The structure of the function of the nervous system. Nervous system, structure and functions. Nerves. Propagation of a nerve impulse

The human nervous system is an important part of the body, which is responsible for many ongoing processes. Her diseases have a bad effect on the human condition. It regulates the activity and interaction of all systems and organs. With the current environmental background and constant stress, it is necessary to pay serious attention to the daily routine and proper nutrition in order to avoid potential health problems.

general information

The nervous system affects the functional interaction of all human systems and organs, as well as the connection of the body with the outside world. Its structural unit - a neuron - is a cell with specific processes. Neural circuits are built from these elements. The nervous system is divided into central and peripheral. The first includes the brain and spinal cord, and the second - all the nerves and nerve nodes extending from them.

somatic nervous system

In addition, the nervous system is divided into somatic and autonomic. The somatic system is responsible for the interaction of the body with the outside world, for the ability to move independently and for sensitivity, which is provided with the help of the sense organs and some nerve endings. The ability of a person to move is provided by the control of skeletal and muscle mass, which is carried out with the help of the nervous system. Scientists also call this system animal, because only animals can move and have sensitivity.

autonomic nervous system

This system is responsible for the internal state of the body, that is, for:

The human autonomic nervous system, in turn, is divided into sympathetic and parasympathetic. The first is responsible for the pulse, blood pressure, bronchi and so on. Its work is controlled by the spinal centers, from which come the sympathetic fibers located in the lateral horns. Parasympathetic is responsible for the work of the bladder, rectum, genital organs and for a number of nerve endings. Such multifunctionality of the system is explained by the fact that its work is carried out both with the help of the sacral part of the brain and through its trunk. The control of these systems is carried out by specific vegetative apparatuses that are located in the brain.

Diseases

The human nervous system is extremely susceptible to outside influence, there are a variety of reasons that can cause its diseases. Most often, the vegetative system suffers due to the weather, while a person can feel bad both in too hot times and in cold winters. There are a number of characteristic symptoms for such diseases. For example, a person turns red or pale, the pulse speeds up, or excessive sweating begins. In addition, such diseases can be acquired.

How do these diseases appear?

They can develop due to head trauma, or arsenic, or due to a complex and dangerous infectious disease. Such diseases can also develop due to overwork, due to a lack of vitamins, with mental disorders or constant stress.

Care must be taken under dangerous working conditions, which can also affect the development of diseases of the autonomic nervous system. In addition, such diseases can masquerade as others, some of them resemble heart disease.

central nervous system

It is formed from two elements: the spinal cord and the brain. The first of them looks like a cord, slightly flattened in the middle. In an adult, its size varies from 41 to 45 cm, and the weight reaches only 30 grams. The spinal cord is completely surrounded by membranes that are located in a specific canal. The thickness of the spinal cord does not change along its entire length, except for two places, which are called the cervical and lumbar thickenings. It is here that the nerves of the upper as well as the lower extremities are formed. It is subdivided into such departments as cervical, lumbar, thoracic and sacral.

Brain

It is located in the human cranium and is divided into two components: the left and right hemispheres. In addition to these parts, the trunk and cerebellum are also distinguished. Biologists were able to determine that the brain of an adult male is 100 mg heavier than a female. This is due solely to the fact that all parts of the body of the stronger sex are larger than female in physical parameters due to evolution.

The fetal brain begins to actively grow even before birth, in the womb. It stops its development only when a person reaches 20 years of age. In addition, in old age, towards the end of life, it becomes a little easier.

Sections of the brain

There are five main parts of the brain:

In the case of a traumatic brain injury, the central nervous system of a person can be seriously affected, and this has a bad effect on the mental state of a person. With such disorders, patients may have voices in their heads that are not so easy to get rid of.

Shells of the brain

Three types of membranes cover the brain and spinal cord:

• The hard shell covers the outside of the spinal cord. In shape, it is very similar to a bag. It also functions as the periosteum of the skull.
• The arachnoid is a substance that practically adheres to the solid. Neither the dura mater nor the arachnoid contains blood vessels.
• The pia mater is a collection of nerves and vessels that feed both brains.

Brain Functions

This is a very complex part of the body, on which the entire human nervous system depends. Even considering that a huge number of scientists are studying the problems of the brain, all its functions have not been fully studied yet. The most difficult puzzle for science is the study of the features of the visual system. It is still unclear how and with what parts of the brain we have the ability to see. People far from science mistakenly believe that this happens solely with the help of the eyes, but this is absolutely not the case.

Scientists who study this issue believe that the eyes only perceive the signals that the surrounding world sends, and in turn transmit them to the brain. Receiving a signal, it creates a visual picture, that is, in fact, we see what our brain shows. Similarly, it happens with hearing, in fact, the ear only perceives the sound signals received through the brain.

Conclusion

Currently, diseases of the autonomic system are very common in the younger generation. This is due to many factors, such as poor environmental conditions, improper daily routine or irregular and improper diet. To avoid such problems, it is recommended to carefully monitor your schedule, avoid various stresses and overwork. After all, the health of the central nervous system is responsible for the state of the whole organism, otherwise such problems can provoke serious disturbances in the work of other important organs.

The nervous system controls the activity of all systems and organs and ensures the connection of the body with the external environment.

The structure of the nervous system

The structural unit of the nervous system is the neuron - a nerve cell with processes. In general, the structure of the nervous system is a collection of neurons that are constantly in contact with each other using special mechanisms - synapses. The following types of neurons differ in function and structure:

• Sensitive or receptor;
• Effector - motor neurons that send an impulse to the executive organs (effectors);
• Closing or plug-in (conductor).

Conventionally, the structure of the nervous system can be divided into two large sections - somatic (or animal) and vegetative (or autonomous). The somatic system is primarily responsible for the connection of the body with the external environment, providing movement, sensitivity and contraction of skeletal muscles. The vegetative system affects the growth processes (respiration, metabolism, excretion, etc.). Both systems have a very close relationship, only the autonomic nervous system is more independent and does not depend on the will of a person. That is why it is also called autonomous. The autonomous system is divided into sympathetic and parasympathetic.

The entire nervous system consists of the central and peripheral. The central part includes the spinal cord and brain, and the peripheral system represents the outgoing nerve fibers from the brain and spinal cord. If you look at the brain in section, you can see that it consists of white and gray matter.

Gray matter is an accumulation of nerve cells (with the initial sections of processes extending from their bodies). Separate groups of gray matter are also called nuclei.

White matter consists of nerve fibers covered with myelin sheath (processes of nerve cells from which gray matter is formed). In the spinal cord and brain, nerve fibers form pathways.

Peripheral nerves are divided into motor, sensory and mixed, depending on what fibers they consist of (motor or sensory). The bodies of neurons, whose processes are made up of sensory nerves, are located in ganglions outside the brain. The bodies of motor neurons are located in the motor nuclei of the brain and the anterior horns of the spinal cord.

Functions of the nervous system

The nervous system has different effects on the organs. The three main functions of the nervous system are:

• Starting, causing or stopping the function of an organ (secretion of the gland, muscle contraction, etc.);
• Vasomotor, which allows you to change the width of the lumen of the vessels, thereby regulating the flow of blood to the organ;
• Trophic, lowering or increasing metabolism, and, consequently, the consumption of oxygen and nutrients. This allows you to constantly coordinate the functional state of the body and its need for oxygen and nutrients. When impulses are sent along the motor fibers to the working skeletal muscle, causing its contraction, then impulses are simultaneously received that increase metabolism and dilate blood vessels, which makes it possible to provide energy for performing muscle work.

Diseases of the nervous system

Together with the endocrine glands, the nervous system plays a crucial role in the functioning of the body. It is responsible for the coordinated work of all systems and organs of the human body and unites the spinal cord, brain and peripheral system. Motor activity and sensitivity of the body is supported by nerve endings. And thanks to the autonomic system, the cardiovascular system and other organs are inverted.

Therefore, a violation of the functions of the nervous system affects the work of all systems and organs.

All diseases of the nervous system can be divided into infectious, hereditary, vascular, traumatic and chronically progressive.

Hereditary diseases are genomic and chromosomal. The most famous and common chromosomal disease is Down's disease. This disease is characterized by the following symptoms: a violation of the musculoskeletal system, the endocrine system, lack of mental abilities.

Traumatic lesions of the nervous system occur due to bruises and injuries, or when squeezing the brain or spinal cord. Such diseases are usually accompanied by vomiting, nausea, memory loss, disorders of consciousness, loss of sensitivity.

Vascular diseases mainly develop against the background of atherosclerosis or hypertension. This category includes chronic cerebrovascular insufficiency, cerebrovascular accident. Characterized by the following symptoms: attacks of vomiting and nausea, headache, impaired motor activity, decreased sensitivity.

Chronically progressive diseases, as a rule, develop as a result of metabolic disorders, exposure to infection, intoxication of the body, or due to abnormalities in the structure of the nervous system. Such diseases include sclerosis, myasthenia, etc. These diseases usually progress gradually, reducing the efficiency of some systems and organs.

Causes of diseases of the nervous system:

The placental route of transmission of diseases of the nervous system during pregnancy (cytomegalovirus, rubella), as well as through the peripheral system (poliomyelitis, rabies, herpes, meningoencephalitis) is also possible.

In addition, the nervous system is negatively affected by endocrine, heart, kidney diseases, malnutrition, chemicals and drugs, heavy metals.

Nervous system is a set of special structures that unites and coordinates the activity of all organs and systems of the body in constant interaction with the external environment.

Significance of the nervous system:

Maintaining the constancy of the composition of the internal environment of the body.

Coordination of the work of bodies.

Recognition of the external environment to meet needs. Orientation in the external environment.

Ensuring conscious regulation of behavior. Psyche - speech, thinking, social behavior.

The structure of the human nervous system diagram

The human nervous system is divided into the central nervous system (includes the brain and spinal cord) and the peripheral nervous system (includes nerve endings, nerves, nerve nodes).

Functional division of the nervous system

Functionally, the nervous system is divided into Somatic (subordinate to the will of man) and Autonomous (vegetative, which is not subject to the will of man). The somatic nervous system regulates the work of skeletal muscles, its motor centers are located in the cerebral cortex. The autonomic or autonomic nervous system regulates the functioning of internal organs, glands, blood vessels, and the heart. Its autonomic centers are located in the hypothalamus.

The autonomic system, in turn, is divided into sympathetic and parasympathetic systems. The sympathetic system is activated during intense work that requires energy expenditure. The parasympathetic system contributes to the restoration of energy reserves during sleep and rest.

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The source of information:

Biology in tables and diagrams. / Edition 2e, - St. Petersburg: 2004.

Rezanova E.A. Human biology. In tables and diagrams./ M.: 2008.

The human nervous system is a stimulator of the muscular system, which we talked about in. As we already know, muscles are needed to move parts of the body in space, and we even studied specifically which muscles are designed for which work. But what powers the muscles? What and how makes them work? This will be discussed in this article, from which you will draw the necessary theoretical minimum for mastering the topic indicated in the title of the article.

First of all, it is worth saying that the nervous system is designed to transmit information and commands to our body. The main functions of the human nervous system are the perception of changes within the body and the space surrounding it, the interpretation of these changes and the response to them in the form of a certain form (including muscle contraction).

Nervous system- a set of different, interacting nervous structures, which, along with the endocrine system, provides coordinated regulation of the work of most of the body's systems, as well as a response to changes in the conditions of the external and internal environment. This system combines sensitization, motor activity and the correct functioning of such systems as endocrine, immune and not only.

The structure of the nervous system

Excitability, irritability and conductivity are characterized as functions of time, that is, it is a process that occurs from irritation to the appearance of an organ response. The propagation of a nerve impulse in the nerve fiber occurs due to the transition of local foci of excitation to neighboring inactive areas of the nerve fiber. The human nervous system has the property of transforming and generating the energies of the external and internal environment and transforming them into a nervous process.

The structure of the human nervous system: 1- brachial plexus; 2- musculocutaneous nerve; 3- radial nerve; 4- median nerve; 5- ilio-hypogastric nerve; 6- femoral-genital nerve; 7- locking nerve; 8- ulnar nerve; 9- common peroneal nerve; 10 - deep peroneal nerve; 11- superficial nerve; 12- brain; 13- cerebellum; 14- spinal cord; 15- intercostal nerves; 16 - hypochondrium nerve; 17- lumbar plexus; 18 - sacral plexus; 19- femoral nerve; 20 - genital nerve; 21- sciatic nerve; 22 - muscular branches of the femoral nerves; 23 - saphenous nerve; 24- tibial nerve

The nervous system functions as a whole with the sense organs and is controlled by the brain. The largest part of the latter is called the cerebral hemispheres (in the occipital region of the skull there are two smaller hemispheres of the cerebellum). The brain is connected to the spinal cord. The right and left cerebral hemispheres are interconnected by a compact bundle of nerve fibers called the corpus callosum.

Spinal cord- the main nerve trunk of the body - passes through the canal formed by the openings of the vertebrae, and stretches from the brain to the sacral spine. From each side of the spinal cord, nerves depart symmetrically to different parts of the body. Touch in general terms is provided by certain nerve fibers, the innumerable endings of which are located in the skin.

Classification of the nervous system

The so-called types of the human nervous system can be represented as follows. The whole integral system is conditionally formed: the central nervous system - CNS, which includes the brain and spinal cord, and the peripheral nervous system - PNS, which includes numerous nerves extending from the brain and spinal cord. The skin, joints, ligaments, muscles, internal organs and sensory organs send input signals to the CNS via PNS neurons. At the same time, outgoing signals from the central NS, the peripheral NS sends to the muscles. As a visual material, below, in a logically structured way, the entire human nervous system (diagram) is presented.

central nervous system- the basis of the human nervous system, which consists of neurons and their processes. The main and characteristic function of the central nervous system is the implementation of reflective reactions of various degrees of complexity, which are called reflexes. The lower and middle sections of the central nervous system - the spinal cord, medulla oblongata, midbrain, diencephalon and cerebellum - control the activity of individual organs and systems of the body, implement communication and interaction between them, ensure the integrity of the body and its correct functioning. The highest department of the central nervous system - the cerebral cortex and the nearest subcortical formations - for the most part controls the communication and interaction of the body as an integral structure with the outside world.

Peripheral nervous system- is a conditionally allocated part of the nervous system, which is located outside the brain and spinal cord. Includes nerves and plexuses of the autonomic nervous system, connecting the central nervous system with the organs of the body. Unlike the CNS, the PNS is not protected by bones and can be subject to mechanical damage. In turn, the peripheral nervous system itself is divided into somatic and autonomic.

• somatic nervous system- part of the human nervous system, which is a complex of sensory and motor nerve fibers responsible for the excitation of muscles, including skin and joints. She also manages the coordination of body movements, and the receipt and transmission of external stimuli. This system performs actions that a person controls consciously.
• autonomic nervous system divided into sympathetic and parasympathetic. The sympathetic nervous system governs the response to danger or stress and, among other things, can cause an increase in heart rate, an increase in blood pressure, and excitation of the senses by increasing the level of adrenaline in the blood. The parasympathetic nervous system, in turn, controls the state of rest, and regulates pupillary contraction, slowing of the heart rate, dilation of blood vessels, and stimulation of the digestive and genitourinary systems.

Above you can see a logically structured diagram, which shows the parts of the human nervous system, in the order corresponding to the above material.

The structure and functions of neurons

All movements and exercises are controlled by the nervous system. The main structural and functional unit of the nervous system (both central and peripheral) is the neuron. Neurons are excitable cells that are capable of generating and transmitting electrical impulses (action potentials).

The structure of the nerve cell: 1- cell body; 2- dendrites; 3- cell nucleus; 4- myelin sheath; 5- axon; 6- end of the axon; 7- synaptic thickening

The functional unit of the neuromuscular system is the motor unit, which consists of a motor neuron and the muscle fibers innervated by it. Actually, the work of the human nervous system on the example of the process of muscle innervation occurs as follows.

The cell membrane of the nerve and muscle fiber is polarized, that is, there is a potential difference across it. Inside the cell contains a high concentration of potassium ions (K), and outside - sodium ions (Na). At rest, the potential difference between the inner and outer side of the cell membrane does not lead to the appearance of an electric charge. This defined value is the resting potential. Due to changes in the external environment of the cell, the potential on its membrane constantly fluctuates, and if it rises, and the cell reaches its electrical threshold of excitation, there is a sharp change in the electrical charge of the membrane, and it begins to conduct an action potential along the axon to the innervated muscle. By the way, in large muscle groups, one motor nerve can innervate up to 2-3 thousand muscle fibers.

In the diagram below, you can see an example of how a nerve impulse travels from the moment a stimulus occurs to receiving a response to it in each individual system.

Nerves are connected to each other through synapses, and to muscles through neuromuscular junctions. Synapse- this is the place of contact between two nerve cells, and - the process of transmitting an electrical impulse from a nerve to a muscle.

synaptic connection: 1- neural impulse; 2- receiving neuron; 3- axon branch; 4- synaptic plaque; 5- synaptic cleft; 6 - neurotransmitter molecules; 7- cell receptors; 8 - dendrite of the receiving neuron; 9- synaptic vesicles

Neuromuscular contact: 1 - neuron; 2- nerve fiber; 3- neuromuscular contact; 4- motor neuron; 5- muscle; 6- myofibrils

Thus, as we have already said, the process of physical activity in general and muscle contraction in particular is completely controlled by the nervous system.

Conclusion

Today we learned about the purpose, structure and classification of the human nervous system, as well as how it is related to its motor activity and how it affects the work of the whole organism as a whole. Since the nervous system is involved in the regulation of the activity of all organs and systems of the human body, including, and possibly, first of all, the cardiovascular system, in the next article from the series on the systems of the human body, we will move on to its consideration.