reflex arc” is responsible for this. This is the path along which nerve impulses pass at the moment when the body responds with a reflex to irritation. It consists of the following sections: the receptor, the sensitive pathway, some part of the nervous system responsible for the reflex, the pathway along which the signal goes, and also from the working organ.
This is how great the importance of the nervous system in human life is. When something is broken in it, for a sick person a real feat may be self- tying shoelaces. It's amazing how few people think about the importance of nerve tissue!
About segments of a reflex arc
Each arc begins with a sensitive receptor. Each of them perceives only some specific type of stimulus. Receptors are responsible for converting environmental influences into nerve impulses. Impulses that drive skeletal muscle, start some important processes and perform an equally important function, have a purely electrical nature. Using a sensitive neuron, impulses are transmitted to the central nervous system.
Note that almost all reflex arcs incorporate intercalary neurons.
Many believe that a reflex reaction is a completely unconscious process that, once entrenched, remains completely unchanged. But this is far from the case. The fact is that the nervous system not only receives the signal received from the receptor, but carries out its analysis, evaluating the effectiveness of the reaction. Simply put, this is how people during training bring their actions not only to reflex automatism, but also do it perfectly.
Now let's talk about the importance of the nervous system in the context of the discussion of the spinal cord. Some believe that it serves solely to transmit impulses from the brain to the lower sections. The biggest mistake, since the role of this body is much more important.
Spinal cord structure
The spinal cord is located in the spinal canal. It is limited and protected by physical cavities - the bones of the skull, as well as the spinal column itself. The theoretical (anatomical) border between the spinal cord and the brain runs between the occipital bone and the atlas.
In humans, it has the appearance of a white cord, the diameter of which is approximately 1 centimeter. The canal itself is filled with cerebrospinal fluid, cerebrospinal fluid. On the surface of the organ itself there are two deep longitudinal grooves that divide it into the right and left parts. If you cut the brain in half, you can see a pretty beautiful pattern that resembles a butterfly.
Her body is formed by neurons (intercalary and motor). As we already said, the white matter that covers them from all sides is a long process of neurons. They, passing along the spinal cord up and down, form the ascending and descending channels.
What are the functions of the spinal cord?
He has two main tasks: reflexes and the role of the pathway. Due to the reflex function, we are able to make many movements. All contractions of the skeletal muscles of the body (except for 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 functions of the body is extremely multifaceted: sometimes its departments are involved in the regulation of the functioning of organs and systems, which many people rarely remember.
We are not exaggerating at all! Indeed, the spinal cord in the company with its "head colleague" regulates the correct operation of an incredible number of organs: the digestive system and the heart, excretory system and reproductive organs. Due to the white matter, synchronization is carried out, their reaction to external and internal stimuli is completely instantaneous.
Important! Do not forget that the spinal cord is nevertheless subordinate to the brain in everything. There are frequent cases when, as a result of an injury, accident or illness, a person completely lost contact between the brain and spinal cord. The first in such cases works absolutely normal. That's just almost all the reflexes, the zones of which are located below, completely disappear.
Such people can at best move their hands, turn their heads slightly, but their entire lower body is completely motionless and devoid of any sensitivity.
Brain
Located in the cranium. It is divided into the following departments: medulla oblongata, cerebellum, bridge, intermediate and middle sections, as well as the hemispheres. As in the previous case, there is a white and gray matter. White connects both parts of the brain itself and its spinal cord. Thanks to this, the entire central nervous system functions as a whole.
Unlike the spinal cord, here gray matter comes to the surface of the organ, forming its cortex, cortex.
The medulla oblongata is actually a continuation of the spinal section; it is necessary for the connection between these parts of the nervous system. He is responsible for breathing, digestion and other unconscious functions, and therefore his damage is deadly to life.
The value of the individual components
The cerebellum regulates motor functions. The midbrain serves as a “transfer point” for many reflex arcs. The medulla oblongata, the bridge and the midbrain form a kind of trunk connecting the various departments and performing many reflex functions. Bark is the youngest and most important department. It is at the expense of her that we think, think, keep our memories. Cortex injury is fraught with complete loss of personality.
There are frequent cases when people who have been in a state of clinical death for a long time, drowned, after especially terrible accidents, were found to be alive as a result of intensive cardiac and pulmonary resuscitation. It’s extremely difficult to call such a state life. The neurons of the cortex die very quickly, after which the person turns into a "vegetable". He cannot speak, he has no memory of a past life (with the rarest exceptions), he cannot serve himself at all.
This is what the nervous system has in the life of an organism.