Regulatory systems of the body. Regulatory systems of the body mechanisms of regulation of the body humoral Regulatory system

Basic concepts and key terms: regulatory systems, nervous, endocrine, immune systems.

Remember! What is the regulation of human body functions?

Regulation (from Latin regulation) - to put in order, to arrange.

Think!

The human body is a complex system. It contains billions of cells, millions of structural units, thousands of organs, hundreds of functional systems, dozens of physiological systems. And why do they all work harmoniously as a single whole?

What are the features of the regulatory systems of the human body?

REGULATORY SYSTEMS

a set of organs that have a leading influence on the activity of physiological systems, organs and cells. These systems have structural and functional features related to their purpose.

Regulatory systems have central and peripheral sections. Leadership teams are formed in central bodies, and peripheral bodies ensure their distribution and transfer to working bodies for implementation (the principle of centralization).

To monitor the execution of commands, the central bodies of regulatory systems receive feedback from the working bodies. This feature of the activity of biological systems is called the feedback principle.

Information from regulatory systems throughout the body is transmitted in the form of signals. Therefore, the cells of such systems have the ability to produce electrical impulses and chemicals, encode and distribute information.

Regulatory systems regulate functions in accordance with changes in the external or internal environment. Therefore, the leadership teams that are sent to the authorities have either a stimulating or retarding nature (the principle of double action).

Such features in the human body are characteristic of three systems - nervous, endocrine and immune. And they are the regulatory systems of our body.

So, the main features of regulatory systems are:

1) the presence of central and peripheral sections; 2) the ability to produce guidance signals; 3) activities based on feedback; 4) double mode of regulation.

How is the regulatory activity of the nervous system organized?

The nervous system is a set of human organs that perceive, analyze and ensure the activity of physiological organ systems in a very fast manner. According to its structure, the nervous system is divided into two parts - central and peripheral. The central cord includes the brain and spinal cord, and the peripheral cord includes the nerves. The activity of the nervous system is reflexive, carried out with the help of nerve impulses arising in nerve cells. A reflex is the body's response to stimulation that occurs with the participation of the nervous system. Any activity of physiological systems is reflexive in nature. Thus, with the help of reflexes, the secretion of saliva to tasty food, withdrawal of the hand from the thorns of a rose, etc. are regulated.

Reflex signals are transmitted at high speed by nerve pathways that form reflex arcs. This is the path along which impulses are transmitted from receptors to the central parts of the nervous system and from them to the working organs. The reflex arc consists of 5 parts: 1 - receptor link (perceives irritation and converts it into impulses); 2 - sensitive (centripetal) link (transmits excitation to the central nervous system); 3 - central link (information is analyzed in it with the participation of plug-in neurons); 4 - motor (centrifugal) link (transmits guiding impulses to the working body); 5 - working link (with the participation of a muscle or gland a certain action occurs) (ill. 10).

The transfer of excitation from one neuron to another is carried out using synapses. This is a plot of con

tact of one neuron with another or with a working organ. Excitation in synapses is transmitted by special mediator substances. They are synthesized by the presynaptic membrane and accumulate in synaptic vesicles. When nerve impulses reach the synapse, the vesicles burst and transmitter molecules enter the synaptic cleft. The dendrite membrane, called the postsynaptic membrane, receives information and turns it into impulses. The excitation is transmitted further by the next neuron.

So, due to the electrical nature of nerve impulses and the presence of special pathways, the nervous system carries out reflex regulation very quickly and provides a specific effect on organs.

Why are the endocrine and immune systems regulatory?

The endocrine system is a collection of glands that provide humoral regulation of the functions of physiological systems. The highest department of endocrine regulation is the hypothalamus, which, together with the pituitary gland, controls the peripheral glands. The cells of the endocrine glands produce hormones and send them into the internal environment. Blood, and subsequently tissue fluid, delivers these chemical signals to cells. Hormones can slow down or speed up cell function. For example, the adrenal hormone adrenaline revives the heart, while acetylcholine slows it down. The influence of hormones on organs is a slower way of controlling functions than through the nervous system, but the influence can be general and long-term.

The immune system is a collection of organs that form special chemical compounds and cells to provide protective effects on cells, tissues and organs. The central organs of the immune system include the red bone marrow and thymus, and the peripheral organs include the tonsils, appendix, and lymph nodes. The central place among the cells of the immune system is occupied by various leukocytes, and among chemical compounds - antibodies produced in response to foreign protein compounds. Cells and substances of the immune system spread through internal fluids. And their effects, like hormones, are slow, long-lasting and general.

So, the endocrine and immune systems are regulatory systems and carry out humoral and immune regulation in the human body.

ACTIVITY

Learning to know

Independent work with the table

Compare the nervous, endocrine and immune regulatory systems, determine the similarities and differences between them.

Biology + Neurophysiology

Platon Grigorievich Kostyuk (1924-2010) is an outstanding Ukrainian neurophysiologist. The scientist was the first to construct and use microelectrode technology to study the organization of nerve centers, penetrated into a nerve cell, and recorded its signals. He studied how information is converted from electrical to molecular form in the nervous system. Platon Kostyuk proved that calcium ions play an important role in these processes. What is the role of calcium ions in the nervous regulation of the functions of the human body?

Biology + Psychology

Each person reacts to colors differently, depending on their temperament and health. Psychologists, based on their attitude to color, determine a person’s character, his inclinations, intelligence, and type of psyche. Thus, the red color strengthens memory, gives vigor and energy, stimulates the nervous system, and the purple color enhances creativity, has a calming effect on the nervous system, and increases muscle tone. Using your knowledge of regulatory systems, try to explain the mechanism by which color affects the human body.

RESULT

This is textbook material

Observing the work of your body, you noticed that after running your breathing and heart rate increases. After eating, the amount of glucose in the blood increases. However, after some time, these indicators supposedly themselves acquire their original values. How does this regulation occur?

Humoral regulation(Latin humor - liquid) is carried out with the help of substances that affect metabolic processes in cells, as well as the functioning of organs and the body as a whole. These substances enter the blood, and from it into the cells. Thus, increasing the level of carbon dioxide in the blood increases the breathing rate.

Some substances, such as hormones, perform their function even if their concentration in the blood is very low. Most hormones are synthesized and released into the blood by cells of the endocrine glands, which form the endocrine system. Traveling with the blood throughout the body, hormones can enter any organ. But a hormone affects the functioning of an organ only if the cells of that organ have receptors specifically for this hormone. The receptors combine with hormones, and this entails a change in cell activity. Thus, the hormone insulin, attaching to liver cell receptors, stimulates the penetration of glucose into it and the synthesis of glycogen from this compound.

Endocrine system ensures the growth and development of the body, its individual parts and organs with the help of hormones. It is involved in the regulation of metabolism and adapts it to the body's constantly changing needs.

Nervous regulation. Unlike the humoral regulation system, which responds primarily to changes in the internal environment, the nervous system responds to events occurring both inside the body and outside it. With the help of the nervous system, the body responds to any influence very quickly. Such reactions to stimuli are called reflexes.

Immune regulation is provided by the immune system, the task of which is to create immunity - the body’s ability to resist the action of external and internal enemies. They are bacteria, viruses, various substances that disrupt the normal functioning of the body, as well as its cells that have died or degenerated. The main fighting forces of the immune regulation system are certain blood cells and special substances contained in it.

Human organism- self-regulating system. The task of self-regulation is to support all chemical, physical and biological indicators of the body’s functioning within certain limits. Thus, the body temperature of a healthy person can fluctuate between 36-37 ° C, blood pressure 115/75-125/90 mm Hg. Art., blood glucose concentration - 3.8-6.1 mmol / l. The state of the body in which all parameters of its functioning remain relatively constant is called homeostasis (Greek homeo - similar, stasis - state). The work of the body's regulatory systems, operating in constant interconnection, is aimed at maintaining homeostasis.

Relationship between the nervous, humoral and immune regulatory systems

The vital functions of the body are regulated, acting in concert, by the nervous, humoral and immune systems. These systems complement each other, forming a single mechanism of neurohumoral-immune regulation.

Neurohumoral interactions. Any complex action of the body on an external stimulus - be it tasks in a test or meeting an unfamiliar dog in the yard of your house - begins with the regulatory influences of the central nervous system.

Excitation of the reticular formation brings all structures of the central nervous system into a state of readiness for action. Activation of the limbic system awakens a specific emotion—surprise, joy, anxiety, or fear—depending on how the stimulus is assessed. At the same time, the hypothalamus is activated and hypothalamic-pituitary system. Under their influence, the sympathetic nervous system changes the mode of operation of internal organs, the adrenal medulla and thyroid glands increase the secretion of hormones. The production of glucose by the liver increases, and the level of energy metabolism in cells increases. There is a mobilization of the body's internal resources necessary to effectively respond to the stimulus acting on the body.

Activity of the nervous system may be subject to humoral influences. In this case, information about changes in the state of the body is transmitted to the structures of the nervous system with the help of humoral factors. It, in turn, stimulates reactions aimed at restoring homeostasis.

Everyone has felt hunger and knows how a person acts when he wants to eat. How does the feeling of hunger arise and is it a manifestation of food motivation? The centers of hunger and satiety are contained in the hypothalamus. When glucose concentrations decrease and insulin levels increase, neurons that are sensitive to their content in the blood are activated, and we feel that we are hungry. Information from the hypothalamus goes to the cerebral cortex. With its participation, eating behavior is formed, that is, a set of actions aimed at searching for and absorbing food.

The feeling of fullness occurs when the level of glucose and fatty acids in the blood increases, and the level of insulin decreases. All these signals activate the saturation center of the hypothalamus, food motivation disappears - eating behavior is inhibited.

Let us give another example of the relationship between the humoral and nervous regulation systems. With the onset of puberty, the body's production of sex hormones increases. Sex hormones influence the structures of the nervous system. The hypothalamus contains centers whose neurons are connected to the sex hormone testosterone and are responsible for sexual reflexes. As a result of the action of testosterone in women and men, sexual desire arises - one of the most important human motivations, without which the implementation of the reproductive function is impossible.

Neuroimmune interactions. The immune system, destroying foreign agents and damaged cells of the body itself, thereby regulates the state of its internal environment. There is a relationship between the immune system and the nervous system.

Lymphocytes that mature in the organs of the immune system have receptors for mediators of the sympathetic and parasympathetic nervous system. Consequently, these cells are able to perceive signals coming from the nerve centers and respond to them. The hypothalamus receives humoral signals about the penetration of antigen into the body and activates the autonomic nervous system. Impulses pass through sympathetic neurons innervating the lymphoid tissues of the immune system, and the mediator norepinephrine is released. Under its influence, the number of T-lymphocytes increases, which inhibit the activity of B-lymphocytes. Parasympathetic neurons, when excited, release the mediator acetylcholine, which accelerates the maturation of B lymphocytes. So, the sympathetic nervous system is capable of suppressing the immune response, and the parasympathetic nervous system is capable of stimulating it.

Homework

2. Prepare for the test “Nervous System”.

Depending on the nature of the innervation of organs and tissues, the nervous system is divided into somatic And vegetative. The somatic nervous system regulates voluntary movements of skeletal muscles and provides sensation. The autonomic nervous system coordinates the activity of internal organs, glands, and the cardiovascular system and innervates all metabolic processes in the human body. The work of this regulatory system is not controlled by consciousness and is carried out thanks to the coordinated work of its two departments: sympathetic and parasympathetic. In most cases, activation of these departments has the opposite effect. The sympathetic influence is most pronounced when the body is under stress or intense work. The sympathetic nervous system is a system of alarm and mobilization of reserves necessary to protect the body from environmental influences. It sends signals that activate brain activity and mobilize protective reactions (thermoregulation process, immune reactions, blood clotting mechanisms). When the sympathetic nervous system is activated, the heart rate increases, digestion processes slow down, the respiratory rate increases and gas exchange increases, the concentration of glucose and fatty acids in the blood increases due to their release by the liver and adipose tissue (Fig. 5).

The parasympathetic division of the autonomic nervous system regulates the functioning of internal organs in a state of rest, i.e. This is a system of ongoing regulation of physiological processes in the body. The predominance of activity of the parasympathetic part of the autonomic nervous system creates conditions for rest and restoration of body functions. When it is activated, the frequency and strength of heart contractions decreases, digestion processes are stimulated, and the lumen of the respiratory tract decreases (Fig. 5). All internal organs are innervated by both the sympathetic and parasympathetic divisions of the autonomic nervous system. The skin and musculoskeletal system have only sympathetic innervation.

Fig.5. Regulation of various physiological processes of the human body under the influence of the sympathetic and parasympathetic divisions of the autonomic nervous system

The autonomic nervous system has a sensory (sensitive) component, represented by receptors (sensitive devices) located in the internal organs. These receptors perceive indicators of the state of the internal environment of the body (for example, the concentration of carbon dioxide, pressure, the concentration of nutrients in the bloodstream) and transmit this information along centripetal nerve fibers to the central nervous system, where this information is processed. In response to information received from the central nervous system, signals are transmitted through centrifugal nerve fibers to the corresponding working organs involved in maintaining homeostasis.

The endocrine system also regulates the activity of tissues and internal organs. This regulation is called humoral and is carried out with the help of special substances (hormones) that are secreted by endocrine glands into the blood or tissue fluid. Hormones – These are special regulatory substances produced in some tissues of the body, transported through the bloodstream to various organs and affecting their functioning. While the signals that provide nervous regulation (nerve impulses) travel at high speed and require fractions of a second to respond from the autonomic nervous system, humoral regulation occurs much more slowly, and under its control are those processes in our body that require minutes to regulate and a watch. Hormones are powerful substances and produce their effects in very small quantities. Each hormone affects specific organs and organ systems called target organs. Cells of target organs have specific receptor proteins that selectively interact with specific hormones. The formation of a complex of a hormone with a receptor protein includes a whole chain of biochemical reactions that determine the physiological effect of this hormone. The concentration of most hormones can vary within wide limits, which ensures the maintenance of the constancy of many physiological parameters with the continuously changing needs of the human body. Nervous and humoral regulation in the body are closely interconnected and coordinated, which ensures its adaptability in a constantly changing environment.

Hormones play a leading role in the humoral functional regulation of the human body. pituitary gland and hypothalamus. The pituitary gland (lower cerebral appendage) is a part of the brain belonging to the diencephalon, it is attached by a special leg to another part of the diencephalon, hypothalamus, and is in close functional connection with it. The pituitary gland consists of three parts: anterior, middle and posterior (Fig. 6). The hypothalamus is the main regulatory center of the autonomic nervous system; in addition, this part of the brain contains special neurosecretory cells that combine the properties of a nerve cell (neuron) and a secretory cell that synthesizes hormones. However, in the hypothalamus itself, these hormones are not released into the blood, but enter the pituitary gland, into its posterior lobe ( neurohypophysis), where they are released into the blood. One of these hormones antidiuretic hormone(ADH or vasopressin), mainly affects the kidney and the walls of blood vessels. An increase in the synthesis of this hormone occurs with significant blood loss and other cases of fluid loss. Under the influence of this hormone, the loss of fluid by the body is reduced; in addition, like other hormones, ADH also affects brain functions. It is a natural stimulant of learning and memory. Lack of synthesis of this hormone in the body leads to a disease called diabetes insipidus, in which the volume of urine excreted by patients sharply increases (up to 20 liters per day). Another hormone released into the blood by the posterior pituitary gland is called oxytocin. The targets for this hormone are the smooth muscles of the uterus, muscle cells surrounding the ducts of the mammary glands and testes. An increase in the synthesis of this hormone is observed at the end of pregnancy and is absolutely necessary for labor to proceed. Oxytocin impairs learning and memory. Anterior pituitary gland ( adenohypophysis) is an endocrine gland and secretes a number of hormones into the blood that regulate the functions of other endocrine glands (thyroid, adrenal glands, gonads) and are called tropic hormones. For example, adenocorticotropic hormone (ACTH) affects the adrenal cortex and under its influence a number of steroid hormones are released into the blood. Thyroid-stimulating hormone stimulates the thyroid gland. Somatotropic hormone(or growth hormone) affects bones, muscles, tendons, and internal organs, stimulating their growth. In the neurosecretory cells of the hypothalamus, special factors are synthesized that influence the functioning of the anterior pituitary gland. Some of these factors are called liberins, they stimulate the secretion of hormones by the cells of the adenohypophysis. Other factors statins, inhibit the secretion of corresponding hormones. The activity of neurosecretory cells of the hypothalamus changes under the influence of nerve impulses coming from peripheral receptors and other parts of the brain. Thus, the connection between the nervous and humoral systems is primarily carried out at the level of the hypothalamus.

Fig.6. Diagram of the brain (a), hypothalamus and pituitary gland (b):

1 – hypothalamus, 2 – pituitary gland; 3 – medulla oblongata; 4 and 5 – neurosecretory cells of the hypothalamus; 6 – pituitary stalk; 7 and 12 – processes (axons) of neurosecretory cells;
8 – posterior lobe of the pituitary gland (neurohypophysis), 9 – intermediate lobe of the pituitary gland, 10 – anterior lobe of the pituitary gland (adenohypophysis), 11 – median eminence of the pituitary stalk.

In addition to the hypothalamic-pituitary system, the endocrine glands include the thyroid and parathyroid glands, the adrenal cortex and medulla, islet cells of the pancreas, secretory cells of the intestine, gonads, and some heart cells.

Thyroid– this is the only human organ that is capable of actively absorbing iodine and incorporating it into biologically active molecules, thyroid hormones. These hormones affect almost all cells of the human body; their main effects are related to the regulation of growth and development processes, as well as metabolic processes in the body. Thyroid hormones stimulate the growth and development of all body systems, especially the nervous system. When the thyroid gland is not functioning properly in adults, a disease called myxedema. Its symptoms are a decrease in metabolism and dysfunction of the nervous system: the reaction to stimuli slows down, fatigue increases, body temperature drops, edema develops, the gastrointestinal tract suffers, etc. A decrease in thyroid levels in newborns is accompanied by more severe consequences and leads to cretinism, mental retardation up to complete idiocy. Previously, myxedema and cretinism were common in mountainous areas where glacial water is low in iodine. Now this problem is easily solved by adding sodium iodine salt to table salt. Increased functioning of the thyroid gland leads to a disorder called Graves' disease. In such patients, the basal metabolism increases, sleep is disturbed, the temperature rises, breathing and heart rate increase. Many patients develop bulging eyes, and sometimes a goiter forms.

Adrenal glands- paired glands located at the poles of the kidneys. Each adrenal gland has two layers: the cortex and the medulla. These layers are completely different in their origin. The outer cortical layer develops from the middle germ layer (mesoderm), the medulla is a modified unit of the autonomic nervous system. The adrenal cortex produces corticosteroid hormones (corticoids). These hormones have a wide spectrum of action: they affect water-salt metabolism, fat and carbohydrate metabolism, the immune properties of the body, and suppress inflammatory reactions. One of the main corticoids, cortisol, is necessary to create a reaction to strong stimuli that lead to the development of stress. Stress can be defined as a threatening situation that develops under the influence of pain, blood loss, and fear. Cortisol prevents blood loss, constricts small arterial vessels, and enhances the contractility of the heart muscle. When the cells of the adrenal cortex are destroyed, it develops Addison's disease. Patients experience a bronze tint to the skin in some parts of the body, develop muscle weakness, weight loss, and suffer from memory and mental abilities. Previously, the most common cause of Addison's disease was tuberculosis, now it is autoimmune reactions (erroneous production of antibodies to one's own molecules).

Hormones are synthesized in the adrenal medulla: adrenalin And norepinephrine. The targets of these hormones are all tissues of the body. Adrenaline and norepinephrine are designed to mobilize all a person’s strength in the event of a situation requiring great physical or mental stress, in case of injury, infection, or fear. Under their influence, the frequency and strength of heart contractions increases, blood pressure rises, breathing quickens and the bronchi dilate, and the excitability of brain structures increases.

Pancreas It is a mixed type gland; it performs both digestive (production of pancryotic juice) and endocrine functions. It produces hormones that regulate carbohydrate metabolism in the body. Hormone insulin stimulates the flow of glucose and amino acids from the blood into the cells of various tissues, as well as the formation in the liver from glucose of the main reserve polysaccharide of our body, glycogen. Another pancreatic hormone glucagon, in its biological effects, is an insulin antagonist, increasing blood glucose levels. Glucagon stimulates the breakdown of glycogen in the liver. With a lack of insulin, it develops diabetes, Glucose received from food is not absorbed by the tissues, accumulates in the blood and is excreted from the body in the urine, while the tissues are sorely lacking glucose. Nervous tissue is especially severely affected: the sensitivity of peripheral nerves is impaired, a feeling of heaviness in the limbs occurs, and convulsions are possible. In severe cases, diabetic coma and death may occur.

The nervous and humoral systems, working together, excite or inhibit various physiological functions, which minimizes deviations of individual parameters of the internal environment. The relative constancy of the internal environment in humans is ensured by regulating the activity of the cardiovascular, respiratory, digestive, excretory systems, and sweat glands. Regulatory mechanisms ensure the constancy of the chemical composition, osmotic pressure, number of blood cells, etc. Very advanced mechanisms ensure the maintenance of a constant human body temperature (thermoregulation).

1. Deviation regulation - a cyclic mechanism in which any deviation from the optimal level of a regulated indicator mobilizes all the apparatus of the functional system to restore it to the previous level. Regulation by deviation assumes the presence of a channel as part of the system complex negative feedback, providing multidirectional influence: strengthening incentive management mechanisms in case of weakening process indicators or weakening incentive mechanisms in case of excessive strengthening of process indicators. For example, when blood pressure increases, regulatory mechanisms are activated to ensure a decrease in blood pressure, and when blood pressure is low, the opposite reactions are activated. Unlike negative feedback, positive

Feedback, rarely found in the body, it has only a unidirectional, enhancing effect on the development of the process under the control of the control complex. Therefore, positive feedback makes the system unstable, unable to ensure the stability of the regulated process within the physiological optimum. For example, if blood pressure were regulated according to the principle of positive feedback, in the case of a decrease in blood pressure, the action of regulatory mechanisms would lead to an even greater decrease, and in the case of an increase, to an even greater increase. An example of positive feedback is the strengthening of the secretion of digestive juices in the stomach after eating, which is carried out with the help of hydrolysis products absorbed into the blood.

2. Advance regulation lies in the fact that regulatory mechanisms are activated before a real change in the parameter of the regulated process (indicator) based on information entering the nerve center of the functional system and signaling a possible change in the regulated process in the future. For example, thermoreceptors (temperature detectors) located inside the body provide control over the temperature of internal areas of the body. Skin thermoreceptors mainly play the role of ambient temperature detectors. With significant deviations in ambient temperature, the prerequisites for a possible change in the temperature of the internal environment of the body are created. However, normally this does not happen, since impulses from skin thermoreceptors, continuously entering the hypothalamic thermoregulatory center, allow it to make changes in the functioning of the system’s effectors until there is a real change in the temperature of the internal environment of the body. Increased ventilation of the lungs during physical activity begins before the increase in oxygen consumption and the accumulation of carbonic acid in the human blood. This is accomplished due to afferent impulses from proprioceptors of actively working muscles. Consequently, the impulse of proprioceptors acts as a factor organizing the restructuring of the functioning of the functional system, which maintains the optimal level of P02, Pcc, 2 and pH of the internal environment for metabolism in advance.

Anticipatory regulation can be implemented using the mechanism conditioned reflex. It is shown that conductors of freight trains in winter sharply increase heat production as they move away from the departure station, where the conductor was in a warm room. On the way back, as we get closer

to the station, heat production in the body is clearly reduced, although in both cases the conductor was subjected to equally intense cooling, and all the physical conditions for heat release did not change (A. D. Slonim).

Thanks to the dynamic organization of regulatory mechanisms, functional systems ensure exceptional stability of the body's metabolic reactions, both at rest and in a state of increased activity in the environment.