During this lesson we will become familiar with the structure and functioning of the nervous system. We will also talk about its meaning.
Topic: Nervous and endocrine system
Lesson: The meaning, structure and functioning of the nervous system
Nervous system
Nervous system- one of the main systems that makes our body not just the sum of billions of cells, but a unique single organism.
The nervous system regulates and coordinates the work of all systems and organs, maintains the constancy of the internal environment of the body, and allows a person to successfully survive in difficult, constantly changing conditions.
Of course, the nervous system does not cope with this alone. The most important systems that ensure the integrity of our body are also the endocrine and immune systems. However, when speaking about the regulatory systems of the human body, we primarily mean the nervous system. The fact is that she is the first to respond to changes in the situation, and her reaction is the fastest and most targeted. The nervous system is characterized by the precise direction of nerve impulses and high speed of information transmission. It is the work of this system that serves as the basis for human mental activity, his thinking, speech, and complex forms of behavior.
Nervous tissue
The basis of the nervous system - nerve tissue. Nerve tissue consists of nerve cells - neurons and auxiliary neuroglial cells, or companion cells. Auxiliary cells are located between neurons and make up the intercellular substance of nervous tissue. Perform supporting, protective and nutritional functions.
Neuron- the main structural and functional unit of nervous tissue. The main functions of neurons are the generation, conduction and transmission of a nerve impulse - an electrical signal transmitted through nerve cells.
A neuron consists of a body and processes. The shoots are short and long. Long processes of nerve cells permeate the body and provide communication between the brain and spinal cord and any part of the body. In most neurons, the long process has a sheath of a special fat-like substance called myelin. The myelin sheath helps insulate the nerve fiber. A nerve impulse is carried through such a fiber faster than through one without myelin. Based on the presence or absence of a membrane, all processes are divided into myelinated and unmyelinated.
The myelin sheath is white, which makes it possible to divide the substance of the nervous system into white and gray. The cell bodies of neurons and their short processes form the gray matter of the brain, and the fibers form the white matter.
The functional difference in neuron processes is associated with the conduction of nerve impulses.
The process along which the impulse travels from the body of the neuron is called an axon. In most nerve cells, the axon is a long process.
The extension of a neuron along which the impulse travels to the cell body is called a dendrite. A neuron may have one or more dendrites. Dendrites, moving away from the cell body, gradually branch at an acute angle.
Synapses
Signal transmission from cell to cell occurs in special formations - synapses. This name was given to them in 1897 by Charles Sherrington. In them, the terminal branch of the axon is thickened and contains vesicles with an irritating substance - a mediator. When nerve impulses travel along the axon to the synapse, the vesicles burst and fluid containing mediators enters the synaptic cleft. Depending on its composition, a cell regulated by a neuron can start working, that is, get excited, or stop working (slow down).
Classification of neurons by function
Neurons vary according to its functions and are divided into sensory, intercalary and motor.
Sensory neurons- these are nerve cells that perceive stimuli from the external or internal environment of the body.
Motor(executive) neurons - neurons that innervate muscle fibers and glands.
Interneurons provide communication between sensory and motor neurons.
There can be a very large number of interneurons between the sensory and motor neurons. They collect and analyze information received from sensory neurons and make decisions on how to respond to changing conditions.
Classification of the nervous system by location
nervous system ( by location) are divided into central and peripheral. The central nervous system includes the spinal cord and brain, the peripheral nervous system includes nerves, nerve ganglia and nerve endings.
Nerves- bundles of long processes, covered with a common membrane, extending beyond the brain and spinal cord.
If information along a nerve comes from receptors in the brain or spinal cord, then such nerves are called sensory, centripetal or afferent. These nerves are composed of dendrites of sensory neurons.
If information along the nerve goes from the central nervous system to the executive organs (muscles or glands), then the nerve is called motor or efferent. Motor nerves are formed by the axons of motor neurons.
Mixed nerves contain both sensory and motor fibers.
Nerve nodes- These are clusters of neuron cell bodies outside the central nervous system.
Nerve endings- branches of neuron processes, used to receive or transmit signals.
Classification of the nervous system by function
Functions of the nervous system divided into somatic and vegetative (autonomous).
Somatic nervous system(from the Greek “soma” - “body”) regulates the work of skeletal muscles. Thanks to it, the body maintains contact with the external environment through the senses. With its help, we can arbitrarily (at our own request) control the activity of skeletal muscles.
The activity of internal organs, metabolic reactions, maintaining the constancy of the internal environment of the human body is controlled by autonomic or autonomic nervous system. Its name comes from the Greek word “autonomy” - self-government. The operation of this system is not subject to human will. It is impossible, for example, to speed up the digestion process or narrow blood vessels at will.
Autonomic nervous system
The autonomous system is represented by two departments- sympathetic and parasympathetic. Sympathetic department(system of complex situations) turns on during intense work that requires energy expenditure (heard something unexpected - the pupils dilate, the heart rate increases, the activity of the digestive system slows down, breathing quickens). Parasympathetic Division can be called a rebound system. It returns the body to a state of rest, creates conditions for rest and restoration of the body.
Reflexes
The basic principle of the nervous system is reflex. Any response of the body to a stimulus, carried out and controlled by the nervous system, is called reflex. The basis of the reflex reaction is the reflex arc. The reflex arc includes a receptor that perceives irritation. Along the axon of the sensory neuron, excitation enters the central nervous system and can spread directly to the motor neuron or first to the interneurons, and through them to the efferent neuron. Along the axon of the efferent neuron, excitation reaches the executive organ, most often a muscle. As a result of excitation, the activity of this organ changes, for example, the muscle contracts.
Reflexes are divided into somatic, ending with contraction of skeletal muscles, and autonomic, as a result of which the functioning of internal organs changes. An example of the simplest somatic reflex is the arc of the knee reflex, consisting of only two neurons - sensitive and motor.
1. Kolesov D.V., Mash R.D., Belyaev I.N. Biology 8 M.: Bustard
2. Pasechnik V.V., Kamensky A.A., Shvetsov G.G. / Ed. Pasechnik V.V. Biology 8 M.: Bustard.
3. Dragomilov A. G., Mash R. D. Biology 8 M.: VENTANA-GRAF
1. Kolesov D.V., Mash R.D., Belyaev I.N. Biology 8 M.: Bustard - p. 39, tasks and question 6,7,8,9.
2. What divisions of the nervous system are distinguished by location?
3. Describe the structure of a neuron.
4. Prepare an essay on diseases of the nervous system.
The importance of the nervous system in the human body is enormous. After all, it is responsible for the relationship between every organ, organ systems and the functioning of the human body. The activity of the nervous system is determined by the following:
- Establishing and establishing relationships between the outside world (social and ecological environment) and the body.
- Anatomical penetration into every organ and tissue.
- Coordinating every metabolic process occurring inside the body.
- Managing the activities of apparatuses and organ systems, combining them into one whole.
The importance of the human nervous system
In order to perceive internal and external stimuli, the nervous system has sensory structures located in the analyzers. These structures will include certain devices capable of receiving information:
- Proprioceptors. They collect all information regarding the condition of muscles, bones, fascia, joints, and the presence of fiber.
- Exteroceptors. They are located in human skin, sensory organs, and mucous membranes. Able to perceive irritating factors received from the surrounding environment.
- Interoreceptors. Located in tissues and internal organs. Responsible for the perception of biochemical changes received from the external environment.
Basic meaning and functions of the nervous system
It is important to note that with the help of the nervous system, perception and analysis of information about stimuli from the external world and internal organs is carried out. She is also responsible for responses to these irritations.
The human body, the subtlety of its adaptation to changes in the surrounding world, is accomplished primarily through the interaction of humoral and nervous mechanisms.
The main functions include:
- The definition and activities of man, which constitute the basis of his social life.
- Regulation of the normal functioning of organs, their systems, tissues.
- Integration of the body, its unification into a single whole.
- Maintaining the relationship of the whole organism with the environment. If environmental conditions change, the nervous system adapts to these conditions.
In order to accurately understand the importance of the nervous system, it is necessary to delve into the meaning and main functions of the central and peripheral nervous systems.
The importance of the central nervous system
It is the main part of the nervous system of both humans and animals. Its main function is the implementation of various levels of complexity of reactions called reflexes.
Thanks to the activity of the central nervous system, the brain is able to consciously reflect changes in the external conscious world. Its significance is that it regulates various kinds of reflexes and is able to perceive stimuli received both from internal organs and from the external world.
The importance of the peripheral nervous system
The PNS connects the central nervous system to the limbs and organs. Its neurons are located far beyond the central nervous system - the spinal cord and brain.
It is not protected by bones, which can lead to mechanical damage or harmful effects of toxins.
Thanks to the proper functioning of the PNS, the body's movements are coordinated. This system is responsible for conscious control of the actions of the entire organism. Responsible for responding to stressful situations and danger. Increases heart rate. In case of excitement, it increases the level of adrenaline.
It is important to remember that you should always take care of your health. After all, when a person leads a healthy lifestyle, adheres to the correct daily routine, he does not burden his body in any way and thereby remains healthy.
The endocrine and nervous systems ensure the regulation of vital processes in the body. The nervous system is complexly organized and highly specialized, the structural unit is the neuron. The nervous system connects all cells, tissues, and organs into a single whole. The activity of the nervous system is carried out by reflex.
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STRUCTURE AND IMPORTANCE OF THE NERVOUS SYSTEM. Biology teacher Kapitonova T.P.
Comparison of nervous and humoral regulation Feature Endocrine Nervous Mechanism of regulation Chemical substances entering the blood Nerve impulse through cells Reaction speed Slow, 0.5 m/s, partially destroyed along the way High speed, from 0.5 to 120 m/s Evolutionary age More ancient mechanism Young mechanism Economy of the process Does not provide an accurate and rapid response of the body to a stimulus; long-lasting response Minimal energy consumption, turns on and off instantly, short-term response
Classifications of the nervous system 1. By location: Central nervous system CNS - brain and spinal cord Peripheral nervous system - roots of spinal and cranial nerves, their branches, plexuses and nodes located in various parts of the human body.
2. Anatomical and functional classification A. somatic, which provides innervation to the body, namely the skin, skeletal muscles; B. vegetative, (autonomous) which innervates all the insides, glands, including endocrine, non-striated muscles of organs, skin, blood vessels, heart, and also regulates metabolic processes in all organs and tissues. The autonomic system is divided into parasympathetic and sympathetic. In each of these parts, as in the somatic nervous system, there are central and peripheral sections.
Reflex Unconditioned, congenital Conditioned, acquired
The structure of the reflex arc Receptor - perceives irritation and responds to it with excitement. Located in the skin and in all internal organs, clusters of receptors form sensory organs (eye, ear, etc.). Sensitive neuron (centripetal, afferent) transmitting excitation to the center. An interneuron in the central nervous system, a synaptic connection occurs between the sensory and motor neurons. Motor (centrifugal, efferent) neuron. Approaches the working organ and transmits a signal from the central nervous system to it. Effector - the working organ carries out a reaction in response to receptor stimulation
Test yourself 1. The basis of thinking and speech is the work of: A. Respiratory system B. Nervous system B. Circulatory system 2. The white matter of the brain is formed by: A. Axons B. Dendrites C. Neuron bodies 3. Impulses from the neuron body pass through: A. Axons B. Dendrites B. Receptor endings 4. The transformation of external stimuli into nerve impulses occurs in: A. Brain B. Receptors C. Spinal cord 5. Neurons that conduct impulses from the central nervous system to working organs are called: A. Sensitive B. Intercalary B. Motor 6. The accumulation of neuron bodies outside the central nervous system is called: A. Nerve ganglia B. Nerves C. Receptors 7. The part of the nervous system that innervates skeletal muscles and skin is called: A. Autonomous B. Somatic C. Central 8. The part of the nervous system that innervates internal organs are called: A. Vegetative B. Somatic C. Central
Answers. 1 – B 2 – A; 3 – A; 4 – B; 5 – B; 6 – A; 7 – B; 8 – A;
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Study § 7 of the textbook and fill out the diagrams.
Functions of the nervous system: ensures homeostasis, ensures communication with the external environment, coordinated work of organs and systems.
Nervous system (classification according to topographic principle): central $→$ brain, spinal cord; peripheral $→$ nerves, nerve endings, nerve ganglia.
Nervous system (anatomical and functional classification): somatic; autonomic $→$ sympathetic, parasympathetic.
2. Structure and types of neurons. Reflex and reflex arc
1 . Remember the structure of nervous tissue (§ 3 of the textbook). Look at the picture and label the names of the indicated parts of the neuron.
2 . Look at the drawing. Label the names of the parts of the synapse.
3 . Study the material in § 8 of the textbook on the classification of neurons and fill out the diagram.
Types of neurons $→$ sensitive $→$ conduction of an impulse in the ONS $←$ Functions of neurons;
Neuron types $→$ intercalary $→$ connect neurons $←$ Functions of neurons;
Neuron types $→$ motor $→$ from the ONS to the working body $←$ Functions of neurons.
4 . According to § 8 of the textbook, study the structure of the nerve. Label the names of its parts.
5 . Using the material from § 8 of the textbook, define the concepts.
Neuron is a nerve cell.
Spleen - place of functional contact of neurons.
Mediator - chemical mediators in the transmission of excitation.
Nerve - bundles of nerve fibers supplied with blood vessels and covered with a common membrane.
6 . Based on the material in the textbook (§8), study the structure of the reflex arc. List the main structures of the reflex arc indicated in the figure.
7 . Formulate definitions of concepts.
Reflex - the body's response to irritation from the external or internal environment.
Reflex arc - the basis of the reflex formed by neurons.
Nervous system
Vertically: 2. The body's response to irritation (reflex).
Horizontally: 1. Bundles of long processes of neurons (nerves). 2. Neurons that transmit impulses from the sensory organs to the central nervous system (sensitive). 4. Part of the nervous system, represented by nerves, nerve ganglia and nerve endings (peripheral). 5. Reflexes that are formed throughout life (conditioned). 6. Neurons that transmit impulses from the central nervous system to the working organ (motor). 7. Nerve cell process (axon). 8. Neurons that communicate between sensory and motor neurons (intercalary).
3. Structure and functions of the spinal cord
Study the material in § 9 of the textbook. Label the structures of the spinal cord indicated in the figure.
4. Structure and functions of the brain
1 . Using the material from § 10 of the textbook, define the concepts.
Brain stem - medulla oblongata, hindbrain, midbrain, diencephalon and reticular forms.
Cranial nerves - nerves that innervate the sensory organs, tissues, organs of the chest and abdominal cavities.
2 . Indicate which reflex centers are located in the medulla oblongata.
3 . Look at the drawing. Write the names of the main parts of the brain.
5. Organization and significance of the cerebral hemispheres
Fill the table.
Brain and spinal cord
Vertically: 2. Nervous system, represented by the brain and spinal cord (central).
Horizontally: 1. Specialized cells located in the sensory organs (receptors). 3. A section of the brain involved in coordinating movements, maintaining body posture and balance (cerebellum). 4. Root spine of the spinal nerve, consisting of motor fibers (anterior). 5. Lobe of the cerebral cortex (occipital). 6. Brain substance formed by clusters of neuron bodies (gray). 7. Section of the brain (thalamus). 8. Folds of the cerebral cortex (gyri). 9. Zone located in the occipital lobe of the cerebral hemispheres (visual). 10. The brain, located in the cranial cavity (head). 11. The portion of the cerebral cortex responsible for human behavior (frontal). 12. The portion of the cerebral cortex in which the olfactory zone is located (temporal).
6. General plan of the structure of the autonomic nervous system
1 . Study § 12 of the textbook and fill out the table.
Differences between the sympathetic and parasympathetic divisions of the autonomic nervous system
| Peculiarity | Autonomic Nervous System Division | |
| sympathetic | parasympathetic | |
| 1 | 2 | 3 |
| Where fibers exit the spinal cord | thoracic lumbar segment | middle, medulla, sacral spinal cord |
| Location of ganglia | on both sides of the spine | near and inside inert organs |
| Length of preganglionic and postganglionic nerve fibers | preganglionic are shorter than postganglionic | preganglionic ones are longer than postganglionic ones |
| Mediator | adrenalin | acetylcholine |
| Conditions | strengthening and accelerating organ function | slowing down the rhythm |
| General effects | activation of body systems in critical situations | control of “everyday” functions |
2 . Formulate definitions of concepts, write them down in your notebook and remember them.
Lesson 12. General outline of the structure of the nervous system and its functions. The structure of nervous tissue and its properties
19.01.2015 5066 738Lesson objectives:form concepts about the structure and functions of the nervous system, nervous tissue, neutrons; develop the ability to work with a textbook, draw up diagrams, and conduct self-observations.
Equipment:table “Structure of the nervous system”, “Structure of nervous tissue”.
I.Organizing time
II.Checking homework
1) Card No. 1
- The work of which regulatory systems maintains the relative constancy of the internal environment?
- What does this mean for the functioning of the body?
Card No. 2
- Explain why nervous regulation occurs faster than humoral regulation; what are the specific features: a) nervous; b) humoral regulation.
Card No. 3
- How is the activity of the human body regulated by the nervous and endocrine systems of organs?
Card No. 4
- Explain the meaning of the terms: homeostasis, homeostatic reactions, regulation, neurohumoral regulation, self-regulation.
2) Frontal work on homework. (Students use their own examples to show the effect of self-regulation processes; there is a discussion.)
III.Updating of reference knowledge
The table “Nervous System” is posted on the board.
Teachersuggests writing down all the associations that arise when these words are mentioned.
First, students work individually (1-2 minutes), then discuss in pairs, then in groups of four. Make a general list of associations and use them to compose a story about the nervous system.
During the conversation, it is emphasized that the nervous system is complexly organized and highly specialized, its main structural unit is the nerve cell
- neuron.The main property of nervous tissue is excitability, i.e., the ability to form an excitation process in response to irritation. Excitation underlies the mechanisms of the nervous system. The nervous system functionally connects all the cells, tissues and organs of the human body into a single whole; plays a leading role in the regulation of life, ensuring the interaction of the body with the environment.
Students define the nervous system and fill out the first block in the notebook in the diagram “Structure and functions of the nervous system”
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Table. Structure and functions of the nervous system
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IV.Learning a new topic
1) The teacher points out that in the topic “Nervous System” the answers to the following questions will be found:
- How is the coordination of the work of different bodies achieved?
- How does the structure of the nervous system provide the function of uniting organs to work together?
- How, for example, does the work of muscles coordinate with the activity of internal organs?
- What role do the sense organs and nervous system play in connecting the body with the external environment?
(You can give students the opportunity to formulate questions that interest them.)
2) At the next stage of the lesson, the Goals of the lesson are formulated, the solution of which will allow answering all the questions posed. Based on this, the names of the circuit blocks are indicated.
The importance of the nervous system
Independent work . A search conversation is organized, during which the importance of the nervous system in human life is clarified.
If a textbook is available, work is organized according to § 43 (Uch. K.; Uch. B., § 7; Uch. D. § 46).
Exercise. Read the text in the textbook, p. 220-221 (Uch. K.). Next to each paragraph, make a note in pencil:
“V” - familiar information;
« t " - new information;
“-” - thought differently;
"?" - unclear. If it is not clear, ask the teacher a question.
(After completing the work, erase the notes)
Determine the importance of the nervous system in a person’s life.
After discussion, the second block of the scheme is drawn up.
The material is reinforced by work on the questions after § 43.
The next stage of the lesson is an introduction to the basic terms of the topic.
Teacher's story using the table “Structure of nervous tissue”, fig. 8, .. 14 (Uch. B.), fig. 16, p. 38 (Uch. K.), fig. 10, p. 23 (Uch.D.). On the students’ desks is a short dictionary of terms on the topic “Nervous System” (see appendix).
L Nervous tissue. Nerve tissue consists of highly specialized nerve cells called neurons and cells neuroglia(fill the space between neurons and the capillaries surrounding them, participate in the metabolism of neurons).
/O Neuron- is the basic structural and functional unit of the nervous system
I smy. A neuron is a nerve cell with processes. It contains a cell body, one long, slightly branched process - the axon, and many (from 1 to 1000) short, highly branched processes - dendrites. The length of the axon reaches more than a meter, and the length of the dendrite can reach 300 microns. Neurons are very diverse in shape and number of processes.
> Cells that receive information have the longest axons in sensory organs and transmitting it to the central nervous system. The axon of such a neuron can extend from the cell body, located near the spinal cord, to a distance of about a meter, for example to a toe. The processes of neurons located entirely in the central nervous system are usually shorter.
The long shoots are often covered with a sheath of white fat-like substance - myelin sheath. Their accumulations in the central nervous system form white matter. Short processes and cell bodies of neurons do not have such a membrane. Their clusters form gray matter.
The body of a nerve cell is covered with a complex membrane and contains organelles characteristic of any other cell: the cytoplasm contains a nucleus with one or several nucleoli, mitochondria, ribosomes, Golgi apparatus, endoplasmic reticulum, etc.
A characteristic feature of the structure of a nerve cell is the presence of a large number of ribosomes. Ribosomes in nerve cells are associated with a high level of metabolism - protein synthesis.
Neurons are distinguished by structure and function. According to their functional properties, sensitive (or centripetal) neurons are distinguished, carrying excitation from receptors - nerve endings to the central nervous system, motor (or centrifugal) neurons, transmitting excitation from the central nervous system to the innervated organ, and intercalary, contact or intermediate neurons connecting between are sensory and motor pathways. The bodies and processes of these neurons do not extend beyond the central nervous system.
Clusters of nerve cell bodies outside the central nervous system resemble nerve nodes or ganglia.
l Neuroglia located between neurons and constitutes the intercellular substance of nervous tissue.
In the body, excitation is carried out through nerves, which include a large number of nerve fibers of different structure and function. Each bundle of nerve fibers is surrounded by a connective tissue sheath. The entire nerve is covered by a common sheath. Along each nerve fiber of the nerve, the impulse propagates in isolation without passing to other fibers. There are sensory (centripetal), motor (centrifugal) and mixed nerves. Typically, a nerve consists of 10 3 -10 4 fibers, but in humans there are over 1 million of them in the optic nerve. They are fed by blood vessels located in the nerve.
The cranial nerves come from the brain, and the spinal nerves come from the spinal cord.
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