Perm State
Technical University
Department of Physical Culture.
Regulation of nervous activity: humoral and nervous.
Features of the functioning of the central nervous system.
Completed by: student of group ASU-01-1
Kiselev Dmitry
Checked: _______________________
_______________________
Perm 2003
The human body is a single self-developing and self-regulating system.
All living things are characterized by four characteristics: growth, metabolism, irritability and the ability to reproduce themselves. The combination of these characteristics is characteristic only of living organisms. Man, like all other living beings, also has these abilities.
Normal healthy person does not notice the internal processes occurring in his body, for example, how his body processes food. This happens because in the body all systems (nervous, cardiovascular, respiratory, digestive, urinary, endocrine, reproductive, skeletal, muscular) interact harmoniously with each other without the person himself directly interfering in this process. We often have no idea how this happens and how everything is managed very complex processes in our body, how one vital function of the body combines and interacts with another. How nature or God took care of us, what tools they provided our body with. Let's consider the mechanism of control and regulation in our body.
In a living organism, cells, tissues, organs and organ systems work as a single unit. Their coordinated work is regulated by two fundamentally different, but aimed at the same ways: humorally (from lat. "humor"– liquid: through blood, lymph, intercellular fluid) and nervously. Humoral regulation is carried out using biologically active substances– hormones. Hormones are secreted by endocrine glands. The advantage of humoral regulation is that hormones are delivered through the blood to all organs. Nervous regulation is carried out by organs of the nervous system and acts only on the “target organ”. Nervous and humoral regulation carries out the interconnected and coordinated work of all organ systems, so the body functions as a single whole.
Humoral system
The humoral system for regulating metabolism in the body is a combination of endocrine and mixed secretion glands, as well as ducts that allow biologically active substances (hormones) to reach blood vessels or directly the organs that are affected.
Below is a table showing the main endocrine and mixed glands and the hormones they secrete.
Gland | Hormone | Location | Physiological effect |
Thyroid | Thyroxine | Whole body | Accelerates metabolism and O2 exchange in tissues |
Thyroid calcitonin | Exchange of Ca and P |
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Parathyroid | Parathyroid hormone | Bones, kidneys, gastrointestinal tract | Exchange of Ca and P |
Pancreas | Whole body | Regulates carbohydrate metabolism, stimulates protein synthesis |
|
Glucagon | Stimulates the synthesis and breakdown of glycogen |
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Adrenal glands (cortex) | Cortisone | Whole body | Carbohydrate metabolism |
Aldosterone | Kidney tubules | Exchange of electrolytes and water |
|
Adrenal glands (medulla) | Adrenalin | Cardiac muscles, smooth muscle arterioles | Increases the frequency and strength of heart contractions, arteriolar tone, increases blood pressure, stimulates the contraction of many smooth muscles |
Liver, skeletal muscles | Stimulates glycogen breakdown |
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Adipose tissue | Stimulates lipid breakdown |
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Norepinephrine | Arterioles | Increases arteriolar tone and blood pressure |
|
Pituitary gland (anterior lobe) | Somatotropin | Whole body | Accelerates muscle and bone growth, stimulates protein synthesis. Affects the metabolism of carbohydrates and fats |
Thyrotropin | Thyroid gland | Stimulates the synthesis and secretion of hormones thyroid gland |
|
Corticotropin | Adrenal cortex | Stimulates the synthesis and secretion of adrenal hormones |
|
Pituitary gland (posterior lobe) | Vasopressin | Kidney collecting ducts | Facilitates reabsorption of water |
Arterioles | Increases tone, increases blood pressure |
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Oxytocin | Smooth muscle | Muscle contraction |
As can be seen from the table below, the endocrine glands influence both ordinary organs and other endocrine glands (this ensures self-regulation of the activity of the endocrine glands). The slightest disturbances in the activity of this system lead to developmental disorders the whole system organs (for example, with hypofunction of the pancreas, diabetes mellitus, and with hyperfunction of the anterior pituitary gland, gigantism can develop).
A lack of certain substances in the body can lead to an inability to produce certain hormones in the body and, as a result, developmental disorders. For example, insufficient intake of iodine (J) in the diet can lead to the inability to produce thyroxine (hypothyroidism), which can lead to the development of diseases such as myxedema (dry skin, hair loss, decreased metabolism) and even cretinism (stunted growth, mental development).
Nervous system
The nervous system is the unifying and coordinating system of the body. It includes the head and spinal cord, nerves and associated structures, e.g. meninges(layers of connective tissue around the brain and spinal cord).
Despite the well-defined functional separation, the two systems are largely related.With the help of the cerebrospinal system (see below), we feel pain, temperature changes (heat and cold), touch, perceive the weight and size of objects, feel the structure and shape, the position of body parts in space, feel vibration, taste, smell, light and sound. In each case, stimulation of the sensory endings of the corresponding nerves causes a stream of impulses that are transmitted by individual nerve fibers from the site of the stimulus to the corresponding part of the brain, where they are interpreted. When any of the sensations is formed, impulses spread across several neurons separated by synapses until they reach conscious centers in the cerebral cortex.
In the central nervous system, the received information is transmitted by neurons; the pathways they form are called tracts. All sensations, except visual and auditory, are interpreted in the opposite half of the brain. For example, touch right hand projects to the left hemisphere of the brain. Sound sensations coming from each side enter both hemispheres. Visually perceived objects are also projected into both sides of the brain.
The figures on the left show the anatomical location of the nervous system organs. The figure shows that the central part of the nervous system (brain and spinal cord) are concentrated in the head and spinal canal, while the organs of the peripheral nervous system (nerves and ganglia) are dispersed throughout the body. This structure of the nervous system is the most optimal and has been developed evolutionarily.
Conclusion
The nervous and humoral systems have the same goal - to help the body develop and survive in changing environmental conditions, so it makes no sense to talk separately about nervous or humoral regulation. There is a unified neurohumoral regulation that uses “humoral” and “nervous mechanisms” for regulation. “Humoral mechanisms” set the general direction in the development of the body’s organs, and “nervous mechanisms” make it possible to correct the development of a specific organ. It is wrong to assume that nervous system given to us only to think, it is a powerful tool that also unconsciously regulates such vital biological processes as food processing, biological rhythms and much more. Amazingly, even the most intelligent and active person uses only 4% of his brain capacity. The human brain is a unique mystery that has been struggled with since ancient times to the present day and, perhaps, will continue to be wrestled with for thousands of years.
List of used literature:
1. "General Biology" edited by; ed. "Enlightenment" 1975
3. Encyclopedia "Around the World"
4. Personal notes on biology grades 9-11
The subject of physiology, its connection with other sciences
Physiology is the science of the functions and mechanisms of activity of cells, tissues, organs, systems and the entire organism as a whole. A physiological function is a manifestation of life activity that has adaptive significance.
physiology as a science is inextricably linked with other disciplines. It is based on knowledge of physics, biophysics and biomechanics, chemistry and biochemistry, general biology, genetics, histology, cybernetics, anatomy. In turn, physiology is the basis of medicine, psychology, pedagogy, sociology, theory and methodology physical education. In the process of development of physiological science, various special sections of general physiology emerged: labor physiology, sports physiology, aerospace physiology, underwater labor physiology, age-related physiology, psychophysiology, etc.
General physiology represents the theoretical basis of sports physiology. It describes the basic patterns of activity of the body of people of different ages and genders, various functional states, mechanisms of operation of individual organs and systems of the body and their interaction. Its practical significance lies in the scientific substantiation of the age stages of development of the human body, the individual characteristics of individual people, the mechanisms of manifestation of their physical and mental abilities, the features of control and the ability to manage the functional state of the body. Physiology reveals the consequences of bad habits in humans, substantiates ways of prevention functional disorders and maintaining health. Knowledge of physiology helps teachers and coaches in the processes of sports selection and sports orientation, in predicting the success of an athlete’s competitive activity, in the rational construction of the training process, in ensuring the individualization of physical activity and opens up the possibility of using the body’s functional reserves.
Research methods in physiology
To study various processes and functions of a living organism in physiology, methods of observation and experiment are used.
Observation - a method of obtaining information by direct, usually visual, recording of physiological phenomena and processes occurring under certain conditions.
Experiment- a method of obtaining new information about cause-and-effect relationships between phenomena and processes under controlled and controlled conditions. An acute experiment is one that is carried out for a relatively short period of time. An experiment that lasts for a long time (days, weeks, months, years) is called chronic.
Observation method
The essence of this method is to assess the manifestation of a certain physiological process, the function of an organ or tissue in natural conditions. This is the very first method that originated in Ancient Greece. In Egypt, during mummification, corpses were opened and the priests analyzed the condition of various organs in connection with previously recorded data on pulse rate, quantity and quality of urine and other indicators in the people they observed.
Currently, scientists, conducting observational research, use a number of simple and complex devices in their arsenal (application of fistulas, implantation of electrodes), which makes it possible to more reliably determine the functioning mechanism of organs and tissues. For example, observing activities salivary gland, you can determine how much saliva is secreted over a certain period of the day, its color, thickness, etc.
However, observation of the phenomenon does not answer the question of how this or that physiological process or function is carried out.
The observational method is more widely used in zoopsychology and ethology.
Experimental method
A physiological experiment is a targeted intervention in an animal’s body in order to determine the effect various factors to its individual functions. Such intervention sometimes requires surgical training animal, which can be acute (vivisection) or chronic (experimental surgical) form. Therefore, experiments are divided into two types: acute (vivisection) and chronic.
The experimental method, in contrast to the observational method, makes it possible to find out the reason for the implementation of a process or function.
Vivisection carried out on early stages development of physiology in immobilized animals without the use of anesthesia. But starting from the 19th century. In acute experiments, general anesthesia was used.
An acute experiment has its advantages and disadvantages. The advantages include the ability to simulate different situations and obtain results in a relatively short time. The disadvantages include the fact that in an acute experiment the influence of the central nervous system on the body is excluded when using general anesthesia and the integrity of the body’s response to various influences is disrupted. In addition, animals often have to be euthanized after an acute experiment.
Therefore, methods were later developed chronic experiment, in which long-term observation of animals is carried out after surgical intervention and recovery of the animal.
Academician I.P. Pavlov developed a method of applying fistulas to hollow organs (stomach, intestines, bladder). The use of the fistula technique made it possible to elucidate the functioning mechanisms of many organs. Under sterile conditions, the anesthetized animal is surgery, allowing access to a specific internal organ, a fistula tube is implanted or taken out and the gland duct is sutured to the skin. The actual experience begins after healing postoperative wound and recovery of the animal, when physiological processes return to normal. Thanks to this technique, it became possible to study the picture of physiological processes in natural conditions for a long time.
The experimental method, like the observation method, involves the use of simple and complex modern equipment, instruments included in systems designed to influence the object and record various manifestations life activity.
Invention of the kymograph and development of the graphic recording method blood pressure German scientist K. Ludwig discovered in 1847 new stage in the development of physiology. The kymograph made it possible to carry out an objective recording of the process being studied.
Later, methods were developed for recording contractions of the heart and muscles (T. Engelman) and a method for recording changes in vascular tone (plethysmography).
Objective graphic registration bioelectric phenomena became possible thanks to the string galvanometer invented by the Dutch physiologist Einthoven. He was the first to record an electrocardiogram on photographic film. Graphic recording of bioelectric potentials served as the basis for the development of electrophysiology. Currently, electroencephalography is widely used in practice and scientific research.
An important stage in the development of electrophysiology was the invention of microelectrodes. Using micromanipulators, they can be introduced directly into a cell and bioelectric potentials can be recorded. Microelectrode technology has made it possible to decipher the mechanisms of generation of biopotentials in cell membranes.
The German physiologist Dubois-Reymond is the founder of the method of electrical stimulation of organs and tissues using an induction coil for dosed electrical stimulation of living tissues. Currently, electronic stimulators are used for this, making it possible to receive electrical impulses of any frequency and strength. Electrical stimulation has become important method studies of the functions of organs and tissues.
Experimental methods include many physiological methods.
Removal(extirpation) of an organ, for example a certain endocrine gland, makes it possible to determine its effect on various organs and systems of the animal. Removing various areas of the cerebral cortex allowed scientists to determine their effect on the body.
Modern advances physiology were due to the use of radio-electronic technology.
Implantation of electrodes into different parts of the brain helped to establish the activity of various nerve centers.
Introduction radioactive isotopes into the body allows scientists to study the metabolism of various substances in organs and tissues.
Tomographic method using nuclear magnetic resonance is very important for elucidating the mechanisms of physiological processes at the molecular level.
Biochemical And biophysical methods help to accurately identify various metabolites in organs and tissues of animals in normal and pathological states.
Knowledge quantitative characteristics various physiological processes and relationships between them made it possible to create their mathematical models. With the help of these models, physiological processes are reproduced on a computer and studied various options reactions.
3. Stages of development of physiology. Analytical and systematic approach to the study of body functions.
In the development of physiology, two stages are conventionally distinguished:
before scientific (until 1628);
scientific (after 1628).
Pre-scientific stage of development of physiology. Representatives of the pre-scientific stage can be considered famous ancient scientists Hippocrates, Avicena, Galen, Paracelsus and many others. Hippocrates and Galen, for example, developed ideas about the types of human behavior (ideas about choleric, sanguine, melancholic and phlegmatic). Avicena developed a number of original ideas about individual health and ways to strengthen it.
Scientific stage of development of physiology. Date The beginning of the scientific stage of physiology is considered the date of publication of the work of the famous English physician and physiologist William Harvey, “Anatomical Studies on the Movement of the Heart and Blood in Animals” (1628). In this work, for the first time, W. Harvey formulated ideas about the movement of blood in animals through the systemic circulation. Moreover, all the data were obtained experimentally using a new method for that time - the vivisection method (literally, the term vivisection means live cutting).
An important milestone in the development of physiology can be considered the work of the famous French scientist Rene Descartes (1596-1650), who first formulated ideas about the reflective mechanism, which was later called the reflex by the Czech scientist I. Prochazka (1749-1820).
Analytical physiology examined individual organs and their functions - the way of organizing the activities of these organs, their functional significance in the life of the organism.
Combining and integrating all acquired biological knowledge, physiology provided a systematic approach to the study of the life activity of an organism, considering it as a complex, holistic and dynamic system that actively interacts with the environment.
5. General properties of excitable tissues. Types of irritants
A special place in physiology is given to excitable tissues. Not all tissues in the body are able to respond equally quickly to stimuli. Only some of them, in the process of evolution, have developed this property - a quick response to the action of a stimulus.
An irritant is understood as any change in the conditions of the external and internal environment, if it occurs suddenly, has sufficient strength, is maintained for a certain time, and causes reversible changes in the structure and activity of living tissues and cells. The process of exposure of living structures to a stimulus is called irritation.
There are three groups of irritants: physical, physico-chemical and chemical. Particularly highlighted as an irritant nerve impulse.
By physiological significance All stimuli are divided into adequate and inadequate. Adequate are stimuli that act on the body and its structures in natural conditions, and the structures of the body are adapted to the perception of this stimulus. Inadequate are irritants that, under natural conditions, do not affect the body, and the structures of the body are not adapted to their perception. Therefore, such irritants most often cause disruption of body function.
Tissues and cells of the body that are specially adapted to carry out rapid responses to the action of a stimulus are called excitable tissues. These include nervous, glandular and muscle tissue.
Excitable tissues have a number of specific properties: excitability and conductivity.
Excitability is the ability of excitable tissue to respond by changing its structure and activity to the action of a stimulus, i.e. respond to a special biological reaction called excitement.
Excitation is the response of excitable tissue to the action of a pathogen, manifested in a combination of physical, physicochemical, chemical, metabolic processes and changes in activity. Excitation is a wave-like process that manifests itself in different excitable tissues in a specific way: in muscle tissue - by contraction, in glandular tissue - by the formation and release of secretions, in nervous tissue - by the emergence and conduction of a nerve impulse.
The development of excitation is accompanied by a short-term disappearance of excitability. Then it quickly recovers.
An obligatory and general sign of excitation of excitable tissues is the occurrence of a biological current of action, i.e. bioelectric phenomena.
Conductivity is the property of excitable tissue to actively conduct an excitation wave. For example, the motor nerve of a cat conducts excitation at a speed of 1200 cm/s.
nervous and humoral regulation of functions. Features, meaning.
Humoral regulation carried out through the body's fluids (blood (humor), lymph, intercellular, cerebrospinal fluid) with the help of various biologically active substances that are secreted by specialized cells, tissues or organs. This type of regulation can be carried out at the level of organ structures - local self-regulation, or provide generalized effects through the hormonal regulation system. Chemical substances that are formed in specialized tissues and have specific functions enter the blood. Among these substances there are: metabolites, mediators, hormones. They can act locally or remotely. For example, ATP hydrolysis products, the concentration of which increases with increasing functional activity of cells, cause dilation of blood vessels and improve the trophism of these cells. A particularly important role is played by hormones - secretion products of special endocrine organs. The endocrine glands include: the pituitary gland, the thyroid and parathyroid glands, the islet apparatus of the pancreas, the adrenal cortex and medulla, the gonads, the placenta and the pineal gland. Hormones influence metabolism, stimulate morphological processes, differentiation, growth, metamorphosis of cells, include certain activities of executive organs, change the intensity of activity of executive organs and tissues. The humoral pathway of regulation acts relatively slowly, the speed of the response depends on the rate of formation and secretion of the hormone, its penetration into the lymph and blood, and the speed of blood flow. The local effect of the hormone is determined by the presence of a specific receptor for it. The duration of action of the hormone depends on the rate of its destruction in the body. In various cells of the body, including the brain, neuropeptides are formed that affect the behavior of the body, a whole series various functions and regulate the secretion of hormones.
Nervous regulation carried out through the nervous system, is based on the processing of information by neurons and its transmission along the nerves. Has the following features:
Greater speed of development of action;
Communication accuracy;
High specificity - a strictly defined number of components needed at a given moment is involved in the reaction.
Nervous regulation is carried out quickly, with the direction of the signal to a specific addressee. The transmission of information (neuron action potentials) occurs at speeds of up to 80-120 m/s without a decrease in amplitude or loss of energy. Somatic and autonomic functions of the body are subject to nervous regulation. The basic principle of nervous regulation is reflex. The nervous mechanism of regulation phylogenetically arose later than the local and humoral ones and provides high accuracy, speed and reliability of the response. It is the most advanced regulatory mechanism.
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body
Regulation of the functions of cells, tissues and organs, the relationship between them, i.e. integrity of the organism, and unity of the organism and external environment carried out by the nervous system and the humoral pathway. In other words, we have two mechanisms for regulating functions - nervous and humoral.
Nervous regulation is carried out by the nervous system, the brain and spinal cord through the nerves that supply all the organs of our body. The body is constantly exposed to certain irritations. The body responds to all these irritations with a certain activity or, as is customary, the body’s function adapts to constantly changing environmental conditions. Thus, a decrease in air temperature is accompanied not only by a narrowing of blood vessels, but also by an increase in metabolism in cells and tissues and, consequently, an increase in heat generation. Thanks to this, a certain balance is established between heat transfer and heat generation, the body does not become hypothermic, and body temperature remains constant. Irritation of the taste buds of the mouth by food causes the release of saliva and other digestive juices. under the influence of which food is digested. Thanks to this, the necessary substances enter the cells and tissues, and a certain balance is established between dissimilation and assimilation. This principle is used to regulate other body functions.
Nervous regulation is reflexive in nature. Various irritations are perceived by receptors. The resulting excitation from the receptors is transmitted along the sensory nerves to the central nervous system, and from there along the motor nerves to the organs that carry out certain activities. Such responses of the body to irritations carried out through the central nervous system. called reflexes. The path along which excitation is transmitted during a reflex is called a reflex arc. Reflexes are varied. I.P. Pavlov divided all reflexes into unconditional and conditional. Unconditioned reflexes are innate reflexes that are inherited. An example of such reflexes are vasomotor reflexes (constriction or dilation of blood vessels in response to skin irritation by cold or heat), salivation reflex (secretion of saliva when taste buds are irritated by food) and many others.
Conditioned reflexes are acquired reflexes; they are developed throughout the life of an animal or a person. These reflexes occur
only under certain conditions and can disappear. Example conditioned reflexes is the secretion of saliva at the sight of a beggar, when smelling food, and in a person even when talking about it.
Humoral regulation (Humor - liquid) is carried out through blood and other liquids that make up the internal environment of the body, various chemicals that are produced in the body itself or come from the external environment. Examples of such substances are hormones secreted by the endocrine glands and vitamins that enter the body with food. Chemicals are carried by the blood throughout the body and affect various functions, in particular the metabolism of cells and tissues. Moreover, each substance affects a specific process occurring in one or another organ.
The nervous and humoral mechanisms of regulation of functions are interconnected. Thus, the nervous system has a regulatory effect on organs not only directly through the nerves, but also through the endocrine glands, changing the intensity of the formation of hormones in these Organs and their entry into the blood.
In turn, many hormones and other substances affect the nervous system.
In a living organism, nervous and humoral regulation of various functions is carried out according to the principle of self-regulation, i.e. automatically. According to this principle of regulation, blood pressure, constancy of the composition and physicochemical properties of blood, and body temperature are maintained at a certain level. metabolism, activity of the heart, respiratory and other organ systems change in a strictly coordinated manner during physical work etc.
Thanks to this, certain relatively constant conditions are maintained in which the activity of cells and tissues of the body takes place, or in other words, the constancy of the internal environment is maintained.
It should be noted that in humans the nervous system plays a leading role in regulating the vital functions of the body.
Thus, the human body is a single, integral, complex, self-regulating and self-developing biological system that has certain reserve capabilities. At the same time
know that the ability to perform physical work can increase many times, but up to a certain limit. Whereas mental activity actually has no restrictions in its development.
Systematic muscular activity allows, by improving physiological functions mobilize the body's reserves, the existence of which many are not even aware of. It should be noted that there is a reverse process: a decrease in the functional capabilities of the body and accelerated aging with a decrease in physical activity.
During physical exercise Higher nervous activity and the functions of the central nervous system are improved. neuromuscular. cardiovascular, respiratory, excretory and other systems, metabolism and energy, as well as the system of their neurohumoral regulation.
The human body, using the properties of self-regulation of internal processes under external influence, implements the most important property - adaptation to changing external conditions, which is a determining factor in the ability to develop physical qualities and motor skills during training.
Let us consider in more detail the nature of physiological changes during training.
Physical activity leads to a variety of metabolic changes, the nature of which depends on the duration, power of work and the number of muscles involved. During physical activity, catabolic processes, mobilization and use of energy substrates predominate, and intermediate metabolic products accumulate. The rest period is characterized by the predominance of anabolic processes, accumulation of nutrient reserves, and enhanced protein synthesis.
The speed of recovery depends on the magnitude of changes occurring during operation, that is, on the magnitude of the load.
During the rest period, metabolic changes that occur during muscle activity are eliminated. If during physical activity catabolic processes predominate, the mobilization and use of energy substrates occurs, and intermediate metabolic products accumulate, then the rest period is characterized by the predominance of anabolic processes, the accumulation of nutrient reserves, and increased protein synthesis.
In the post-working period, the intensity of aerobic oxidation increases, oxygen consumption increases, i.e. the oxygen debt is eliminated. The oxidation substrate is intermediate metabolic products formed during muscle activity, lactic acid, ketone bodies, keto acids. Carbohydrate reserves during physical work, as a rule, are significantly reduced, so the main substrate for oxidation becomes fatty acids. Due to the increased use of lipids during the recovery period, the respiratory quotient decreases.
The recovery period is characterized by increased protein biosynthesis, which is inhibited during physical work; the formation and removal from the body of the final products of protein metabolism (urea, etc.) also increases.
The speed of recovery depends on the magnitude of changes that occur during operation, i.e. on the load value, which is schematically presented in Fig. 1
Fig. 1 Scheme of the processes of consumption and restoration of sources
energy during muscular activity of military intensity
The recovery of changes that occur under the influence of low- and medium-intensity loads is slower than after high- and extreme-intensity loads, which is explained by deeper changes during the period of work. After increased intensity loads, the observed metabolic rate of substances not only reaches baseline, but also exceeds it. This increase above the initial level is called super-recovery (super-compensation). It is registered only when the load exceeds a certain level, i.e. when the resulting metabolic changes affect the genetic apparatus of the cell. The severity of super-recovery and its duration are directly dependent on the intensity of the load.
The phenomenon of hyperactivity is important: a mechanism of adaptation (of an organ) to changed operating conditions and is important for understanding the biochemical foundations of sports training. It should be noted that, as a general biological pattern, it extends not only to the accumulation of energy material, but also to the synthesis of proteins, which, in particular, manifests itself in the form of working hypertrophy of skeletal muscles and cardiac muscles. After intense exercise, the synthesis of a number of enzymes increases (enzyme induction), the concentration of creatine phosphate and myoglobin increases, and a number of other changes occur.
It has been established that active muscle activity causes increased activity of the cardiovascular, respiratory and other body systems. During any human activity, all organs and systems of the body act in concert, in close unity. This relationship is carried out through the nervous system and humoral (fluid) regulation.
The nervous system regulates the body's activities through bioelectric impulses. The main nervous processes are excitation and inhibition that occur in nerve cells. Excitation- the active state of nerve cells when they transmit silt” and direct the nerve impulses themselves to other cells: nerve, muscle, glandular and others. Braking- a state of nerve cells when their activity is aimed at restoration. Sleep, for example, is a state of the nervous system when the overwhelming number of nerve cells in the central nervous system are inhibited.
Humoral regulation is carried out through the blood through special chemicals (hormones) secreted by the endocrine glands, the concentration ratio CO2 and O2 through other mechanisms. For example, in the pre-launch state, when intense physical activity, the endocrine glands (adrenal glands) secrete a special hormone, adrenaline, into the blood, which enhances the activity of the cardiovascular system.
Humoral and nervous regulation are carried out in unity. The leading role is given to the central nervous system, the brain, which is, as it were, the central headquarters for controlling the vital functions of the body.
2.10.1. Reflex nature and reflex mechanisms of motor activity
The nervous system operates on the principle of a reflex. Inherited reflexes, inherent in the nervous system from birth, in its structure, in the connections between nerve cells, are called unconditioned reflexes. Uniting in long chains, unconditioned reflexes are the basis of instinctive behavior. In humans and higher animals, the basis of behavior is conditioned reflexes, developed in the process of life on the basis of unconditioned reflexes.
Sports and work activity human development, including the acquisition of motor skills, is carried out according to the principle of the relationship of conditioned reflexes and dynamic stereotypes with unconditioned reflexes.
To perform clear, targeted movements, it is necessary to continuously receive signals to the central nervous system about the functional state of the muscles, the degree of their contraction, tension and relaxation, body posture, the position of the joints and the angle of bend in them.
All this information is transmitted from the receptors of the sensory systems and especially from the receptors of the motor sensory system, from the so-called proprioceptors, which are located in muscle tissue, fascia, articular capsules and tendons.
From these receptors, according to the feedback principle and the reflex mechanism, the central nervous system receives full information about the execution of a given motor action and its comparison with a given program.
Every movement, even the simplest one, needs constant correction, which is provided by information coming from proprioceptors and other sensory systems. With repeated repetition of a motor action, impulses from the receptors reach the motor centers in the central nervous system, which accordingly change their impulses going to the muscles in order to improve the movement being learned.
Thanks to such a complex reflex mechanism, motor activity is improved.
Plan:
1. Humoral regulation
2. The hypothalamic-pituitary system as the main mechanism of neurohumoral regulation of hormone secretion.
3. Pituitary hormones
4. Thyroid hormones
5. Parathyroid hormones
6. Pancreatic hormones
7. The role of hormones in the body’s adaptation to stress factors
Humoral regulation- this is a type of biological regulation in which information is transmitted using biologically active substances that are carried throughout the body by blood, lymph, and intercellular fluid.
Humoral regulation differs from nervous regulation:
the information carrier is a chemical substance (in the case of a nervous one - a nerve impulse, PD);
transmission of information is carried out by the flow of blood, lymph, by diffusion (in the case of the nervous system - by nerve fibers);
the humoral signal travels more slowly (with blood flow in the capillaries - 0.05 mm/s) than the nervous signal (up to 120-130 m/s);
the humoral signal does not have such a precise “addressee” (the nervous signal is very specific and precise), affecting those organs that have receptors for the hormone.
Factors of humoral regulation:
"classical" hormones
Hormones of the APUD system
Classic hormones themselves- these are substances synthesized by endocrine glands. These are hormones of the pituitary gland, hypothalamus, pineal gland, adrenal glands; pancreas, thyroid, parathyroid, thymus, gonads, placenta (Fig. I).
Except endocrine glands, in various organs and tissues there are specialized cells that release substances that act on target cells through diffusion, i.e., entering the body locally. These are paracrine hormones.
These include neurons of the hypothalamus, which produce some hormones and neuropeptides, as well as cells of the APUD system, or the system for capturing amine precursors and their decarboxylation. Examples include: liberins, statins, hypothalamic neuropeptides; interstinal hormones, components of the renin-angiotensin system.
2) Tissue hormones secreted by unspecialized cells of various types: prostaglandins, enkephalins, components of the kallikrein-inin system, histamine, serotonin.
3) Metabolic factors- these are nonspecific products that are formed in all cells of the body: lactic acid, pyruvic acid, CO 2, adenosine, etc., as well as decomposition products during intense metabolism: increased content of K +, Ca 2+, Na +, etc.
Functional significance of hormones:
1) ensuring growth, physical, sexual, intellectual development;
2) participation in the adaptation of the body in various changing conditions of the external and internal environment;
3) maintaining homeostasis..
Rice. 1 Endocrine glands and their hormones
Properties of hormones:
1) specificity of action;
2) distant nature of the action;
3) high biological activity.
1. The specificity of action is ensured by the fact that hormones interact with specific receptors located in certain target organs. As a result, each hormone acts only on specific physiological systems or organs.
2. Distance lies in the fact that the target organs on which hormones act are, as a rule, located far from the place of their formation in the endocrine glands. Unlike “classical” hormones, tissue hormones act paracrine, that is, locally, not far from the place of their formation.
Hormones act in very small quantities, which is where their high biological activity. Thus, the daily requirement for an adult is: thyroid hormones - 0.3 mg, insulin - 1.5 mg, androgens - 5 mg, estrogens - 0.25 mg, etc.
The mechanism of action of hormones depends on their structure
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Hormones of protein structure Hormones of steroid structure
Rice. 2 Mechanism of hormonal control
Hormones of protein structure (Fig. 2) interact with receptors of the plasma membrane of the cell, which are glycoproteins, and the specificity of the receptor is determined by the carbohydrate component. The result of the interaction is the activation of protein phosphokinases, which provide
phosphorylation of regulatory proteins, transfer of phosphate groups from ATP to hydroxyl groups of serine, threonine, tyrosine, protein. The final effect of these hormones can be a reduction, enhancement of enzymatic processes, for example, glycogenolysis, increased protein synthesis, increased secretion, etc.
The signal from the receptor with which the protein hormone interacts is transmitted to the protein kinase with the participation of a specific intermediary or second messenger. Such messengers can be (Fig. 3):
1) cAMP;
2) Ca 2+ ions;
3) diacylglycerol and inositol triphosphate;
4) other factors.
Fig.Z. The mechanism of membrane reception of the hormonal signal in the cell with the participation of second messengers.
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Hormones with a steroid structure (Fig. 2) easily penetrate into the cell through the plasma membrane due to their lipophilicity and interact in the cytosol with specific receptors, forming a “hormone-receptor” complex that moves into the nucleus. In the nucleus, the complex disintegrates and hormones interact with nuclear chromatin. As a result of this, interaction with DNA occurs, and then induction of messenger RNA. Due to the activation of transcription and translation 2-3 hours after exposure to the steroid, increased synthesis of induced proteins is observed. In one cell, the steroid affects the synthesis of no more than 5-7 proteins. It is also known that in the same cell steroid hormone can cause induction of the synthesis of one protein and repression of the synthesis of another protein (Fig. 4).
The action of thyroid hormones is carried out through receptors in the cytoplasm and nucleus, as a result of which the synthesis of 10-12 proteins is induced.
Reflation of hormone secretion is carried out by the following mechanisms:
1) direct influence of blood substrate concentrations on gland cells;
2) nervous regulation;
3) humoral regulation;
4) neurohumoral regulation (hypothalamic-pituitary system).
In the regulation of activity endocrine system An important role is played by the principle of self-regulation, which is carried out according to the type of feedback. There are positive (for example, an increase in blood sugar leads to an increase in insulin secretion) and negative feedback (with an increase in the level of thyroid hormones in the blood, the production of thyroid-stimulating hormone and thyrotropin-releasing hormone, which ensure the release of thyroid hormones, decreases).
So, the direct influence of the concentrations of blood substrates on gland cells occurs according to the principle of feedback. If the level of a substance controlled by a specific hormone changes in the blood, then “the tear responds by increasing or decreasing the secretion of this hormone.
Nervous regulation carried out due to the direct influence of the sympathetic and parasympathetic nerves on the synthesis and secretion of hormones (neurohypophysis, adrenal medulla), as well as indirectly, “changing the intensity of the blood supply to the gland. Emotional, mental influences through the structures of the limbic system, through the hypothalamus, can significantly influence the production of hormones.
Hormonal regulation It is also carried out according to the feedback principle: if the level of a hormone in the blood increases, then the release of those hormones that control the content of this hormone decreases, which leads to a decrease in its concentration in blood.
For example, when the level of cortisone in the blood increases, the release of ACTH (a hormone that stimulates the secretion of hydrocortisone) decreases and, as a consequence,
Decrease in its level in the blood. Another example of hormonal regulation could be this: melatonin (pineal gland hormone) modulates the function of the adrenal glands, thyroid gland, gonads, i.e. a certain hormone can influence the content of other hormonal factors in the blood.
The hypothalamic-pituitary system as the main mechanism of neurohumoral regulation of hormone secretion.
The function of the thyroid, gonads, and adrenal cortex is regulated by hormones of the anterior pituitary gland - the adenohypophysis. Here they are synthesized tropic hormones: adrenocorticotropic (ACTH), thyroid-stimulating (TSH), follicle-stimulating (FS) and luteinizing (LH) (Fig. 5).
With some convention, triple hormones also include growth hormone(growth hormone), which affects growth not only directly, but also indirectly through hormones - somatomedins, formed in the liver. All these tropic hormones are so named due to the fact that they ensure the secretion and synthesis of the corresponding hormones of other endocrine glands: ACTH -
glucocorticoids and mineralocorticoids: TSH - thyroid hormones; gonadotropic - sex hormones. In addition, intermedia (melanocyte-stimulating hormone, MCH) and prolactin are formed in the adenohypophysis, which have an effect on peripheral organs.
Rice. 5. Regulation of the endocrine glands of the central nervous system. TL, SL, PL, GL and CL - respectively, thyrotropin-releasing hormone, somatoliberin, prolactoliberin, gonadoliberin and corticoliberin. SS and PS - somatostatin and prolactostatin. TSH - thyroid-stimulating hormone, STH - somatotropic hormone (growth hormone), PR - prolactin, FSH - follicle-stimulating hormone, LH - luteinizing hormone, ACTH - adrenocorticotropic hormone
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Thyroxine Triiodothyronine Androgen Glucocorticoids
Estrogens
In turn, the release of all 7 of these hormones of the adenohypophysis depends on the hormonal activity of neurons in the pituitary zone of the hypothalamus - mainly the paraventricular nucleus (PVN). Hormones are formed here that have a stimulating or inhibitory effect on the secretion of adenohypophysis hormones. Stimulants are called releasing hormones (liberins), inhibitors are called statins. Thyroid-releasing hormone and gonadoliberin were isolated. somatostatin, somatoliberin, prolactostatin, prolactoliberin, melanostatin, melanoliberin, corticoliberin.
Releasing hormones are released from the processes of nerve cells of the paraventricular nucleus, enter the portal venous system of the hypothalamo-pituitary gland and are transported with the blood to the adenohypophysis.
The regulation of the hormonal activity of most endocrine glands is carried out according to the principle of negative feedback: the hormone itself, its amount in the blood, regulates its formation. This effect is mediated through the formation of the corresponding releasing hormones (Fig. 6,7)
In the hypothalamus (supraoptic nucleus), in addition to releasing hormones, vasopressin (antidiuretic hormone, ADH) and oxytocin are synthesized. Which in the form of granules are transported along the nerve processes to the neurohypophysis. The release of hormones into the bloodstream by neuroendocrine cells is due to reflex nerve stimulation.
Rice. 7 Direct and feedbacks in the neuroendocrine system.
1 - slowly developing and long-lasting inhibition of the secretion of hormones and neurotransmitters , as well as behavior change and memory formation;
2 - rapidly developing but long-lasting inhibition;
3 - short-term inhibition
Pituitary hormones
The posterior lobe of the pituitary gland, the neurohypophysis, contains oxytocin and vasopressin (ADH). ADH affects three types of cells:
1) renal tubular cells;
2) smooth muscle cells of blood vessels;
3) liver cells.
In the kidneys, it promotes the reabsorption of water, which means preserving it in the body, reducing diuresis (hence the name antidiuretic), in blood vessels it causes contraction of smooth muscles, narrowing their radius, and as a result, increases blood pressure (hence the name “vasopressin”), in liver - stimulates gluconeogenesis and glycogenolysis. In addition, vasopressin has an antinociceptive effect. ADH is designed to regulate the osmotic pressure of the blood. Its secretion increases under the influence of such factors: increased blood osmolarity, hypokalemia, hypocalcemia, increased decrease in blood volume, decreased blood pressure, increased body temperature, activation of the sympathetic system.
When ADH secretion is insufficient, it develops diabetes insipidus: the volume of urine excreted per day can reach 20 liters.
Oxytocin in women plays the role of a regulator of uterine activity and is involved in lactation processes as an activator of myoepithelial cells. An increase in oxytocin production occurs during the dilation of the cervix at the end of pregnancy, ensuring its contraction during childbirth, as well as during feeding of the baby, ensuring the secretion of milk.
The anterior lobe of the pituitary gland, or adenohypophysis, produces thyroid-stimulating hormone (TSH), somatotropic hormone (GH) or growth hormone, gonadotropic hormones, adrenocorticotropic hormone (ACTH), prolactin, and in the middle lobe - melanocyte-stimulating hormone (MSH) or intermedia.
Growth hormone stimulates protein synthesis in bones, cartilage, muscles and liver. In an immature organism, it ensures growth in length by increasing the proliferative and synthetic activity of cartilage cells, especially in the growth zone of long tubular bones, while simultaneously stimulating the growth of their heart, lungs, liver, kidneys and other organs. In adults, it controls the growth of organs and tissues. STH reduces the effects of insulin. Its release into the blood increases during deep sleep, after muscle exertion, and during hypoglycemia.
The growth effect of growth hormone is mediated by the hormone’s effect on the liver, where somatomedins (A, B, C) or growth factors are formed, which cause the activation of protein synthesis in cells. The value of growth hormone is especially great during the period of growth (prepubertal, pubertal periods).
During this period, GH agonists are sex hormones, an increase in the secretion of which contributes to a sharp acceleration of bone growth. However, prolonged formation of large quantities of sex hormones leads to the opposite effect - to the cessation of growth. An insufficient amount of GH leads to dwarfism (nanism), and an excessive amount leads to gigantism. Growth of some adult bones may resume if there is excessive secretion of GH. Then the proliferation of cells in the germ zones resumes. What causes growth
In addition, glucocorticoids inhibit all components of the inflammatory reaction - they reduce capillary permeability, inhibit exudation, and reduce the intensity of phagocytosis.
Glucocorticoids sharply reduce the production of lymphocytes, reduce the activity of T-killers, the intensity of immunological surveillance, hypersensitivity and sensitization of the body. All this allows us to consider glucocorticoids as active immunosuppressants. This property is used clinically to relieve autoimmune processes, to reduce immune defense host organism.
Glucocorticoids increase sensitivity to catecholamines and increase secretion hydrochloric acid and pepsin. An excess of these hormones causes bone demineralization, osteoporosis, loss of Ca 2+ in the urine, and reduces Ca 2+ absorption. Glucocorticoids affect the function of the internal nervous system - they increase the activity of information processing and improve the perception of external signals.
Mineralocorticoids(aldosgerone, deoxycorticosterone) are involved in the regulation of mineral metabolism. The mechanism of action of aldosterone is associated with the activation of protein synthesis involved in the reabsorption of Na + - Na +, K h -ATPase. By increasing reabsorption and reducing it for K + in the distal tubules of the kidney, salivary and gonads, aldosterone promotes the retention of Na and SG in the body and the removal of K + and H from the body. Thus, aldosterone is a sodium-sparing and also a kaliuretic hormone. Due delay of Ia\ and, after it, water, it contributes to an increase in blood volume and, as a result, an increase in blood pressure. Unlike glucocorticoids, mineralocorticoids contribute to the development of inflammation, because they increase capillary permeability.
Sex hormones The adrenal glands perform the function of developing the genital organs and the appearance of secondary sexual characteristics during the period when the gonads are not yet developed, that is, in childhood and in old age.
The hormones of the adrenal medulla - adrenaline (80%) and norepinephrine (20%) - cause effects that are largely identical to the activation of the nervous system. Their action is realized through interaction with a- and beta-adrenergic receptors. Consequently, they are characterized by activation of the heart, constriction of skin vessels, dilation of the bronchi, etc. Adrenaline affects carbohydrate and fat metabolism, enhancing glycogenolysis and lipolysis.
Catecholamines are involved in the activation of thermogenesis, in the regulation of the secretion of many hormones - they increase the release of glucagon, renin, gastrin, parathyroid hormone, calcitonin, thyroid hormones; reduce insulin release. Under the influence of these hormones, the performance of skeletal muscles and the excitability of receptors increase.
With hyperfunction of the adrenal cortex in patients, secondary sexual characteristics noticeably change (for example, in women, male sexual characteristics may appear - a beard, mustache, timbre of voice). Obesity (especially in the neck, face, and torso), hyperglycemia, water and sodium retention in the body, etc. are observed.
Hypofunction of the adrenal cortex causes Addison's disease - a bronze tint of the skin (especially the face, neck, hands), loss of appetite, vomiting, increased sensitivity to cold and pain, high susceptibility to infections, increased diuresis (up to 10 liters of urine per day), thirst, decreased performance.
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The organism is a single whole. The unity of the body is ensured by a unified metabolism, a unified neuro-humoral regulation, and a common hemo- and lymphocirculation system for all tissues. The organism exists in close interaction with the environment, exchanging substances, energy, and information with it. The existence of an organism, relatively independent of the environment, is ensured by the body’s ability to maintain indicators of the internal environment at a constant level (homeostasis). The most important indicators of homeostasis include normal blood concentrations of minerals and nutrients, metabolites, hydrogen ions, blood cells and other indicators.
Physiological regulation is the control of body functions in order to adapt it to environmental conditions. Regulation of body functions is the basis for ensuring the constancy of the body’s internal environment and its adaptation to changing conditions of existence and is carried out on the principle of self-regulation through the formation of functional systems. The function of systems and the body as a whole is called activity aimed at preserving the integrity and properties of the system. Functions are characterized quantitatively and qualitatively.
The basis of physiological regulation is the transmission and processing of information. The term “information” refers to any message about facts and events occurring in the environment and the human body. Self-regulation is understood as this type of regulation when the deviation of the regulated parameter is a stimulus for its restoration.
To implement the principle of self-regulation, the interaction of the following components of functional systems is necessary:
Adjustable parameter (object of regulation, constant).
Control devices that monitor the deviation of this parameter under the influence of external and internal factors.
Regulatory devices that provide directed action on the activity of organs on which the restoration of the deviated parameter depends.
Execution apparatuses are organs and organ systems, changes in the activity of which in accordance with regulatory influences lead to the restoration of the initial value of the parameter.
“Reverse afferentation carries information to the regulatory apparatus about the achievement or failure to achieve a useful result, about the return or non-return of a deviated parameter to the norm. Thus, the regulation of functions is carried out by a system that consists of individual elements: a control device (CNS, endocrine cell), communication channels ( nerves, liquid internal environment), sensors that perceive the action of external and internal environmental factors (receptors), structures that perceive information from output channels (cell receptors) and executive organs.
The regulatory system in the body has a three-level structure. The first level of regulation consists of relatively autonomous local systems that maintain constants. The second level of the regulatory system provides adaptive reactions in connection with changes in the internal environment; at this level, the optimal operating mode is ensured physiological systems to adapt the body to the external environment. The third level of regulation is implemented by the behavioral reactions of the body and ensures the optimization of its vital functions.
There are four types of regulation: mechanical, humoral, nervous, neurohumoral.
Physical (mechanical) regulation is realized through mechanical, electrical, optical, sound, electromagnetic, thermal and other processes (for example, filling the cavities of the heart with an additional volume of blood leads to a greater degree of stretching of their walls and to a stronger contraction of the myocardium). The most reliable regulatory mechanisms are local. They are realized through the physical and chemical interaction of organ structures. For example, in a working muscle, as a result of the release of chemical metabolites and heat by myocytes, dilation of blood vessels occurs, which is accompanied by an increase in the volumetric velocity of blood flow and an increase in the supply of myocytes with nutrients and oxygen. Local regulation can be carried out with the help of biologically active substances (histamine), tissue hormones (prostaglandins).
Humoral regulation carried out through the body's fluids (blood (humor), lymph, intercellular, cerebrospinal fluid) with the help of various biologically active substances that are secreted by specialized cells, tissues or organs. This type of regulation can be carried out at the level of organ structures - local self-regulation, or provide generalized effects through the hormonal regulation system. Chemical substances that are formed in specialized tissues and have specific functions enter the blood. Among these substances there are: metabolites, mediators, hormones. They can act locally or remotely.
For example, ATP hydrolysis products, the concentration of which increases with increasing functional activity of cells, cause dilation of blood vessels and improve the trophism of these cells. Hormones, the secretion products of special endocrine organs, play a particularly important role. The endocrine glands include: the pituitary gland, the thyroid and parathyroid glands, the islet apparatus of the pancreas, the adrenal cortex and medulla, the gonads, the placenta and the pineal gland.
Hormones influence metabolism, stimulate morphological processes, differentiation, growth, metamorphosis of cells, include certain activities of executive organs, change the intensity of activity of executive organs and tissues. The humoral pathway of regulation acts relatively slowly, the speed of the response depends on the rate of formation and secretion of the hormone, its penetration into the lymph and blood, and the speed of blood flow. The local effect of the hormone is determined by the presence of a specific receptor for it. The duration of action of the hormone depends on the rate of its destruction in the body. In various cells of the body, including the brain, neuropeptides are formed that affect the behavior of the body, a number of different functions and regulate the secretion of hormones.
Nervous regulation carried out through the nervous system, is based on the processing of information by neurons and its transmission along the nerves.
Has the following features:
Greater speed of development of action;
Communication accuracy;
High specificity - a strictly defined number of components needed at a given moment is involved in the reaction.
Nervous regulation is carried out quickly, with the direction of the signal to a specific addressee. The transmission of information (neuron action potentials) occurs at speeds of up to 80-120 m/s without a decrease in amplitude or loss of energy. Somatic and autonomic functions of the body are subject to nervous regulation. The basic principle of nervous regulation is reflex. The nervous mechanism of regulation phylogenetically arose later than the local and humoral ones and provides high accuracy, speed and reliability of the response. It is the most advanced regulatory mechanism.
In the process of evolution, the nervous and humoral types of correlations were combined into a neurohumoral form, when the urgent involvement of organs in the process of action through nervous correlation is supplemented and prolonged by humoral factors.
Nervous and humoral correlations play a leading role in unification (integration) components(components) of the organism into a single wholeorganism. At the same time, they seem to complement each other with their characteristics. The humoral connection is generalized. It is simultaneously implemented throughout the entire body. The nervous connection is directional in nature, it is the most selective and is realized in each specific case mainly at the level of certain components of the body.
Creative connections ensure the exchange of macromolecules between cells, which are capable of exerting a regulatory influence on the processes of metabolism, differentiation, growth, development, and functioning of cells and tissues. Through creative connections, the influence of kalons is exerted - proteins that suppress the synthesis of nucleic acids and cell division.
Metabolites, through a feedback mechanism, influence intracellular metabolism and cell functions and the functioning of nearby structures. For example, during intense muscle work, milk and pyruvic acid, formed in a muscle cell under conditions of oxygen deficiency, lead to the expansion of muscle microvessels, to an increase in the flow of blood, nutrients and oxygen, which improves the nutrition of muscle cells. At the same time, they stimulate metabolic pathways for their use, reduce contractility muscles.
The neuroendocrine system ensures that the metabolic, physical functions and behavioral reactions of the body correspond to environmental conditions, supports the processes of differentiation, growth, development, and regeneration of cells; generally contribute to the preservation and development of both the individual and the biological species as a whole. Dual (nervous and endocrine) regulation ensures, through a duplication mechanism, the reliability of regulation, high response speed through the nervous system and the duration of the response over time through the release of hormones.
Phylogenetically, the most ancient hormones are produced by nerve cells; a chemical signal and a nerve impulse are often interconvertible. Hormones, being neuromodulators, influence the effects of many mediators in the central nervous system (gastrin, cholecystokinin, VIP, GIP, neurotensin, bombesin, substance P, opiomelanocortins - ACTH, beta-, gamma-lipotropins, alpha-, beta-, gamma-endorphins, prolactin, somatotropin). Hormone-producing neurons have been described.
The basis of nervous and humoral regulation is the principle of a ring connection, which in biological systems was primarily shown by the Soviet physiologist P.K. Anokhin. Positive and negative feedback ensures an optimal level of functioning - strengthening weak responses and limiting over-strong ones.
The division of regulatory mechanisms into nervous and humoral is conditional.
In the body, these mechanisms are inseparable:
1) Information about the state of the external and internal environment, as a rule, is perceived by elements of the nervous system, and after processing in neurons, both nervous and humoral regulatory pathways can be used as executive organs.
2) The activity of the endocrine glands is controlled by the nervous system. In turn, the metabolism, development and differentiation of neurons is carried out under the influence of hormones.
3) Action potentials at the points of contact between the neuron and the working cell cause the secretion of a mediator, which, through the humoral link, changes the function of the cell. Thus, in the body there is a unified neurohumoral regulation with priority significance of the nervous system. The body responds to the action of each stimulus with a complex biological reaction as a whole. This is achieved by the interaction of all systems, tissues and cells of the body. The interaction is ensured by local, humoral and neural regulatory mechanisms
The human nervous system is divided into central (brain and spinal cord) and peripheral. The central nervous system ensures the individual adaptation of the body to its environment, adaptation of the body, behavior of the body in accordance with the constitution and its needs, ensures the integration and unification of organs into a single whole based on the perception, evaluation, comparison, analysis of information coming from the external and internal environment of the body . The peripheral nervous system provides tissue trophism and has a direct impact on the structure and functional activity of organs.
