The relationship of the nervous and endocrine systems. Relationship between the endocrine and nervous systems. "Orenburg State Agrarian University"
Based on a huge amount of factual material, today we can talk about the existence of a single regulatory system of the body, uniting the nervous, immune and endocrine systems (Fig. 17).
According to some scientists, immunity is a disseminated mobile brain.
The immune system, like the central nervous system, is capable of recognizing, remembering and retrieving information from memory. The carriers of neurological memory functions are the neurons of the analyzer and limbic systems of the brain. The carrier of the function of immunological memory are certain subpopulations of T- and B-lymphocytes, called memory lymphocytes.
The immune system recognizes external and internal antigenic signals of a different nature, remembers and transmits information through
Rice. 17. Neuroimmunohormonal interactions (according to Play fair, 1998 in our modification)
blood flow via cytokines to the central nervous system. The latter, in turn, having processed the signal, has a regulatory effect on the immune system with the help of neuropeptides and hormones of the hypothalamic-pituitary-adrenal axis.
Currently, the mechanisms of neuroimmune interactions at the level of the receptor apparatus of cell membranes have been discovered. On the membranes of lymphocytes, receptors for mediators - beta-en-
dorphin, methenkephalin, protein P, adrenergic substances. It has been established that immunocompetent cells are able to produce corticotropin, endorphin, enkephalin. The possibility of action of immune mediators - interleukins (IL-1, IL-2 and IL-6), interferons, tumor necrosis factor (TNF) - on neuroglial cells and neurons has been proven. Under the influence of IL-1 and TNF, the secretion of corticotropin by the pituitary cells increases. In turn, neurons are capable of producing IL-2 and IL-6 (see Fig. 17).
It has been established that the membranes of neurons and lymphocytes are equipped with the same receptors for corticotropin, vasopressin and beta-endorphin. It is postulated that in this way, with the help of common cellular receptors and soluble hormones, neutropeptides and cytokines, the immune and central nervous systems exchange information with each other.
It has been proven that in the syndrome of hyperproduction of cytokines, excessive secretion of IL-1, interferon and TNF by macrophages is the cause of depressive states, which is accompanied by muscle weakness, prolonged subfebrile condition, pancytopenia, hepatosplenomegaly. This is supported by the following arguments: 1) the development of depression in people who therapeutic purpose inject cytokines; 2) change under the influence of IL-1 hormonal status, leading to depression; 3) frequent association with depression of diseases accompanied by activation of macrophages (ischemia, rheumatoid arthritis, etc.);
- a greater frequency of depression in women due to the fact that estrogens increase the secretion of IL-1 by macrophages.
It is known that the membrane of T-lymphocytes and neurons has a common Tx-1 antigen, which once again testifies in favor of the commonality of these systems. Interesting experiments have been carried out. Chickens were conditioned-reflex trained not to peck at red granules. After that, the trained birds were injected with monoclonal antibodies to the Tx-1 antigen of T-lymphocytes. As a result, the chickens developed amnesia, strictly dependent on the dose of antibodies. The birds began to peck at the granules of all colors. The authors concluded that T-lymphocytes are involved in the process of memory formation.
The idea of the inseparable unity of the nervous, endocrine and immune systems, as well as neurological and immunological memory, was strengthened by data on the wide distribution of neuropeptides outside the brain. Currently, more than 20 neuropeptites identified in the blood and lymph have already been described. Among them are neurotensin, vasoactive intestinal neuropeptide (substance P), peptide-delta sleep, enkephalins, endorphins (endogenous opioids), etc. It is believed that neuropeptides play an important role in the integrative activity of the nervous, endocrine and immune systems due to the presence on their cells identical receptors through which the relationship is carried out.
Modern life characterized by stress and global environmental pollution, which, affecting the psychoneuroimmunoendocrine system, lead to the development of secondary immunodeficiency and neuropsychiatric disorders.
From among the numerous definitions of the concept of "stress" we give the formulation of G. N. Kassil (1983): stress is "a general adaptive reaction of the body that develops in response to the threat of homeostasis disturbance".
In accordance with the causes, there is the following classification of types of stress: 1) emotional; 2) social; 3) production; 4) academic; 5) sports; 6) hypokinetic; 7) reproductive; 8) vaccinal; 9) medicinal; 10) infectious;
11) space; 12) food; 13) transport; 14) hypoxic; 15) painful; 16) temperature; 17) light; 18) noise;
19) olfactory; 20) stress of pathological processes; 21) ecological. Undoubtedly, this list can be continued.
A great contribution to understanding the mechanisms of development of secondary immunodeficiency under the influence of extreme emotional and physical factors made the discovery of B. B. Pershin et al. They established the fact of the disappearance of immunoglobulins of all classes in the peripheral blood of athletes at the peak of sports form before important competitions. Subsequently, these data were confirmed on students during the exams.
Neurons are the building blocks for the human "message system", there are entire networks of neurons that transmit signals between the brain and body. These organized networks, which include more than a trillion neurons, create the so-called nervous system. It consists of two parts: central nervous systems s (brain and spinal cord) and peripheral (nerves and nerve networks throughout the body)
Endocrine system part of the body's information transmission system. Uses glands throughout the body that regulate many processes such as metabolism, digestion, blood pressure, and growth. Among the most important endocrine glands are the pineal gland, hypothalamus, pituitary gland, thyroid gland, ovaries and testicles.
central nervous system(CNS) consists of the brain and spinal cord.
Peripheral nervous system(PNS) consists of nerves that extend beyond the central nervous system. The PNS can be further divided into two different nervous systems: somatic and vegetative.
somatic nervous system: The somatic nervous system transmits physical sensations and commands to movements and actions.
autonomic nervous system: The autonomic nervous system controls involuntary functions such as heartbeat, respiration, digestion and blood pressure. This system is also associated with emotional responses such as sweating and crying.
10. Lower and higher nervous activity.
Inferior nervous activity(NND) - directed to the internal environment of the body. This is a set of neurophysiological processes that ensure the implementation of unconditioned reflexes and instincts. This is the activity of the Spinal Cord and the brain stem, which ensures the regulation of activity internal organs and their interconnection, thanks to which the organism functions as a whole.
Higher nervous activity (HNI) - directed towards the external environment. This is a set of neurophysiological processes that provide conscious and subconscious processing of information, assimilation of information, adaptive behavior to the environment and ontogeny training in all types of activities, including purposeful behavior in society.
11. Physiology of adaptation and stress.
Adaptation Syndrome:
The first is called the anxiety stage. This stage is associated with the mobilization of the body's defense mechanisms, an increase in the level of adrenaline in the blood.
The next stage is called the stage of resistance or resistance. This stage is distinguished by the highest level of body resistance to the action of harmful factors, which reflects the ability to maintain the state of homeostasis.
If the impact of the stressor continues, then as a result, the "energy of adaptation", i.e. the adaptive mechanisms involved in maintaining the resistance stage will exhaust themselves. Then the organism enters the final stage - the stage of exhaustion, when the survival of the organism may be threatened.
The human body deals with stress in the following ways:
1. Stressors are analyzed in the higher parts of the cerebral cortex, after which certain signals are sent to the muscles responsible for movement, preparing the body to respond to the stressor.
2. The stressor also affects the autonomic nervous system. The pulse quickens, blood pressure rises, the level of erythrocytes and blood sugar rises, breathing becomes frequent and intermittent. This increases the amount of oxygen supplied to the tissues. The person is ready to fight or flee.
3. From the analyzer sections of the cortex, signals enter the hypothalamus and adrenal glands. The adrenal glands regulate the release of adrenaline into the blood, which is a common fast-acting stimulant.
Our body can be compared to a metropolis. The cells that inhabit it sometimes live in “families”, forming organs, and sometimes, lost among others, they become hermits (like, for example, the cells of the immune system). Some are homebodies and never leave their haven, others are travelers and do not sit in one place. All of them are different, each with its own needs, character and regime. Between the cells are small and large transport highways - blood and lymphatic vessels. Every second, millions of events occur in our body: someone or something disrupts the peaceful life of cells, or some of them forget about their duties or, on the contrary, are too zealous. And, as in any metropolis, competent administration is required to maintain order. We know that our main manager is the nervous system. And her right hand is the endocrine system (ES).
In order
ES is one of the most complex and mysterious systems of the body. Complex because it consists of many glands, each of which can produce from one to dozens of different hormones, and regulates the work of a huge number of organs, including the endocrine glands themselves. Within the system, there is a special hierarchy that allows you to strictly control its work. The mystery of ES is associated with the complexity of the mechanisms of regulation and composition of hormones. Cutting-edge technology is required to research her work. The role of many hormones is still unclear. And we only guess about the existence of some, moreover, it is still impossible to determine their composition and the cells that secrete them. That is why endocrinology - the science that studies hormones and the organs that produce them - is considered one of the most difficult among medical specialties and the most promising. Having understood the exact purpose and mechanisms of work of certain substances, we will be able to influence the processes occurring in our body. Indeed, thanks to hormones, we are born, it is they who create a feeling of attraction between future parents, determine the time of formation of germ cells and the moment of fertilization. They change our lives, affecting mood and character. Today we know that aging processes are also under the jurisdiction of the ES.
Characters...
The organs that make up the ES (thyroid gland, adrenal glands, etc.) are groups of cells located in other organs or tissues, and individual cells scattered in different places. The difference between the endocrine glands and others (they are called exocrine) is that the former secrete their products - hormones - directly into the blood or lymph. For this they are called endocrine glands. And exocrine - into the lumen of one or another organ (for example, the largest exocrine gland - the liver - secretes its secret - bile - into the lumen of the gallbladder and further into the intestine) or out (for example, the lacrimal glands). Exocrine glands are called glands of external secretion. Hormones are substances that can act on cells that are sensitive to them (they are called target cells), changing the rate of metabolic processes. The release of hormones directly into the blood gives ES a huge advantage. It takes a matter of seconds to achieve the effect. Hormones enter directly into the bloodstream, which serves as a transport and allows you to very quickly deliver the right substance to all tissues, in contrast to the nerve signal that propagates along the nerve fibers and, due to their rupture or damage, may not reach its goal. In the case of hormones, this will not happen: liquid blood easily finds workarounds if one or more vessels are blocked. In order for the organs and cells to which the ES message is intended to receive it, they have receptors that perceive a particular hormone. A feature of the endocrine system is its ability to "feel" the concentration of various hormones and adjust it. And their number depends on age, gender, time of day and year, age, mental and physical state of a person, and even our habits. So ES sets the rhythm and speed for our metabolic processes.
...and performers
The pituitary gland is the main endocrine organ. It secretes hormones that stimulate or inhibit the work of others. But the pituitary gland is not the pinnacle of ES, it only plays the role of a manager. The hypothalamus is the superior authority. This is a part of the brain, consisting of clusters of cells that combine the properties of the nervous and endocrine. They secrete substances that regulate the work of the pituitary and endocrine glands. Under the guidance of the hypothalamus, the pituitary gland produces hormones that affect tissues that are sensitive to them. So, thyroid-stimulating hormone regulates the functioning of the thyroid gland, corticotropic - the work of the adrenal cortex. Somatotropic hormone (or growth hormone) does not affect any specific organ. Its action extends to many tissues and organs. This difference in the action of hormones is caused by the difference in their significance for the body and the number of tasks that they provide. A feature of this complex system is the principle of feedback. The EU can be called without exaggeration the most democratic. And, although it has “leading” organs (the hypothalamus and pituitary gland), the subordinate ones also affect the work of the higher glands. In the hypothalamus, the pituitary gland has receptors that respond to the concentration of various hormones in the blood. If it is high, signals from the receptors will block their production" at all levels. This is the feedback principle in action. The thyroid gland got its name from its shape. It closes the neck, surrounding the trachea. Its hormones include iodine, and its lack can Gland hormones provide a balance between the formation of adipose tissue and the use of stored fats in it. They are necessary for the development of the skeleton and the well-being of bone tissue, and also enhance the action of other hormones (for example, insulin, accelerating the metabolism of carbohydrates). These substances play a critical role in the development of the nervous system.Lack of thyroid hormones in babies leads to underdevelopment of the brain, and later - to a decrease in intelligence.Therefore, all newborns are examined for the level of these substances (such a test is included in the newborn screening program).Together with adrenaline, thyroid hormones glands affect the functioning of the heart and regulate blood pressure.
parathyroid glands
parathyroid glands- these are 4 glands located in the thickness of fatty tissue behind the thyroid, for which they got their name. The glands produce 2 hormones: parathyroid and calcitonin. Both provide the exchange of calcium and phosphorus in the body. Unlike most endocrine glands, the work of the parathyroid glands is regulated by fluctuations mineral composition blood and vitamin D. The pancreas controls the metabolism of carbohydrates in the body, and is also involved in digestion and produces enzymes that break down proteins, fats and carbohydrates. Therefore, it is located in the region of the transition of the stomach into the small intestine. The gland secretes 2 hormones: insulin and glucagon. The first lowers blood sugar levels, forcing cells to more actively absorb it and use it. The second, on the contrary, increases the amount of sugar, forcing the cells of the liver and muscle tissue to give it away. The most common disease associated with disorders in the pancreas is type 1 diabetes mellitus (or insulin-dependent). It develops due to the destruction of insulin-producing cells by cells of the immune system. In most children who are sick diabetes, there are features of the genome that probably predetermine the development of the disease. But most often it is triggered by an infection or stress. The adrenal glands get their name from their location. A person cannot live without the adrenal glands and the hormones they produce, and these organs are considered vital. The program of examination of all newborns includes a test for violations of their work - the consequences of such problems will be so dangerous. The adrenal glands produce a record number of hormones. The most famous of them is adrenaline. It helps the body prepare and cope with possible dangers. This hormone makes the heart beat faster and pump more blood to the organs of movement (if you need to flee), increases the frequency of breathing to provide the body with oxygen, reduces sensitivity to pain. It increases blood pressure, providing maximum blood flow to the brain and other important organs. Noradrenaline has a similar effect. The second most important adrenal hormone is cortisol. It is difficult to name any process in the body that it would not have an effect on. It causes tissues to release stored substances into the blood so that all cells are provided with nutrients. The role of cortisol increases with inflammation. It stimulates the production of protective substances and the work of the cells of the immune system necessary to fight inflammation, and if the latter are too active (including against their own cells), cortisol suppresses their zeal. Under stress, it blocks cell division so that the body does not waste energy on this work, but is busy restoring order. the immune system would not miss "defective" samples. The hormone aldosterone regulates the concentration in the body of the main mineral salts - sodium and potassium. The gonads are the testicles in boys and the ovaries in girls. The hormones that they produce are able to change metabolic processes. So, testosterone (the main male hormone) helps the growth of muscle tissue, the skeletal system. It increases appetite and makes boys more aggressive. And, although testosterone is considered a male hormone, it is also secreted by women, but at a lower concentration.
To the doctor!
Most often, children who are overweight and those babies who are seriously behind their peers in growth come to see a pediatric endocrinologist. Parents are more likely to pay attention to the fact that the child stands out among their peers, and begin to find out the reason. Most other endocrine diseases do not have characteristic features, and parents and doctors often learn about the problem when the violation has already seriously changed the work of some organ or the whole organism. Look at the baby: physique. In young children, the head and torso will be larger relative to the total body length. From 9-10 years old, the child begins to stretch, and the proportions of his body are approaching adults.
Bilateral action of the nervous and endocrine systems
Each human tissue and organ functions under the double control of the autonomic nervous system and humoral factors, in particular hormones. This dual control is the basis of the "reliability" of regulatory influences, whose task is to maintain a certain level of individual physical and chemical parameters of the internal environment.
These systems excite or inhibit various physiological functions in order to minimize deviations of these parameters despite significant fluctuations in the external environment. This activity is consistent with the activity of systems that ensure the interaction of the body with environmental conditions, which is constantly changing.
Human organs have a large number of receptors, the irritation of which causes various physiological reactions. At the same time, many nerve endings from the central nervous system approach the organs. This means that there is a two-way connection between human organs and the nervous system: they receive signals from the central nervous system and, in turn, are a source of reflexes that change the state of themselves and the body as a whole.
The endocrine glands and the hormones they produce are in close relationship with the nervous system, forming a common integral regulatory mechanism.
The connection of the endocrine glands with the nervous system is bidirectional: the glands are densely innervated from the side of the autonomic nervous system, and the secret of the glands through the blood acts on the nerve centers.
Remark 1
To maintain homeostasis and carry out basic life functions, two main systems have evolved: nervous and humoral, which work in concert.
Humoral regulation is carried out by the formation in the endocrine glands or groups of cells that perform an endocrine function (in the glands of mixed secretion), and the entry of biologically active substances - hormones into the circulating fluids. Hormones are characterized by a distant action and the ability to influence in very low concentrations.
The integration of nervous and humoral regulation in the body is especially pronounced during the action of stress factors.
The cells of the human body are combined into tissues, and those, in turn, into organ systems. In general, all this represents a single supersystem of the body. All the huge number of cellular elements in the absence of a complex regulatory mechanism in the body would not be able to function as a single whole.
The system of endocrine glands and the nervous system play a special role in regulation. It is the state of endocrine regulation that determines the nature of all processes occurring in the nervous system.
Example 1
Under the influence of androgens and estrogens, instinctive behavior, sexual instincts are formed. Obviously, the humoral system also controls neurons, as well as other cells in our body.
The evolutionary nervous system arose later than the endocrine system. These two regulatory systems complement each other, forming a single functional mechanism that provides highly effective neurohumoral regulation, putting it at the head of all systems that coordinate all the life processes of a multicellular organism.
This regulation of the constancy of the internal environment in the body, which occurs according to the feedback principle, cannot fulfill all the tasks of the body's adaptation, but is very effective in maintaining homeostasis.
Example 2
The adrenal cortex produces steroid hormones in response to emotional arousal, disease, hunger, etc.
A connection is needed between the nervous system and the endocrine glands so that the endocrine system can respond to emotions, light, smells, sounds, and so on.
Regulatory role of the hypothalamus
The regulatory influence of the central nervous system on the physiological activity of the glands is carried out through the hypothalamus.
The hypothalamus is afferently connected with other parts of the central nervous system, primarily with the spinal cord, medulla oblongata and midbrain, thalamus, basal ganglia (subcortical formations located in the white matter of the cerebral hemispheres), the hypocampus (the central structure of the limbic system), individual fields of the cerebral cortex and etc. Thanks to this, information from the whole organism enters the hypothalamus; signals from extero- and interoreceptors that enter the central nervous system through the hypothalamus are transmitted by the endocrine glands.
Thus, neurosecretory cells of the hypothalamus transform afferent nerve stimuli into humoral factors with physiological activity (in particular, releasing hormones).
The pituitary gland as a regulator of biological processes
The pituitary gland receives signals that inform about everything that happens in the body, but has no direct connection with the external environment. But in order for the vital activity of the organism not to be constantly disturbed by environmental factors, the organism must adapt to changing external conditions. The body learns about external influences by receiving information from the sense organs that transmit it to the central nervous system.
Acting as the supreme endocrine gland, the pituitary gland itself is controlled by the central nervous system and, in particular, the hypothalamus. This higher vegetative center is engaged in constant coordination and regulation of the activity of various parts of the brain and all internal organs.
Remark 2
The existence of the whole organism, the constancy of its internal environment is controlled precisely by the hypothalamus: the metabolism of proteins, carbohydrates, fats and mineral salts, the amount of water in tissues, vascular tone, heart rate, body temperature, etc.
A single neuroendocrine regulatory system in the body is formed as a result of the combination at the level of the hypothalamus of most of the humoral and nervous pathways of regulation.
Axons from neurons located in the cerebral cortex and subcortical ganglia approach the cells of the hypothalamus. They secrete neurotransmitters that both activate and inhibit the secretory activity of the hypothalamus. Nerve impulses coming from the brain, under the influence of the hypothalamus, are converted into endocrine stimuli, which, depending on the humoral signals coming to the hypothalamus from the glands and tissues, increase or decrease
The control of the hypothalamus of the pituitary gland occurs using both nerve connections and the system blood vessels. The blood entering the anterior pituitary gland necessarily passes through the median elevation of the hypothalamus, where it is enriched with hypothalamic neurohormones.
Remark 3
Neurohormones are peptide in nature and are parts of protein molecules.
In our time, seven neurohormones have been identified - liberins ("liberators") that stimulate the synthesis of tropic hormones in the pituitary gland. And three neurohormones, on the contrary, inhibit their production - melanostatin, prolactostatin and somatostatin.
Vasopressin and oxytocin are also neurohormones. Oxytocin stimulates the contraction of the smooth muscles of the uterus during childbirth, the production of milk by the mammary glands. With the active participation of vasopressin, the transport of water and salts through the cell membranes is regulated, the lumen of the vessels decreases (blood pressure rises). Because of its ability to retain water in the body, this hormone is often referred to as antidiuretic hormone (ADH). The main point of application of ADH is the renal tubules, where, under its influence, the reabsorption of water into the blood from the primary urine is stimulated.
The nerve cells of the nuclei of the hypothalamus produce neurohormones, and then transport them with their own axons to the posterior lobe of the pituitary gland, and from here these hormones are able to enter the bloodstream, causing a complex effect on the body's systems.
However, the pituitary and hypothalamus not only send orders through hormones, but they themselves are able to accurately analyze the signals that come from the peripheral endocrine glands. The endocrine system operates on the principle of feedback. If the endocrine gland produces an excess of hormones, then the secretion of a specific hormone by the pituitary gland slows down, and if the hormone is not produced enough, then the production of the corresponding pituitary tropic hormone increases.
Remark 4
In the process of evolutionary development, the mechanism of interaction between the hormones of the hypothalamus, the hormones of the pituitary gland and the endocrine glands has been worked out quite reliably. But if at least one link of this complex chain fails, there will immediately be a violation of the ratios (quantitative and qualitative) in the entire system, carrying various endocrine diseases.
The endocrine system, together with the nervous system, have a regulatory effect on all other organs and systems of the body, forcing it to function as a single system.
The endocrine system includes glands that do not have excretory ducts, but release highly active biological substances into the internal environment of the body, acting on cells, tissues and organs of substances (hormones), stimulating or weakening their functions.
Cells in which the production of hormones becomes the main or predominant function are called endocrine. In the human body, the endocrine system is represented by the secretory nuclei of the hypothalamus, pituitary, epiphysis, thyroid, parathyroid glands, adrenal glands, endocrine parts of the sex and pancreas, as well as individual glandular cells scattered in other (non-endocrine) organs or tissues.
With the help of hormones secreted by the endocrine system, the body functions are regulated and coordinated and brought into line with its needs, as well as with irritations received from the external and internal environment.
By chemical nature, most hormones belong to proteins - proteins or glycoproteins. Other hormones are derivatives of amino acids (tyrosine) or steroids. Many hormones, entering the bloodstream, bind to serum proteins and are transported throughout the body in the form of such complexes. The connection of the hormone with the carrier protein, although it protects the hormone from premature degradation, but weakens its activity. The release of the hormone from the carrier occurs in the cells of the organ that perceives this hormone.
Since hormones are released into the blood stream, a plentiful blood supply to the endocrine glands is an indispensable condition for their functioning. Each hormone acts only on those target cells that have specific chemical receptors in their plasma membranes.
The target organs, usually classified as non-endocrine, include the kidney, in the juxtaglomerular complex of which renin is produced; salivary and prostate glands, in which special cells are found that produce a factor that stimulates the growth of nerves; as well as special cells (enterinocytes) localized in the mucous membrane of the gastrointestinal tract and producing a number of enteric (intestinal) hormones. Many hormones (including endorphins and enkephalins), which have a wide spectrum of action, are produced in the brain.
Relationship between the nervous and endocrine systems
The nervous system, sending its efferent impulses along the nerve fibers directly to the innervated organ, causes directed local reactions that come on quickly and stop just as quickly.
Distant hormonal influences play a predominant role in the regulation of such general body functions as metabolism, somatic growth, and reproductive functions. The joint participation of the nervous and endocrine systems in ensuring the regulation and coordination of body functions is determined by the fact that the regulatory influences exerted by both the nervous and endocrine systems are implemented by fundamentally the same mechanisms.
At the same time, all nerve cells exhibit the ability to synthesize protein substances, as evidenced by the strong development of the granular endoplasmic reticulum and the abundance of ribonucleoproteins in their perikarya. The axons of such neurons, as a rule, end in capillaries, and the synthesized products accumulated in the terminals are released into the blood, with the current of which they are carried throughout the body and, unlike mediators, have not a local, but a distant regulatory effect, similar to the hormones of the endocrine glands. Such nerve cells are called neurosecretory, and the products produced and secreted by them are called neurohormones. Neurosecretory cells, perceiving, like any neurocyte, afferent signals from other parts of the nervous system, send their efferent impulses through the blood, that is, humorally (like endocrine cells). Therefore, neurosecretory cells, physiologically occupying an intermediate position between nervous and endocrine cells, unite the nervous and endocrine systems into a single neuroendocrine system and thus act as neuroendocrine transmitters (switches).
V last years it was found that the nervous system contains peptidergic neurons, which, in addition to mediators, secrete a number of hormones that can modulate the secretory activity of the endocrine glands. Therefore, as noted above, the nervous and endocrine systems act as a single regulatory neuroendocrine system.
Classification of the endocrine glands
At the beginning of the development of endocrinology as a science, endocrine glands were tried to be grouped according to their origin from one or another embryonic rudiment of the germ layers. However, further expansion of knowledge about the role of endocrine functions in the body showed that the commonality or proximity of embryonic anlages does not at all prejudge the joint participation of the glands developing from such rudiments in the regulation of body functions.
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