The nervous and endocrine systems are the main regulatory systems of the human body. Communication between the endocrine and nervous systems "Orenburg State Agrarian University"

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).

IN 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 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.

According to modern concepts, the following groups of endocrine glands are distinguished in the endocrine system: neuroendocrine transmitters (secretory nuclei of the hypothalamus, pineal gland), which, with the help of their hormones, switch information entering the central nervous system to the central link in the regulation of the adenohypophysis-dependent glands (adenohypophysis) and the neurohemal organ (posterior pituitary, or neurohypophysis). The adenohypophysis, thanks to the hormones of the hypothalamus (liberins and statins), secretes an adequate amount of tropic hormones that stimulate the function of the adenohypophysis-dependent glands (adrenal cortex, thyroid and gonads). The relationship between the adenohypophysis and the endocrine glands dependent on it is carried out according to the feedback principle (or plus or minus). The neurohemal organ does not produce its own hormones, but accumulates the hormones of the large cell nuclei of the hypothalamus (oxytocin, ADH-vasopressin), then releases them into the bloodstream and thus regulates the activity of the so-called target organs (uterus, kidneys). Functionally, the neurosecretory nuclei, the pineal gland, the adenohypophysis, and the neurohemal organ constitute the central link of the endocrine system, while the endocrine cells of non-endocrine organs ( digestive system, airways and lungs, kidneys and urinary tract, thymus), adenohypophysis-dependent glands (thyroid, adrenal cortex, gonads) and adenohypophysis-independent glands (parathyroid glands, adrenal medulla) are peripheral endocrine glands (or target glands).

Summarizing all of the above, we can say that the endocrine system is represented by the following main structural components.

1. Central regulatory formations of the endocrine system:

1) hypothalamus (neurosecretory nuclei);

2) pituitary gland;

3) epiphysis.

2. Peripheral endocrine glands:

1) thyroid gland;

2) parathyroid glands;

3) adrenal glands:

a) cortical substance;

b) the adrenal medulla.

3. Organs that combine endocrine and non-endocrine functions:

1) gonads:

a) testis;

b) ovary;

2) placenta;

3) pancreas.

4. Single hormone-producing cells:

1) neuroendocrine cells of the POPA group (APUD) (nervous origin);

2) single hormone-producing cells (not of nervous origin).

Last update: 30/09/2013

Description of the structure and functions of the nervous and endocrine systems, the principle of operation, their significance and role in the body.

While these are the building blocks for the human "message system", there are entire networks of neurons that relay 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: the central nervous system (the brain and spinal cord) and the peripheral (nerves and nerve networks throughout the body)

The endocrine system is also an integral part of the body's information transmission system. This system uses glands throughout the body that regulate many processes such as metabolism, digestion, blood pressure, and growth. Although the endocrine system is not directly related to the nervous system, they often work together.

central nervous system

The central nervous system (CNS) consists of the brain and spinal cord. The primary form of communication in the CNS is the neuron. The brain and spinal cord are vital for the functioning of the body, so there are a number of protective barriers around them: bones (skull and spine), and membrane tissues (meninges). In addition, both structures are located in the cerebrospinal fluid that protects them.

Why are the brain and spinal cord so important? It is worth thinking that these structures are the actual center of our "message system". The CNS is able to process all of your sensations and process the experience of those sensations. Information about pain, touch, cold, etc. is collected by receptors throughout the body and then transmitted to the nervous system. The CNS also sends signals to the body in order to control movements, actions, and reactions to the outside world.

Peripheral nervous system

The peripheral nervous system (PNS) consists of nerves that extend beyond the central nervous system. The nerves and nerve networks of the PNS are really just bundles of axons that emerge from nerve cells. Nerves range in size from relatively small to large enough to be easily seen even without a magnifying glass.

The PNS can be further divided into two different nervous systems: somatic and vegetative.

Somatic nervous system: conveys physical sensations and commands to movements and actions. This system consists of afferent (sensitive) neurons that deliver information from the nerves to the brain and spinal cord, and efferent (sometimes some of them are called motor) neurons that transmit information from the central nervous system to muscle tissues.

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. The autonomic nervous system can be further divided into the sympathetic and parasympathetic systems.

Sympathetic nervous system: The sympathetic nervous system controls the body's response to stress. When this system works, breathing and heart rate increase, digestion slows or stops, pupils dilate, and sweating increases. This system is responsible for preparing the body for a dangerous situation.

parasympathetic nervous system: The parasympathetic nervous system acts in opposition to sympathetic system. The e system helps to “calm down” the body after a critical situation. Heartbeat and breathing slow down, digestion resumes, pupils constrict and sweating stops.

Endocrine system

As noted earlier, the endocrine system is not part of the nervous system, but is still necessary for the transmission of information through the body. This system consists of glands that secrete chemical transmitters - hormones. They travel through the blood to specific areas of the body, including organs and tissues of the body. Among the most important endocrine glands are the pineal gland, hypothalamus, pituitary gland, thyroid gland, ovaries and testicles. Each of these glands perform specific functions in different areas of the body.

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 certain 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 organism with the conditions environment, 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 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 received 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 tropic hormone of the pituitary gland 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, then there will immediately be a violation of the ratios (quantitative and qualitative) in the entire system, carrying various endocrine diseases.

The regulation of the activity of all systems and organs of our body is carried out by nervous system, which is a collection of nerve cells (neurons) equipped with processes.

Nervous system a person consists of a central part (the brain and spinal cord) and a peripheral part (nerves leaving the brain and spinal cord). Neurons communicate with each other through synapses.

In complex multicellular organisms, all the main forms of activity of the nervous system are associated with the participation of certain groups of nerve cells - nerve centers. These centers respond with appropriate reactions to external stimulation from the receptors associated with them. The activity of the central nervous system is characterized by the orderliness and consistency of reflex reactions, that is, their coordination.

At the heart of all the complex regulatory functions of the body is the interaction of two main nervous processes - excitation and inhibition.

According to the teachings of I. II. Pavlova, nervous system has the following types of effects on organs:

–– launcher, causing or stopping the function of an organ (muscle contraction, gland secretion, etc.);

–– vasomotor, causing expansion or narrowing of blood vessels and thereby regulating the flow of blood to the organ (neurohumoral regulation),

–– trophic, which affects the metabolism (neuroendocrine regulation).

The regulation of the activity of internal organs is carried out by the nervous system through its special department - autonomic nervous system.

Together with central nervous system hormones are involved in providing emotional reactions and mental activity of a person.

Endocrine secretion contributes to the normal functioning of the immune and nervous systems, which in turn affect the work endocrine system(neuro-endocrine-immune regulation).

The close relationship between the functioning of the nervous and endocrine systems is explained by the presence of neurosecretory cells in the body. neurosecretion(from lat. secretio - separation) - the property of some nerve cells to produce and secrete special active products - neurohormones.

Spreading (like the hormones of the endocrine glands) throughout the body with blood flow, neurohormones capable of influencing the activity of various organs and systems. They regulate the functions of the endocrine glands, which, in turn, release hormones into the blood and regulate the activity of other organs.

neurosecretory cells, like ordinary nerve cells, they perceive signals coming to them from other parts of the nervous system, but then they transmit the information received already in a humoral way (not through axons, but through vessels) - through neurohormones.

Thus, combining the properties of nerve and endocrine cells, neurosecretory cells combine nervous and endocrine regulatory mechanisms into a single neuroendocrine system. This ensures, in particular, the ability of the body to adapt to changing environmental conditions. The combination of nervous and endocrine mechanisms of regulation is carried out at the level of the hypothalamus and pituitary gland.

Fat metabolism

Fats are digested the fastest in the body, proteins are the slowest. The regulation of carbohydrate metabolism is mainly carried out by hormones and the central nervous system. Since everything in the body is interconnected, any disturbances in the functioning of one system cause corresponding changes in other systems and organs.

About the state fat metabolism may indirectly indicate blood sugar indicating the activity of carbohydrate metabolism. Normally, this figure is 70-120 mg%.

Regulation of fat metabolism

Regulation of fat metabolism carried out by the central nervous system, in particular the hypothalamus. The synthesis of fats in the tissues of the body occurs not only from the products of fat metabolism, but also from the products of carbohydrate and protein metabolism. Unlike carbohydrates, fats can be stored in the body in a concentrated form for a long time, so the excess amount of sugar that enters the body and is not immediately consumed by it for energy, turns into fat and is deposited in fat depots: a person develops obesity. More details about this disease will be discussed in the next section of this book.

The main part of food fat exposed digestion V upper intestines with the participation of the enzyme lipase, which is secreted by the pancreas and the gastric mucosa.

Norm lipases blood serum - 0.2-1.5 units. (less than 150 U/l). The content of lipase in the circulating blood increases with pancreatitis and some other diseases. With obesity, there is a decrease in the activity of tissue and plasma lipases.

Plays a leading role in metabolism liver which is both an endocrine and exocrine organ. This is where oxidation takes place. fatty acids and cholesterol is produced, from which bile acids. Respectively, First of all, the level of cholesterol depends on the work of the liver.

bile, or cholic acids are end products of cholesterol metabolism. According to their chemical composition, these are steroids. They play an important role in the processes of digestion and absorption of fats, contribute to the growth and functioning of normal intestinal microflora.

Bile acids are part of the bile and excreted by the liver into the lumen of the small intestine. Together with bile acids, a small amount of free cholesterol is released into the small intestine, which is partially excreted in the feces, and the rest is dissolved and, together with bile acids and phospholipids, is absorbed in the small intestine.

The endocrine products of the liver are metabolites - glucose, which is necessary, in particular, for brain metabolism and the normal functioning of the nervous system, and triacylglycerides.

Processes fat metabolism in the liver and adipose tissue are inextricably linked. Free cholesterol in the body inhibits its own biosynthesis by the feedback principle. The rate of conversion of cholesterol into bile acids is proportional to its concentration in the blood, and also depends on the activity of the corresponding enzymes. The transport and storage of cholesterol is controlled by various mechanisms. The transport form of cholesterol is, as noted earlier, lipothyroidism.