5.4.1. Nervous system. General plan of the building. Functions.
5.4.2. Structure and functions of the central nervous system.
5.4.3. Structure and functions of the autonomic nervous system.
5.4.4. Endocrine system. Neurohumoral regulation of vital processes.
Nervous system
Multicellular organisms require a complex system for coordinating all life processes to maintain a constant internal environment and timely response to external influences. In the human body, this function is performed by the nervous, endocrine and immune systems.
Nervous regulation is a set of indicators in the human body that coordinate the work of individual organs and systems, interact with each other and the whole organism with the environment through the occurrence and transmission of electrical waves - nerve impulses.
Nervous regulation is ensured by the functioning nervous system. The activity of the nervous system is based on irritability and excitability.
The human nervous system is formed by nervous tissue, the structural unit of which is neuron. Under the influence of sufficiently strong stimuli, such as flashes of light, nerve impulses arise and are transmitted in neurons. Based on the nature of their activity, neurons are divided into sensory, intercalary and motor. Sensitive neurons conduct nerve impulses from organs to the central nervous system, motor- from the central nervous system to the organs, while any neurons lying between them are called intercalated.
The main form of activity of the nervous system is the reflex.
A reflex is the body’s reaction to any stimulus, which is carried out using the nervous system.
The path along which the nerve impulse passes during the implementation of the reflex is called reflex arc. An elementary reflex arc is formed by two neurons - sensory and motor. An example of such a reflex arc is the knee reflex arc (Fig. 5.43). If you apply a light blow below the knee with a special hammer, the shin and foot will be sharply thrown forward in response. Most reflex arcs in the human body contain all three types of neurons: sensory, intercalary and motor.
The reflex occurs only if all parts of the reflex arc are excited. If inhibition occurs in at least one of them, then the reflex will not appear.
Anatomically, the nervous system is divided into central(CNS) and peripheral(PNS). The central nervous system, in turn, is divided into the brain and spinal cord, and the PNS is a collection of nerves and nerve ganglia, lying outside the central nervous system. Depending on the functions performed, they are distinguished somatic And autonomous (vegetative) nervous systems. The somatic nervous system, which is a collection of nerve centers and nerves, controls the work of the body’s muscles, and the autonomic (autonomic) nervous system controls the work of internal organs.
The spinal cord is located in the spinal canal formed by the vertebral bodies and arches. On the outside, it is covered with three shells: hard, arachnoid and soft. The spinal cord looks like a long cord, divided by longitudinal grooves into right and left halves.
At the center of the spinal cord there is a spinal canal filled with cerebrospinal fluid. The spinal canal is surrounded by gray matter, while at the periphery of the spinal cord there is white matter (Fig. 5.44). The white matter is formed by long processes of neurons that form pathways. Gray matter consists of the cell bodies of motor neurons and interneurons. 31-33 pairs of spinal nerves depart from the spinal cord, innervating the organs of the body. Spinal nerves are formed by the fusion of the anterior (motor) and posterior (sensory) roots.
The spinal cord performs conductor and reflex functions. It contains the centers of such reflexes as the knee and urination. However, the work of the spinal cord is carried out under the control of the brain, therefore, while concentrating, we may not respond to the tapping of a neurological hammer under the knee.
When the spinal cord is damaged, its conductivity is disrupted: below the site of injury, the sensitivity of parts of the body and the ability to move are lost.
The human brain is located in the cranial cavity and has the same three membranes as the spinal cord - hard, arachnoid and soft (Fig. 5.45). Outside and inside, in the ventricles, the brain is washed by a special liquid - cerebrospinal fluid. The average weight of the brain is about 1300-1400 g, but the brain of I. S. Turgenev weighed more than 2 kg, and the brain of A. France - just over 1 kg, and this did not prevent them from becoming classics of world literature.
The brain is anatomically divided into the medulla oblongata, pons, cerebellum, midbrain, diencephalon and forebrain.
IN medulla oblongata there are the centers of breathing, heartbeat, chewing, swallowing, sweating, protective reflexes (coughing, sneezing, vomiting, lacrimation and blinking), postural maintenance reflexes, etc. In addition to the reflex function, it also performs a conductive function, since nerve tracts from the spinal cord pass through it brain into the bridge.
Bridge, in turn, connects the midbrain and medulla oblongata, and mainly performs a conductive function.
Cerebellum formed by two hemispheres covered with cortex. It coordinates the movements of the body, participates in maintaining muscle tone and regulating the functioning of internal organs.
IN midbrain there are centers for the primary analysis of information coming from the senses, as well as pathways. In response to a flash of light or a strong sound, a person turns his head in the direction of the stimulus - this is an unconditioned orienting reflex. The midbrain plays an important role in regulating skeletal muscle tone.
Diencephalon formed by the thalamus (visual thalamus) and hypothalamus (subthalamus). The thalamus contains centers for analyzing visual information, as well as organizing instincts, drives and emotions. It integrates nerve pathways to and from the forebrain, and also quickly analyzes and switches information from various organs of the body to different parts of the forebrain cortex. The diencephalon also includes the hypothalamus, which is the highest center of neurohumoral regulation in the human body, and the pineal gland - pineal gland related to the endocrine system. In the lower part, the hypothalamus is connected to the pituitary gland - an endocrine gland. The functions of the hypothalamus are the regulation of metabolism, thermoregulation, the activity of the digestive, endocrine and excretory systems, the circulatory system, hunger and satiety, thirst and its quenching, fear, rage, sleep and wakefulness, as well as emotions.
In general, the diencephalon, together with the middle brain, carries out complex reflex or instinctive reactions. Some of its centers take part in maintaining attention without letting it pass into the cortex cerebral hemispheres currently unnecessary precentral signals. Anteriorly, it passes into the cerebral hemispheres of the telencephalon.
The medulla oblongata, pons, midbrain, diencephalon, and cerebellum are combined into brain stem. It performs reflex, conductive and associative functions, ensuring the interaction of all structures of the central nervous system. In the thickness of the gray matter of the medulla oblongata, pons, midbrain and diencephalon is located reticular formation- a network of neurons closely connected with other structures of the central nervous system. Its main function is to regulate the level of activity of the cerebral cortex, cerebellum, thalamus and spinal cord.
Greater forebrain hemispheres occupy most of the cerebral part of the skull, which is associated with the development of the functions of this part of the brain. They are covered with a cortex of gray matter, under which there is a subcortex - white matter. The gray matter of the cerebral cortex mainly consists of neuron bodies and their short processes, while the subcortex is a collection of their long processes, among which there are small clusters of neurons - subcortical centers or nuclei.
The cerebral cortex forms numerous grooves and convolutions, increasing its surface area. The largest grooves divide the cortex into lobes: frontal, temporal, parietal and occipital (Fig. 5.46). The areas of the cortex responsible for performing certain functions are called zones, or centers. There are no clear boundaries between them, but in total there are from 50 to 200 such centers. They can be divided into three groups: sensory, motor and associative. Sensory zones perceive signals from various receptors, in motor zones signals are formed to the corresponding organs, while associative zones combine the activities of the first two.
In the frontal lobe there are motor centers, in the parietal lobe there are olfactory and gustatory centers, as well as centers of the musculocutaneous sense, in the temporal lobe there are auditory centers, and in the occipital lobe there are visual centers.
The activities of associative zones are most strongly associated with higher mental functions - thinking and consciousness, speech, etc.
The subcortex contains the centers of ancient reflexes, such as blinking. Thus, the forebrain mainly performs a reflex function and is also the basis of human mental activity.
In the past, it was believed that left-handers were right-brain dominant, and right-handers were left-brain dominant. However, no anatomical differences were found between them. Subsequently, it was found that the centers of speech, writing, perception of numbers and notes, counting, etc. are located in the left hemisphere, while the perception of spatial images is carried out in the right hemisphere. Thus, the asymmetry of the hemispheres is functional in nature. At the same time, there are such close connections between the hemispheres that neither information processing nor most higher mental functions can be carried out by only one of them.
The autonomic nervous system, covering parts of the brain and nerves with their branches, innervates mainly internal organs - the heart, blood vessels, endocrine glands, etc. It is divided into two sections - sympathetic and parasympathetic.
Nodes sympathetic departments lie in the thoracic and lumbar regions of the spinal cord, as well as on both sides of the spinal column. The sympathetic division of the autonomic nervous system is responsible for mobilizing the body's reserves in response to strong stimuli. At the same time, the frequency and strength of heart contractions and respiratory movements increase, many blood vessels constrict, pupils dilate, the concentration of sugar in the blood increases, but at the same time, the processes of digestion and excretion are weakened.
Nodes parasympathetic departments are located in the medulla oblongata, the sacral part of the spinal cord and in the internal organs. The parasympathetic department normalizes the vital functions of the body, while the frequency and strength of heart contractions and respiratory movements decreases, blood vessels dilate, pupils constrict, the concentration of sugar in the blood decreases, but digestion and excretion increase.
A number of internal organs are innervated simultaneously by both parts of the autonomic nervous system, but only sympathetic or parasympathetic fibers are suitable for many blood vessels, the spleen, sensory organs and the central nervous system.
Endocrine system
Humoral regulation- This is the coordination of physiological functions with the help of biologically active substances through body fluids - blood, lymph and tissue fluid.
Biologically active substances are substances produced by the cells and tissues of the body and which have a strong stimulating effect on the functions of the body. These include hormones, vitamins and enzymes. Vitamins mostly enter the human body from the outside, while hormones and enzymes are produced by special glands.
The glands of the human body are divided into glands of external, internal and mixed secretion. TO exocrine glands These include all glands that have ducts and periodically discharge their products into the organ cavity or out. These are salivary, lacrimal, sweat, sebaceous and other glands. They produce digestive enzymes, tear fluid, sebum, etc. Endocrine glands produce hormones that enter the internal environment of the body. Glands of mixed secretion release their products into the blood and organs of the body.
Hormones- biologically active substances formed by specialized glands and exerting an effect in target tissues in microscopic quantities.
However, the influence of hormones does not extend to the entire body, but only to specific cells, tissues and organs. This property is called specificity. The lack of hormones associated with the hypofunction of the corresponding gland, as well as the excess due to its hyperfunction, negatively affect the functioning of the body, leading to the appearance of pathological changes.
The collection of endocrine glands is called endocrine system body. The structure and functions of the endocrine glands are studied by science endocrinology.
The endocrine system of the human body is formed by the hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid glands, pancreas, adrenal glands and gonads (ovaries and testes) (Fig. 5.47).
Hypothalamus- a section of the diencephalon, the highest center of neurohumoral regulation in the human body. It produces substances that influence the formation of pituitary hormones, as well as two hormones only released by the pituitary gland - vasopressin (antidiuretic hormone) and oxytocin. Vasopressin retains water in the body during urine formation. A decrease in the concentration of this hormone leads to rapid loss of water and even dehydration. Oxytocin stimulates labor, causing the fetus to be expelled from the uterus.
Pituitary- a small gland that is located at the base of the brain and produces a number of hormones, and also releases vasopressin and oxytocin produced by the hypothalamus. Pituitary hormones stimulate the activity of other endocrine glands. These include adrenocorticotropic
hormone (ACTH), gonadotropic hormones - luteinizing hormone (LH) and follicle-stimulating hormone (FSH), lactotropic hormone, or prolactin (LTH), melanocyte-stimulating hormone (MSH), eomatotropic hormone (STG) and thyroid-stimulating hormones (TSH).
ACTH regulates the activity of the adrenal glands and stimulates the release of adrenaline. Gonadotropic hormones contribute to the formation of the gonads and their normal functioning. LTG causes the mammary glands to enlarge and produce milk in the mother after the baby is born. MSH enhances human skin pigmentation. HGH stimulates body growth. Lack of growth hormone leads to dwarfism, while body proportions and mental development remain normal. Excess growth hormone causes gigantism, and if the concentration of the hormone increases in an adult, then the size of individual protruding organs increases - this disease is called acromegaly. TSH controls the activity of the thyroid gland.
Epiphysis, or pineal gland, part of the diencephalon, participates in the regulation of the body’s biological rhythms and produces hormones melatonin, causing skin lightening.
Thyroid, located in the middle region of the neck, secretes the thyroid hormones thyroxine and triiodothyronine, as well as calcitonin. Thyroid hormones regulate metabolism in the body, promoting normal processes of growth, development and differentiation of tissues. Calcitonin reduces calcium levels in the blood by depositing it in the bones.
Hyperfunction of the thyroid gland leads to an increase in metabolic rate, excitability of the nervous system, insomnia and the development of goiter. The complex of these symptoms is called Graves' disease. Hypofunction of the thyroid gland, on the contrary, causes a slowdown in metabolism that accumulates in the skin and increases the excitability of the nervous system. This disease is called myxedema. Lack of thyroid hormones in childhood and adolescence leads to dwarfism and cretinism.
Parathyroid glands located on the surface of the thyroid gland and secrete parathyroid hormone. It helps increase calcium levels in the blood and is therefore a calcitonin antagonist. Overfunction of the parathyroid glands can lead to bone disorders and osteoporosis.
Adrenal glands- paired endocrine organs lying near the upper part of the kidneys. The adrenal glands are divided into a cortex and a medulla. Corticosteroids are produced in the adrenal cortex, and adrenaline and norepinephrine are produced in the medulla. Corticosteroids regulate the metabolism of organic and inorganic substances in the human body. Their deficiency leads to Addison's (bronze) disease, symptoms of which are increased skin pigmentation, weakness, dizziness, arterial hypotension, vague pain in the intestinal area and diarrhea.
Adrenaline is secreted by the adrenal glands in many critical situations. It enhances the work of the heart, constricts blood vessels, inhibits digestion, increases oxygen consumption, increases the concentration of glucose in the blood, blood flow in the liver, etc. The release of adrenaline into the blood is associated with the effect of strong irritants on the human body and is an integral component of the body's stress reactions.
To the glands mixed secretion include the pancreas and gonads.
Pancreas, in addition to digestive enzymes, it releases the hormones insulin and glucagon into the bloodstream, which regulate carbohydrate metabolism. Insulin reduces the concentration of glucose in the blood, promoting its binding in the liver and other organs, and glucagon, on the contrary, it increases the concentration of glucose in the blood due to the breakdown of glycogen in the liver. Lack of insulin, leading to an increase in blood glucose concentrations, causes the development of diabetes mellitus Excess insulin can lead to a sharp drop in glucose concentration, loss of consciousness and seizures. Deviations in glucagon levels in humans are extremely rare.
Sex glands produce simultaneously reproductive products and sex hormones (female - estrogens, men's - androgens), having a significant impact on the processes of growth, development and puberty, as well as regulating the formation of secondary sexual characteristics.
Neurohumoral regulation of the body’s vital processes as the basis of its integrity and connection with the environment
The nervous and endocrine systems are an inextricable unity, determined by numerous direct and feedback connections. Receiving signals from various receptors is the prerogative of the nervous system, which is the first to be involved in its work. Its impulses instantly and accurately affect organs, changing their activity. However, control by the nervous system is short-lived; it acts in a targeted manner, while in order to “consolidate” the effect and involve the whole organism in the reaction, a signal is sent through the hypothalamus to the endocrine system. The hypothalamus itself secretes the hormones vasopressin and oxytocin, which have a significant effect on body functions. The hypothalamus secretes neurohormones that regulate the functioning of the pituitary gland, which, in turn, influences other endocrine glands using its own hormones. Hormones secreted by the endocrine glands, on the one hand, act for a longer time, and on the other hand, they involve other organs in their work, and also coordinate their activities.
Hormones of the endocrine glands are also necessary for the normal development of the nervous system itself, since, for example, with a lack of thyroid hormones in childhood, underdevelopment of the brain occurs, leading to cretinism.
Detailed solution to § 6 in biology for 8th grade students, authors V. V. Pasechnik, A. A. Kamensky, G. G. Shvetsov 2016
- Gdz workbook in Biology for 8th grade can be found
REMEMBER
Question 1. What properties of living things do you know?
Living matter is characterized by the following properties:
Metabolism
Self-regulation
Development and variability
Ability to reproduce
Heredity
Irritability
Question 2. What types of regulation of vital processes in animals do you know?
There are nervous and humoral regulation of vital processes in animals.
QUESTIONS FOR THE PARAGRAPH
Question 1. Describe the manifestation of the basic vital properties of a person at the cellular and organismal level.
Structural elements cellular level are the structural parts of the cell - molecules and their complexes that create the surface apparatus, nucleus and cytoplasm with organelles. The interaction between them ensures the integrity of the cell in the manifestation of its properties as a living system in relations with the external environment.
The basic processes of the cellular level, inherent only to this level of organization of life, arose during the evolution of living matter: metabolism (metabolism); absorption and therefore inclusion of various chemical elements Earth into the contents of a living organism; transfer of hereditary information from cell to cell; accumulation of changes in genetic apparatus as a reflection of the experience of interaction with the environment; response to stimuli during this interaction.
Question 2. What is homeostasis and what underlies it?
The most important property of any living system is self-regulation. A person has a manifestation of this property is expressed in the activity of all structures of the body, aimed at maintaining the relative constancy of their composition, structure and functioning - homeostasis. The coordinated work of the functional systems of the human body in the real changing conditions of his life is aimed at maintaining homeostasis.
Question 3. What is the neurohumoral regulation of human life processes expressed in?
The coordinated work of the body is controlled by the nervous system and the endocrine glands (humoral). They work as a single whole - the neurohumoral regulatory system. Nervous regulation occurs very quickly: to the organ nerve cells electrical signals called nerve impulses arrive. It is these nerve impulses that either enhance the functioning of the organ or inhibit it. Electrical signals travel along the nerves at enormous speed (up to 100 m/s), but act only at the moment they approach the organ, that is, their effects are short-term.
Humoral regulation occurs with the help of special substances - hormones, most often secreted by special glands. These substances are carried by the blood throughout the body and are capable of interacting with the cells of various organs and regulating their functioning. Of course, the production of these substances and their transfer through the bloodstream takes more time than the propagation of nerve impulses, so humoral regulation is slower than nervous regulation. But the impact of these substances on the functioning of organs and tissues is longer.
Question 4. What is a reflex? Give examples of reflexes in humans.
A reflex is the body’s response to any influence, occurring with the participation of the nervous system. An example would be pulling your hand away from a hot object. The path along which the reflex occurs is called a reflex arc. It is a sequentially connected chain of nerve cells - neurons: sensory, intercalary and motor. For a reflex to occur, the integrity of the reflex arc is necessary. Turning off its link leads to the disappearance of the reflex.
Examples of reflexes include the brow and knee reflexes.
1. Based on the analysis of the material in the paragraph and the results of self-observation of food, draw a conclusion about the difference between nervous and humoral regulation.
The two systems - nervous and humoral - differ in the following properties.
First, neural regulation is goal-directed. The signal along the nerve fiber comes to a strictly defined place, to a specific muscle, or to another nerve center, or to a gland. The humoral signal travels through the bloodstream throughout the body.
Secondly, the nerve signal is fast, it moves to another organ, i.e., to another nerve cell, muscle cell or gland cell at a speed of 7 to 140 m/s, delaying switching at synapses for only one millisecond. Thanks to neural regulation, we can do something “in the blink of an eye.” The content of most hormones in the blood increases only a few minutes after stimulation, and can reach a maximum only after tens of minutes. As a result, the greatest effect of the hormone can be observed several hours after a single exposure to the body. Thus, the humoral signal is slow.
Third, the nerve signal is brief. Typically, the burst of impulses caused by a stimulus lasts no more than a fraction of a second. This is the so-called switching reaction.
The main differences between nervous regulation and humoral regulation are as follows: the nerve signal is purposeful; the nerve signal is fast; the nervous signal is brief.
2. Prepare a message about human reflexes.
HUMAN REFLEXES
Reflexes play a big role in the life of any creature. Their enormous importance is no coincidence, because it is the nervous system that plays the leading role in the perception of the surrounding world. With its help, an individual can both admire and protect himself from the external environment. Human reflexes become indispensable precisely for the implementation of such protection. As an example, consider withdrawing your hand from hot surfaces.
The reflex is the body's main reaction to environment. Its implementation is impossible without the participation of the nervous system. Thus, a behavioral reaction occurs in response to any type of stimulus that affects the nerve endings.
The path along which impulses from irritation pass and the response to it is called a reflex arc. The simplest such formation should consist of at least two such paths. One of them is sensitive, and the second is motor. Thus, the hand is pulled away from the hot object: first the stimulus is felt, and then the movement occurs. These morphological interconnected formations ensure the perception, transmission and processing of signals by the body.
Any effect on the body will be carefully analyzed by the latter and transformed into a nerve impulse. After this, it will be sent to the central nervous system and transmit the necessary information about all changes to the entire body. It is worth noting that this entire complex process takes only a fraction of a second.
Thanks to reflexes, any organism is accurately oriented in time and space, finds food and avoids danger.
Thus, the meaning of the reflex comes down to ensuring the following tasks:
1. Interaction of all internal organs and systems as a whole;
2. Coordinated work of organs of different functions;
3. Ensuring the body’s response to the action of the external environment;
4. Functioning of the cerebral cortex.
There are so many reactions of the body that it became necessary to classify them. Let's consider what reflexes a person has.
First of all, they can be divided according to their importance for the conservation of a biological species into:
1. Defensive;
2. Sexual;
3. Indicative.
Also, reflexes can enhance or, conversely, inhibit the activity of the effector. As a shining example It can be mentioned that the sympathetic nervous system increases the heart rate, and the vagus nerve slows it down.
Any living organism reacts to stimuli in many ways. In this regard, in science there is a need to identify the types of human reflexes. Basically, it is customary to divide them into two large groups according to the type of education: conditional and unconditional.
Unconditioned reflexes are inherent in all living organisms from birth, that is, they do not need to be studied or made efforts to apply. Most often, when an unconditioned reflex is triggered, it seems that the action happened by itself. As an example of such reactions, we can highlight sucking, protective, sexual and other reflexes. Their goal is to ensure the survival of the organism for procreation and adapt to environmental conditions.
The appearance of such stereotypical reactions is associated with the evolutionary development of species of living beings. The body's reaction with an unconditional response is carried out at the level of the spinal and lower structures of the brain.
Usually unconditioned reflexes are so stable that they do not change or disappear in a person throughout his life. In addition, they are specific to one biological species.
Conditioned reflexes are developed by a living organism over a period of time. In other words, it is an adaptive behavior to adapt to repeated exposure to a stimulus. Naturally, this type of reflex reaction will be absent in a newborn.
Also, conditioned reflexes can fade away if they are not reinforced by the action of a stimulus for some time. The following types of conditioned reflex reactions are distinguished:
Natural. They are produced in response to stimuli on the basis of an unconditioned reflex. Thus, a person knows what a particular product smells like. Even if the food has no smell, the reflex will create a false sensation of it;
Artificial. A type of conditioned reflex, which consists of a response to a stimulus that is normal conditions does not combine with the unconditioned reflex.
Exteroceptive. Provide adaptation of the body to stimuli from the external environment;
Interoceptive. Provide adaptation to chemical and physical stimuli to ensure the functioning of internal organs.
In order to form a conditioned reflex response, you need to go through several steps:
1. The presence of two types of stimuli and the appearance of the conditional before the unconditional;
2. Repeated alternation of stimuli with each other;
3. At the same time, the unconditional stimulus must always remain stronger;
4. At the moment of developing a new reaction of the body, there should be no external stimuli;
5. All this is realized provided that the nervous system has no pathologies and functions normally.
THINK!
Why cannot types of regulation be opposed to each other?
Humoral regulation is closely related to nervous regulation and together with it forms a single neurohumoral mechanism of regulatory adaptations of the body. Nervous and humoral factors are so closely intertwined with each other that any opposition between them is unacceptable, just as the division of the processes of regulation and coordination of functions in the body into autonomous, ionic, vegetative, and animal components is unacceptable. All these types of regulation are so closely related to each other that a violation of one of them, as a rule, disorganizes the others.
Complex structure human body is currently the pinnacle of evolutionary transformations. Such a system requires special methods of coordination. Humoral regulation is carried out with the help of hormones. But the nervous system represents the coordination of activities using the organ system of the same name.
What is regulation of body functions
The human body has very complex structure. From cells to organ systems, it is an interconnected system, for the normal functioning of which a clear regulatory mechanism must be created. It is carried out in two ways. The first method is the fastest. It's called neural regulation. This process is implemented by the system of the same name. There is a misconception that humoral regulation is carried out with the help of nerve impulses. However, this is not at all true. Humoral regulation is carried out with the help of hormones that enter the body fluids.
Features of nervous regulation
This system includes a central and peripheral section. If the humoral regulation of body functions is carried out with the help of chemical substances, That this method represents a “transport highway” that connects the body into a single whole. This process happens quite quickly. Just imagine that you touched a hot iron with your hand or stepped out into the snow barefoot in winter. The body's reaction will be almost instantaneous. This is of utmost protective importance and promotes both adaptation and survival in various conditions. The nervous system underlies the innate and acquired reactions of the body. The first are unconditioned reflexes. These include breathing, sucking, and blinking. And over time, a person develops acquired reactions. These are unconditioned reflexes.
Features of humoral regulation
Humoral is carried out with the help of specialized organs. They are called glands and are combined into a separate system called the endocrine system. These organs are formed by a special type epithelial tissue and are capable of regeneration. The effect of hormones is long-term and continues throughout a person’s life.
What are hormones
The glands secrete hormones. Due to their special structure, these substances accelerate or normalize various physiological processes in the body. For example, at the base of the brain is the pituitary gland. It produces as a result of which the human body increases in size for more than twenty years.
Glands: features of structure and functioning
So, humoral regulation in the body is carried out with the help of special organs - glands. They ensure the constancy of the internal environment, or homeostasis. Their action is in the nature of feedback. For example, such an important indicator for the body as blood sugar level is regulated by the hormone insulin at the upper limit and glucagon at the lower limit. This is the mechanism of action of the endocrine system.
Exocrine glands
Humoral regulation is carried out with the help of glands. However, depending on the structural features, these organs are combined into three groups: external (exocrine), internal (endocrine) and mixed secretion. Examples of the first group are salivary, sebaceous and lacrimal. They are characterized by the presence of their own excretory ducts. Exocrine glands are secreted on the surface of the skin or in the body cavity.
Endocrine glands
Endocrine glands secrete hormones into the blood. They do not have their own excretory ducts, so humoral regulation is carried out using body fluids. Once in the blood or lymph, they spread throughout the body, reaching every cell. And the result of this is the acceleration or slowdown of various processes. This may be growth, sexual and psychological development, metabolism, the activity of individual organs and their systems.
Hypo- and hyperfunctions of the endocrine glands
The activity of each endocrine gland has “two sides of the coin.” Let's look at this with specific examples. If the pituitary gland secretes an excess amount of growth hormone, gigantism develops, and if there is a deficiency of this substance, dwarfism occurs. Both are deviations from normal development.
The thyroid gland secretes several hormones at once. These are thyroxine, calcitonin and triiodothyronine. If their quantity is insufficient, infants develop cretinism, which manifests itself in a lag in mental development. If hypofunction manifests itself in adulthood, it is accompanied by swelling of the mucous membrane and subcutaneous tissue, hair loss and drowsiness. If the amount of hormones in this gland exceeds the normal limit, a person may develop Graves' disease. It manifests itself in increased excitability of the nervous system, trembling of the limbs, and causeless anxiety. All this inevitably leads to emaciation and loss of vitality.
The endocrine glands also include the parathyroid, thymus and adrenal glands. The latter glands secrete the hormone adrenaline during a stressful situation. Its presence in the blood ensures the mobilization of all vital forces and the ability to adapt and survive in non-standard conditions for the body. First of all, this is expressed in providing the muscular system with the necessary amount of energy. The reverse-acting hormone, which is also secreted by the adrenal glands, is called norepinephrine. It is also of utmost importance for the body, since it protects it from excessive excitability, loss of strength, energy, and rapid wear and tear. This is another example of the reverse action of the human endocrine system.
Glands of mixed secretion
These include the pancreas and gonads. The principle of their operation is twofold. two types at once and glucagon. They, accordingly, lower and increase blood glucose levels. In a healthy human body, this regulation goes unnoticed. However, when this function is disrupted, a serious disease occurs, which is called diabetes mellitus. People with this diagnosis need artificial insulin administration. As an exocrine gland, the pancreas secretes digestive juice. This substance is secreted into the first section of the small intestine - the duodenum. Under its influence, the process of splitting complex biopolymers into simple ones occurs there. It is in this section that proteins and lipids are broken down into their component parts.
The gonads also secrete various hormones. These are male testosterone and female estrogen. These substances begin to act as early as during embryonic development, sex hormones influence the formation of sex, and then form certain sexual characteristics. As exocrine glands, they form gametes. Man, like all mammals, is a dioecious organism. Its reproductive system has a general structural plan and is represented by the gonads, their ducts and the cells themselves. In women, these are paired ovaries with their ducts and eggs. In men, the reproductive system consists of testes, excretory ducts and sperm cells. In this case, these glands act as exocrine glands.
Nervous and humoral regulation are closely interconnected. They work as a single mechanism. Humoral is more ancient in origin, has a long-term effect and affects the entire body, since hormones are carried by the blood and reach every cell. And the nervous system works pointwise, at a specific time and in a certain place, according to the “here and now” principle. Once the conditions change, it will cease to apply.
So, the humoral regulation of physiological processes is carried out using the endocrine system. These organs are capable of releasing special biologically active substances called hormones into liquid environments.
Video tutorial 2: Endocrine (humoral) regulation of the body. Glands
Lecture: Nervous and endocrine systems. Neurohumoral regulation of vital processes of the body
Nervous system
The human nervous system is the most highly organized in living nature. It connects together motor activity, the work of the senses and other systems that regulate the activity of the body.
It is divided into:
Central , the components of which are the brain and spinal cord;
Peripheral, which are nerve fibers. In this case, the peripheral one in turn is divided into:
Somatic, under the control of consciousness;
Vegetative – divided into sympathetic and parasympathetic. It includes nerves that arise from the spinal cord and innervate internal organs. At the same time, the sympathetic causes organs to be excited, providing a response to stress - it is responsible for accelerating the heartbeat, increasing blood pressure and other reactions. Parasympathetic - relaxes the organs, providing comfort during rest - contraction of the pupil, dilation of blood vessels.
The main properties of the nervous system are the ability to excite and conduct electromagnetic impulses. The basis of its work are reflexes.
This is a complex mechanism that is implemented using a reflex arc consisting of several links:
sensory neurons . A person feels touch on his skin;
centripetal neurons . The touch signal carried by the axon entered the brain;
association neurons . The signal was recognized, processed by the brain based on existing experience, then the brain generated a response signal;
centrifugal neurons . The electromagnetic signal went to the skeletal muscles;
effector. Obeying the order of the brain, the muscles contracted, the body made a movement, the man turned around to see who touched his skin.
In addition to muscles, glands or internal organs can also be effectors.
Endocrine system
The endocrine system provides humoral regulation, which is carried out through hormones. It acts in association with the nervous and immune systems. Its components are all the endocrine glands of the body.
These include:
thyroid – located on the anterior wall of the larynx, produces the growth hormone thyroxine;
pancreas– produces insulin, regulates blood glucose levels;
adrenal glands– secrete cortisol, necessary for protein metabolism, adrenaline – a stress hormone;
Nervous regulation carried out using electrical impulses traveling along nerve cells. Compared to humoral it
- happens faster
- more accurate
- requires a lot of energy
- more evolutionarily young.
Humoral regulation vital processes (from the Latin word humor - “liquid”) are carried out due to substances released into the internal environment of the body (lymph, blood, tissue fluid).
Humoral regulation can be carried out with the help of:
- hormones- biologically active (acting in a very small concentration) substances released into the blood by the endocrine glands;
- other substances. For example, carbon dioxide
- causes local expansion of capillaries, more blood flows to this place;
- stimulates the respiratory center of the medulla oblongata, breathing intensifies.
All glands of the body are divided into 3 groups
1) Endocrine glands ( endocrine) do not have excretory ducts and secrete their secretions directly into the blood. The secretions of the endocrine glands are called hormones, they have biological activity (act in microscopic concentration). For example: .
2) Exocrine glands have excretory ducts and secrete their secretions NOT into the blood, but into some cavity or onto the surface of the body. For example, liver, tearful, salivary, sweaty.
3) Mixed secretion glands carry out both internal and external secretion. For example
- the gland secretes insulin and glucagon into the blood, and not into the blood (into the duodenum) - pancreatic juice;
- sexual The glands secrete sex hormones into the blood, but not into the blood - sex cells.
Establish a correspondence between the organ (organ department) involved in the regulation of the vital functions of the human body and the system to which it belongs: 1) nervous, 2) endocrine.
A) bridge
B) pituitary gland
B) pancreas
D) spinal cord
D) cerebellum
Answer
Establish the sequence in which the humoral regulation of respiration occurs during muscular work in the human body
1) accumulation carbon dioxide in tissues and blood
2) stimulation of the respiratory center in the medulla oblongata
3) transmission of impulse to the intercostal muscles and diaphragm
4) gain oxidative processes during active muscle work
5) inhalation and air entering the lungs
Answer
Establish a correspondence between the process that occurs during human breathing and the method of its regulation: 1) humoral, 2) nervous
A) stimulation of nasopharyngeal receptors by dust particles
B) slowing down breathing when immersed in cold water
C) change in breathing rhythm with excess carbon dioxide in the room
D) difficulty breathing when coughing
D) a change in breathing rhythm when the carbon dioxide content in the blood decreases
Answer
1. Establish a correspondence between the characteristics of the gland and the type to which it is classified: 1) internal secretion, 2) external secretion. Write numbers 1 and 2 in the correct order.
A) have excretory ducts
B) produce hormones
C) provide regulation of all vital functions of the body
D) secrete enzymes into the stomach cavity
D) excretory ducts exit to the surface of the body
E) produced substances are released into the blood
Answer
2. Establish a correspondence between the characteristics of the glands and their type: 1) external secretion, 2) internal secretion. Write numbers 1 and 2 in the correct order.
A) form digestive enzymes
B) secrete secretions into the body cavity
C) release chemically active substances - hormones
D) participate in the regulation of vital processes of the body
D) have excretory ducts
Answer
Establish a correspondence between the glands and their types: 1) external secretion, 2) internal secretion. Write numbers 1 and 2 in the correct order.
A) pineal gland
B) pituitary gland
B) adrenal gland
D) salivary
D) liver
E) pancreatic cells that produce trypsin
Answer
Establish a correspondence between the example of regulation of the heart and the type of regulation: 1) humoral, 2) nervous
A) increased heart rate under the influence of adrenaline
B) changes in heart function under the influence of potassium ions
B) change in heart rate under the influence of the autonomic system
D) weakening of heart activity under the influence of the parasympathetic system
Answer
Establish a correspondence between the gland in the human body and its type: 1) internal secretion, 2) external secretion
A) dairy
B) thyroid
B) liver
D) sweat
D) pituitary gland
E) adrenal glands
Answer
1. Establish a correspondence between the sign of regulation of functions in the human body and its type: 1) nervous, 2) humoral. Write numbers 1 and 2 in the correct order.
A) delivered to organs by blood
B) high response speed
B) is more ancient
D) is carried out with the help of hormones
D) is associated with the activity of the endocrine system
Answer
2. Establish a correspondence between the characteristics and types of regulation of body functions: 1) nervous, 2) humoral. Write numbers 1 and 2 in the order corresponding to the letters.
A) turns on slowly and lasts a long time
B) the signal propagates through the structures of the reflex arc
B) is carried out by the action of a hormone
D) the signal travels through the bloodstream
D) turns on quickly and has a short duration
E) evolutionarily more ancient regulation
Answer
Choose one, the most correct option. Which of the following glands secrete their products through special ducts into the cavities of the body organs and directly into the blood?
1) greasy
2) sweat
3) adrenal glands
4) sexual
Answer
Establish a correspondence between the gland of the human body and the type to which it belongs: 1) internal secretion, 2) mixed secretion, 3) external secretion
A) pancreas
B) thyroid
B) lacrimal
D) greasy
D) sexual
E) adrenal gland
Answer
Choose three options. In what cases is humoral regulation carried out?
1) excess carbon dioxide in the blood
2) the body’s reaction to green signal traffic light
3) excess glucose in the blood
4) the body’s reaction to changes in body position in space
5) release of adrenaline during stress
Answer
Establish a correspondence between examples and types of breathing regulation in humans: 1) reflex, 2) humoral. Write numbers 1 and 2 in the order corresponding to the letters.
A) stopping breathing on inspiration when entering cold water
B) an increase in the depth of breathing due to an increase in the concentration of carbon dioxide in the blood
C) cough when food enters the larynx
D) slight holding of breath due to a decrease in the concentration of carbon dioxide in the blood
D) change in breathing intensity depending on the emotional state
E) cerebral vascular spasm due to a sharp increase in oxygen concentration in the blood
