What is the Endocrine System?

Endocrine system, an anatomical term, referred to as endocrine system. Refers to the systemic endocrine glands, which is another important functional regulatory system other than the nervous system. It can be divided into two categories: one is the visible organs that exist independently in the morphology and structure, that is, endocrine organs, such as pituitary, pineal gland, thyroid, parathyroid gland, thymus and adrenal gland; the other is scattered in other organs and tissues In the endocrine cell cluster, that is, endocrine tissue, such as pancreatic islets in the pancreas, interstitial cells in the testes, follicular cells and luteal cells in the ovary. Part of the endocrine organs and tissues participate in human sexual activities, which have a greater impact on human sexual activities. For example, the gonads-the sex hormones secreted by the ovaries and testes, are the material basis of human sexual activities.

Chinese name: Endocrine System
Foreign name: The endocrine system

Nature: biological
Nature: An integrated regulatory mechanism

Introduction to the endocrine system

The structural characteristics of the endocrine glands are: the glandular cells are arranged in a cord-like, lump-like, or vesicle-like manner, without ducts that discharge secretions, and the capillaries are abundant.

Hormones secreted by endocrine cells are divided into nitrogenous hormones (including amino acid derivatives, amines, peptides and protein hormones) and steroid hormones according to their chemical properties. The ultrastructural characteristics of cells that secrete ammonia-containing hormones are that the cytoplasm contains rough endoplasmic reticulum and Golgi complexes related to synthetic hormones, and membrane-encapsulated secretion particles. The ultrastructural characteristics of steroid hormone-secreting cells are that the cytoplasm contains a rich smooth surface endoplasmic reticulum related to the synthesis of steroid hormones, but does not form secretory particles; there are many mitochondria, and their ridges are mostly tubular; Many fat droplets, including cholesterol, are raw materials for synthetic hormones.

Each hormone acts on a certain organ or a certain type of cell in the organ, called the target organ or target cell of the hormone. The target cell has a receptor that binds to the corresponding hormone, and the receptor produces an effect after binding to the corresponding hormone. Nitrogen hormone receptors are located on the plasma membrane of target cells, while steroid hormone receptors are generally located in the cytoplasm of target cells.

Many organs are not endocrine glands. But tissues or cells that contain endocrine functions, such as brain (endorphin, gastrin, release factors, etc.), liver (angiotensinogen, 25-hydroxylated osteosteroids, etc.), kidney (renin, prostaglandin, 1 , 25 hydroxy osteosteroids, etc.). The same hormone can be synthesized in different tissues or organs, such as somatostatin (hypothalamus, islets, gastrointestinal, etc.), and peptide growth factors (nervous system, endothelial cells, platelets, etc.). The nervous system is closely related to the physiological aspects of the endocrine system. For example, the middle part of the hypothalamus is neuroendocrine tissue, which can synthesize antidiuretic hormones and oxytocins and store them along the axons in the posterior pituitary. Opioid peptides act on both the nervous system (belonging to a neurotransmitter) and the pituitary (being a hormone). The two affect and coordinate each other in maintaining the stability of the body environment. For example, in the mechanism of maintaining blood sugar stability, there are endocrine hormones such as insulin, glucagon, growth hormone, somatostatin, and adrenal corticosteroids. There is also involvement of the nervous system such as the sympathetic and parasympathetic nerves. Therefore, only when the nervous system and the endocrine system are normal can the internal environment of the body be maintained in an optimal state.

The main endocrine glands of the human body are: thyroid, parathyroid, adrenal, pituitary, pineal, islet, thymus and gonadal.

Endocrine hormone

Regulation of endocrine system hormones

In order to maintain the balance between the main hormones in the body, there is a complex system under the action of the central nervous system. Hormones are usually released at a relatively constant rate (such as thyroxine) or a certain rhythm (such as cortisol, sex hormones). Physiological or pathological factors can affect the basal secretion of hormones, and hormone levels are also monitored and regulated by sensors. The feedback regulation system is an important self-regulation mechanism in the endocrine system. Figure 6-1-1 shows that the information of the central nervous system passes through the hypothalamus, the pituitary reaches the peripheral glands, and the target cells exert physiological effects, any of which is positive or negative. Control of feedback regulation.

Endocrine system hormone transmission

Peptide hormones are mainly in free form in circulation. Sterol hormones and thyroid hormones (except aldosterone) both bind to specific plasma proteins with high affinity, and only a small amount (about 1-10%) is biologically active. Free state. This control of the ratio of binding to free can assist in regulating glandular function, which can regulate both biological activity and half-life.

Hormones and Receptors in the Endocrine System

Hormones need to bind to specific receptors to activate their physiological activities. Different hormones can have different processes; peptide hormones and catecholamines bind to cell surface receptors and exert their biological effects by affecting genes; insulin binds to cell surface receptors and enters cells to form pancreatin-receptor complex , And then combined with the second receptor to produce a biological effect, the binding of hormones and receptors is specific, and is reversible, in line with the law of quality and action.

Endocrine system thyroid

thyroid The gonads are located on both sides of the upper end of the trachea and are butterfly-shaped. It is divided into left and right leaves, and the isthmus is connected in the middle. The isthmus crosses the front of the second and third tracheal cartilage. Normal people move the thyroid up and down with the throat when swallowing. There are only a few muscles and fascia covering the front of the thyroid, so it can be felt on the surface when it is slightly enlarged.

The thyroid gland consists of many follicles of varying sizes. The follicular wall is a single layer of cubic epithelial cells, which are secretory cells of the glands. There is a gel in the bubble cavity, which is a storage substance secreted by the glandular cells. There are abundant capillaries and a small amount of connective tissue between the follicles.

The physiological function of the thyroid gland is mainly reflected in the following aspects.

Impact on metabolism

Thermal effect

Thyroid hormone can increase the oxygen consumption rate of most tissues and increase thermogenesis effects. The basal metabolic rate of patients with hyperthyroidism can increase by about 35%; while the basal metabolic rate of patients with hypothyroidism can decrease by about 15%.

Effect on metabolism of three major nutrients

Under normal circumstances, thyroid hormones mainly promote protein synthesis, especially the protein synthesis of bone, skeletal muscle, and liver. However, the excessive secretion of thyroid hormones, on the other hand, causes a large amount of protein, especially skeletal muscle, to be decomposed, thereby losing weight. In terms of glucose metabolism, thyroid hormone has the effect of promoting the absorption of sugar and the breakdown of liver glycogen. It also promotes the use of sugar in peripheral tissues. In short, it accelerates the metabolism of sugar and fat, especially the decomposition and oxidation of sugar, fat and protein in many tissues, thereby increasing the body's oxygen consumption and heat production.

Promote growth

It is mainly to promote the metabolic process, so that the normal growth and development of the human body, in particular, has a significant role in promoting the development of the bones and nervous system. Therefore, if the child has hypothyroidism during growth, he is hypoplastic, mentally retarded, and short.

Increase the excitability of the nervous system

Thyroxine can improve the excitability of the nervous system, especially the most obvious excitatory effect on the sympathetic nervous system. Thyroxine can directly affect the myocardium, which can increase myocardial contractility and speed up the heart rate. Therefore, patients with hyperthyroidism often show susceptibility to agitation, insomnia, tachycardia, and sweating.

Endocrine system parathyroid glands

Parathyroid glands There are four parathyroid glands, located in the posterior margin on both sides of the thyroid gland, two on the left and one on the left, and the total weight is about 100 mg. Parathyroid hormone secreted by the parathyroid gland regulates calcium and phosphorus metabolism in the body. It inhibits renal tubular reabsorption of phosphorus, promotes renal tubular reabsorption of calcium, and promotes bone cells to release phosphorus and calcium. Blood, so that the calcium content in the blood is increased, so the normal secretion of the parathyroid glands will not cause the calcium in the blood to be too low, and the blood phosphorus will not be too high, thus maintaining an appropriate ratio of calcium to phosphorus in the blood.

Endocrine system pituitary

brain

Pituitary The pituitary is an oval body that weighs less than 1 gram. It is located in the pituitary fossa of the skull base, and is connected to the lower thalamus by the pituitary stem. It is divided into the glandular part and the nerve part. It secretes a variety of hormones.

Growth hormone

Growth hormone is related to bone growth. If it is lacking in childhood, it will interrupt the growth of long bones and form dwarfism. If it is excessive, it will cause the growth of long bones in the whole body to become overgrowth and form giant disease.

Prolactin

Prolactin can promote breast proliferation and milk production and secretion.

Gonadotropin

Gonadotropins include follicle stimulating hormone and luteinizing hormone, which can promote the secretion of androgen and estrogen, and the maturation of follicles and sperm.

Corticotropin

Corticotropin mainly acts on the bundles and reticulum of the adrenal cortex and promotes the secretion of adrenal corticosteroids. A deficiency of this hormone will cause the same symptoms as Adesen's disease, but without skin pigmentation.

Thyroid stimulating hormone

Thyroid stimulating hormone acts on the thyroid gland, enlarges the thyroid gland, and increases the production and secretion of thyroid hormone. A deficiency of this hormone will cause symptoms of hypothyroidism.

Antidiuretic hormone

Antidiuretic hormone is a hormone produced by certain nerve cells in the hypothalamus and transported and stored in the pituitary. It acts on the kidneys, promotes reabsorption of water, and regulates water metabolism. In the absence of this hormone, polyuria occurs and is called diabetes insipidus. At high doses, it can shrink blood vessels and increase blood pressure, so it is also called vasopressin.

Oxytocin

Oxytocin is similar to antidiuretic hormone and is also produced by certain nerve cells in the hypothalamus. It stimulates uterine contractions and promotes milk excretion.

other

In addition to the hormones mentioned above, the pituitary also secretes thyroid-stimulating hormones, melanotrophs and so on.

Endocrine system islets

pancreatic

Islets An island is a cluster of cells scattered between acinars of the pancreas. Only 1% to 2% of the total volume of the pancreas. Islet cells are mainly divided into five types, of which A cells account for about 25% of the total islet cells and secrete glucagon; B cells account for about 60% of the total islet cells and secrete insulin. D-cells secrete less somatostatin. There are also PP cells and D_1 cells, both of which are few in number, and PP cells secrete pancreatic polypeptide.

The main role of insulin is to regulate the metabolism of sugar, fat and protein. It can promote the tissues of the whole body, especially accelerate the uptake of glucose by liver cells and muscle cells, and promote their storage and utilization of glucose. After liver cells and muscle cells absorb glucose in large quantities, it is converted into glycogen and stored on the one hand, or glucose is converted to fatty acids in liver cells and transported to adipose tissue for storage; on the other hand, it promotes the oxidation of glucose to high-energy phosphate compounds as energy source.

Another role of insulin is to promote the synthesis of fatty acids by liver cells. Glucose entering adipocytes is not only used to synthesize fatty acids, but also is mainly converted into -phosphoglycerol, which forms triglycerides with fatty acids and is stored in fat cells. In addition, insulin can inhibit lipolysis. When insulin is lacking, sugar cannot be stored and utilized, which not only causes diabetes, but also causes fat metabolism disorders, increased blood lipids, arteriosclerosis, and severe cardiovascular disease.

Insulin also plays an important role in protein metabolism. It promotes the entry of amino acids into cells and then directly acts on ribosomes to promote protein synthesis. It also inhibits protein breakdown. Very important for the body's growth process.

Blood glucose concentration is the most basic factor regulating insulin secretion. When the blood glucose concentration is increased, it can directly stimulate B cells, increase the secretion of insulin, and return the blood glucose concentration to normal levels; when the blood glucose concentration is lower than the normal level, the insulin secretion decreases, which can promote the increase of glucagon secretion and make the blood glucose level rise. In addition, amino acids and fatty acids can also promote insulin secretion.

Many gastrointestinal hormones and glucagons stimulate insulin secretion.

Glucagon has the opposite effect to insulin. It promotes glycogen breakdown and gluconeogenesis in the liver, which significantly increases blood sugar. It can also promote fat breakdown and increase ketone bodies.

Blood glucose concentration is an important factor regulating glucagon secretion. When the blood glucose concentration decreases, the secretion of glucagon increases; when it increases, the secretion decreases. Increased amino acids also promote glucagon secretion.

Insulin can promote the secretion of glucagon because of lowering the blood glucose concentration, but insulin can directly affect the adjacent A cells and inhibit the secretion of glucagon.

The vagus and sympathetic nerves that dominate the islets have opposite effects on glucagon secretion and insulin secretion. That is, vagal nerve excitement inhibits glucagon secretion; sympathetic excitement promotes its secretion.

Adrenal glands

kidney

Adrenal gland The upper glands are located above the kidneys, one on each side. The adrenal gland is divided into two parts: the peripheral part is the cortex, which accounts for the majority; the central part is the medulla, which accounts for the small part. The cortex is a target gland of the pituitary gland, while the medulla is directly dominated by presympathetic ganglion fibers.

The tissue structure of the adrenal cortex can be divided into three layers: globular zone, bundle zone and reticular zone. Globular glandular cells mainly secrete mineralocorticoids. The fascicular zone and the reticular zone secrete glucocorticoids, and the reticular zone also secretes a small amount of sex hormones.

On the one hand, adrenal glucocorticoids promote the breakdown of glucose and convert amino acids into glycogen in the liver; on the other hand, they have an anti-insulin effect, inhibit the use of glucose in peripheral tissues, and increase blood sugar. Glucocorticoids increase the decomposition of adipose tissue in the extremities and increase fat synthesis in the abdomen, face, shoulders and back. Therefore, hyperadrenal cortex function or taking too much glucocorticoids can appear physical features such as "concentric obesity" such as full moon face and buffalo back. Excessive glucocorticoids promote protein breakdown, making protein breakdown and renewal unbalanced, and more breakdown than synthesis, causing muscle weakness.

Glucocorticoids also have a certain effect on water and salt metabolism. It mainly affects the elimination of water. When it is lacking, it will have difficulty in draining water. At the same time, it can enhance the hematopoietic function of red blood cells and platelets by the bone marrow, increase the number of red blood cells and platelets, increase neutrophils, promote phagocytosis of eosinophils by the reticuloendothelial system, inhibit the proliferation of lymphoid tissues, and make the blood eosinophilic. Granulocytes and lymphocytes are reduced. In terms of response to blood vessels, it can not only slow down the degradation of epinephrine and norepinephrine; it can also increase the sensitivity of vascular smooth muscle to norepinephrine, and it can also reduce the permeability of capillaries. When the body encounters harmful stimuli such as trauma, infection, and poisoning, glucocorticoids can also enhance the body's stress ability. Due to the various functions and functions of adrenal glucocorticoids, it has been widely used in anti-inflammatory, anti-toxic, anti-shock and anti-allergic treatments.

The main role of adrenal mineralocorticoids is to regulate water and salt metabolism. Among these hormones, aldosterone has the strongest effect, followed by deoxycorticosterone. These hormones affect the kidneys on the one hand, promote the reabsorption of sodium and water by the renal tubules, and promote the excretion of potassium, on the other hand, affect the permeability of tissue cells, promote the transfer of sodium and water from the cells to the outside, and promote cells Potassium in the external fluid moves into the cell. Therefore, during periods of insufficient cortical function, blood sodium, plasma volume, and extracellular fluid are reduced. The amount of blood potassium, intracellular potassium, and intracellular fluid increased. Due to the decrease in plasma, blood pressure drops, which can cause circulatory failure in severe cases.

The sex hormones secreted by the adrenal cortex are mainly androgens, which can promote sexual maturity. Small amounts of androgens are important for women's sexual behavior. Excessive secretion of androgens can masculinize women.

The adrenal medulla is located in the center of the adrenal glands. Secretion of two hormones: epinephrine and norepinephrine, their biological role is closely related to the sympathetic nervous system, the effect is very wide. When the body encounters an emergency, such as fear, fright, anxiety, trauma, or blood loss, sympathetic nerve activity increases, and the medullary secretion of adrenaline and norepinephrine sharply increases. Makes the heartbeat stronger and faster, increases the cardiac output, increases blood pressure, and accelerates blood flow; bronchi relaxes to reduce and improve the supply of oxygen; liver glycogen is broken down, blood sugar is increased, and the supply of nutrients is increased.

Endocrine system thymus

Thymic hypoplasia The thymus is a lymphoid organ with endocrine functions. In the neonate and early childhood, the thymus is developed and has a large volume. After sexual maturity, it gradually shrinks and degenerates. The thymus is divided into left and right lobes, which are asymmetrical. The adult thymus is about 25 to 40 grams in color, grayish red, soft, and mainly located in the front of the upper mediastinum. The thymus is a hematopoietic organ during the embryonic period, and can produce lymphocytes, plasma cells, and myeloid cells during adulthood. Reticulum epithelial cells of the thymus can secrete thymosin, which can promote the production and maturation of T cells with immune function, and can inhibit the synthesis and release of acetylcholine in motor nerve endings. Therefore, when thymoma, myasthenia gravis occurs due to increased thymosin, which can lead to neuromuscular conduction disorders.

Endocrine system gonad

The gonads mainly refer to male testes and female ovaries.

Endocrine system testis

It can secrete the androgen testosterone (testosterone), whose main function is to promote the development of gonads and their accessory structures and the appearance of parasexual characteristics, as well as the role of promoting protein synthesis.

Endocrine system ovary

The ovaries secrete follicles, progesterone, relaxin, and female hormones.

Its functions are:

(1) Stimulate endometrial hyperplasia, promote thickening of the uterus, enlargement of the mammary glands, and appearance of female parasexual characteristics.

(2) Promote the proliferation of uterine epithelium and uterine glands, maintain the content of water, sodium and calcium in the body, and can lower blood sugar and increase body temperature.

(3) Promote the relaxation of cervical and pubic symphysis ligament, which is conducive to childbirth.

(4) Promoting feminization of female sexuality.

Endocrine system diffuse nerve

In addition to the above-mentioned endocrine glands, there are a large number of scattered endocrine cells in many other organs of the body. Many hormone-like substances secreted by these cells play a very important role in regulating the body's physiological activities. Pearse (1966) according to these endocrine cells can synthesize and secrete amines, and the cells produce amines by taking up amine precursors (amino acids) after decarboxylation, so these cells are collectively referred to as amine precursor decarboxylizing cells (amines) precursor uptake and decarboxylation cell (APUD cells).

With the continuous research of APUD cells, it was found that many APUD cells not only produce amines but also peptides, and some cells only produce peptides; and with the continuous expansion of APUD cell types and distribution, many neurons in the nervous system have been found It also synthesizes and secretes the same amines and / or peptides as APUD cells. Therefore, scholars have proposed that these neurons with secretory functions (called secretory neurons) and APUD cells are collectively called the diffuse neuroendocrine system (DNES). Therefore, DNES is a further development and expansion on the basis of APUD. It unifies the two major regulatory systems of the nervous system and endocrine system to form a whole, and jointly completes the regulation and control of the dynamic balance of the body's physiological activities.

The composition of DNES is known to have more than 50 types of cells, divided into two parts, the central and the surrounding. The central part includes cells of the hypothalamic-pituitary axis and pineal cells, such as the aforementioned arcuate nucleus, supraoptic nucleus, and paraventricular nucleus of the hypothalamic nodule and anterior regions, and the distal pituitary gland And middle endocrine cells. The peripheral part includes endocrine cells distributed in the stomach, intestine, pancreas, respiratory tract, urinary tract and reproductive tract, as well as parafollicular cells, parathyroid cells, adrenal medulla and other chromaffin cells of the thyroid gland, and small strong fluorescence of sympathetic ganglia Cells, carotid body cells, vascular endothelial cells, placental endocrine cells, and some cardiac muscle cells and smooth muscle cells. These cells produce amines such as catecholamines, dopamine, serotonin, norepinephrine, melatonin, histamine, etc .; there are more types of peptides, such as hypothalamus release inhibitory hormone, release inhibitory hormone, Vasopressin and oxytocin, the aforementioned various hormones of the pituitary gland, and gastrin, substance P, somatostatin, bombesin, pancreatin, cholecystokinin, neurotensin, Glucagon, insulin, enkephalin, vasoactive intestinal peptide, parathyroid hormone, calcitonin, renin, angiotensin, atrial natriuretic peptide, endothelin, etc. (Ou Kequn, Wu Liangfang, West China Medical University) The endocrine system is an in vivo information transmission system composed of endocrine glands and endocrine cells that decompose in certain tissues and organs. It is closely connected with the nervous system and cooperates with each other to regulate various functions of the body. Activities to maintain relatively stable internal environment. The main endocrine glands in the human body are pituitary, thyroid, parathyroid gland, adrenal glands, islets, gonads, pineal glands, and thymus; endocrine cells scattered in tissues and organs are more extensive, such as the digestive tract mucosa, heart, kidney, lung, and skin There are various endocrine cells in the place such as the placenta and placenta. In addition, there are nerve cells with endocrine function in the central nervous system, especially the inferior colliculus. High-efficiency biologically active substances secreted by endocrine glands or scattered endocrine cells, exert their regulating role through tissue fluid or blood transmission, and such chemicals are called hormones. With the development of endocrine research, the understanding of hormone delivery methods has gradually deepened. Most hormones are transported through the blood to target cells at long distances. This method is called telecring; some hormones can be transported to the neighboring cells without being transported through the blood. Paracrine; if the hormone secreted by the endocrine cells diffuses locally and returns to the endocrine cells to play a feedback role, this method is called autocrine. In addition, the hypothalamus has many nerve cells with endocrine functions. These cells can both produce and conduct nerve impulses, and they can synthesize and release hormones, so they are called neuroendocrine cells. The hormones they produce are called neurohormone. Neurohormones can be released along the axons of nerve cells and transported to the periphery by axons. This method is called neurocrine

Functions of the endocrine glands of the endocrine system :

Endocrine glands and tissue cells can secrete some biologically active substances (called hormones), which are directly released into the blood or lymph fluid, are transported throughout the body through the blood circulation, and act on certain organs that can be acted on (called target organs) Cells (called target cells), thereby regulating their physiological activities. Most of the endocrine glands are not directly related in morphology, but are closely related in function. Each endocrine gland is directly or indirectly functionally connected to other endocrine glands. The pituitary gland occupies an important position in the endocrine glands. A variety of hormones it secretes affect the functions of other endocrine glands, respectively; the latter can regulate the activity of the pituitary gland through feedback regulation. For example, thyroid-stimulating hormone secreted by the anterior pituitary gland can promote thyroid hormone secretion from the thyroid gland, but when the thyroxine in the blood increases, feedback inhibition of thyroid-stimulating hormone secretion from the anterior pituitary gland is fed back, thereby reducing thyroid secretion. This feedback regulation is an important factor in maintaining relatively stable hormone levels.

The endocrine system is closely related to the nervous system:

1. Structural basis:

(1) Structure of the hypothalamus:

There are two large cell nuclei in the hypothalamusthe supraoptic nucleus and the paraventricular nucleus. Some of the large cells that constitute them can both act as neurons to receive nerve impulses from the central nervous system of the brain or other parts, and convert them into secretion information of hormones and secrete active substances based on this information. Therefore, these cells are also called These are neurosecretory cells and these active substances are called neurohormones. These neurosecretory cells can be divided into two categories: large neurosecretory cells and small neurosecretory cells.

Among them, the axons secreted by the nerve-secreting large cells are projected to the pituitary gland, and vasopressin and oxytocin secreted by them are delivered there. The axons of the nerve-secreting small cells project into the median bulge, and the terminal end of the axon is in contact with the pituitary portal vein blood. As a result, they secrete a variety of pituitary hormones through the pituitary portal vein to reach the pituitary gland to regulate the secretion of various pituitary hormones. Pituitary hormones secreted by nerve-secreting small cells mainly include adrenocorticotropin-releasing hormone (CR) T, thyroid-stimulating hormone-releasing hormone (TRH), growth hormone-releasing hormone (GHRH), somatostatin (55), and gonadotropin-releasing Hormone (nGRH), prolactin release inhibiting hormone, etc. (D) A. Under the action of these hormones, the pituitary gland can secrete 7 hormones that act on peripheral glands and have many important functions and functions, including auxin (GH), prolactin (PRL), and thyroid-stimulating hormone (STH). , Adrenocorticotropic hormone (ACT) H, follicle stimulating hormone (FSH), luteinizing hormone (LH) and melatonin (MSH).

(2) Structure of pituitary:

The pituitary gland is composed of two parts: the neural pituitary (back pituitary) and the adenohypophysis (anterior pituitary). Among them, the pituitary gland is a neural tissue, which is actually a downward extension of the hypothalamus. All the hormones it contains are derived from large neuronal secretory cells in the hypothalamus. The pituitary gland is mainly composed of glandular cells and secretes a variety of gonadotropins that act on peripheral target glands. These hormonal functions are important and diverse, not only related to the body's growth and development, behavior, reproduction, nutrition absorption and metabolism, but also related to the coordination of multiple endocrine glands in the body.

2. Interaction between nervous system and endocrine system:

(1) Regulation and control of the nervous system on the endocrine system:

The hypothalamus secretes pituitary hormones to act on the pituitary gland, causing the pituitary hormones to act on the secretory cells of the target gland, causing it to secrete hormonesthis three-level system is called the hypothalamic-pituitary-target cell regulatory system; it It embodies the regulation of the endocrine system by the nervous system, and the hypothalamus is the recipient of nerve impulses, which is regulated by higher centers such as the hippocampus and the cerebral cortex. First, when efferent nerve impulses from the higher-level central nervous system reach the hypothalamus, neurons in the hypothalamus and paraventricular nucleus secrete pituitary hormones, which are first-class hormones; pituitary hormones reach the glands through the pituitary portal The pituitary gland stimulates or inhibits the pituitary gland to secrete a variety of hormonal hormones, that is, secondary hormones; hormonal hormones are transmitted to the whole body through blood circulation and act on peripheral target glands, so that endocrine cells of these target glands release peripheral hormones, which are tertiary hormones. In general, hormones secreted by higher endocrine cells can promote the activity of lower endocrine cells; hormones secreted by lower endocrine cells show a feedback regulation effect on the activities of high endocrine cells, most of which are inhibitory effects. This forms a closed regulatory loop, allowing the hormone levels in the blood to remain relatively stable.

(2) the impact of the endocrine system on the nervous system:

The endocrine system affects the functional activities of the nervous system through its secreted hormones, so that the nervous system functions more accurately and effectively. This is manifested in that many hormones are present in the brain and peripheral nerves, and they do not participate in the endocrine regulation of target tissues and target cells, but show obvious neural effects and exhibit broader physiological effects. Many hormones have corresponding receptors in the brain, and these receptors have a greater effect on nervous system function. For example, according to research, thyroid-stimulating hormone-releasing hormone (TRH) is widespread in the brain; adrenocorticotropic hormone-releasing hormone (CRT) has receptor distribution in the brain and at the margins.

3. The main areas where the nervous system and the endocrine system work together:

(1) Maintain the steady state of the internal environment:

Refers to a state of relatively constant physical and chemical properties of the internal environment, which is a complex dynamic balance maintained by various regulatory mechanisms in the body. The coordination and coordination of the nervous system and the endocrine system is an important factor in regulating and maintaining the homeostasis of the internal environment. Taking the regulation of drinking water in the body's water balance as an example, the water balance when the body is dehydrated can be achieved by two ways, that is, thirst urges people to drink more water, and the regulation of antidiuretic hormones. Among them, thirst is transmitted by the sensory nerves of the oral cavity and pharyngeal mucosa and some of the cell receptors of the hypothalamus, belonging to the role of the nervous system; and antidiuretic hormones act on the kidneys to promote water reabsorption, which is the credit of the endocrine system.

(2) Regulation of biological rhythm:

Nervous activity inside the body is constantly fluctuating due to endogenous or environmental factors; due to the dominance of the nervous system, hormones in the body also fluctuate in secretion speed and plasma concentration. This fluctuation affects almost all biological functions. The law that the joint fluctuations of these two major types of physiological activities are affected by time and the external environment is not only an important manifestation of biological rhythms (reflected as the biological clock, sleep and awakening, etc.), but also the internal reason for the existence of biological rhythms one. For example, experiments have shown that the growth hormone secretion activity of the pituitary gland varies with time. Human sleep stages include sleep states, slow-wave sleep, and another type of out-of-phase sleep with rapid eye movements. In the awake state, growth hormone secretion is less; after entering slow wave sleep, growth hormone secretion is significantly increased; after switching to heterosexual sleep, growth hormone secretion is reduced.

(3) Achieve stress response:

Stress response refers to the response of various hormones in the body to increase the body's resistance when the body is subjected to harmful stimuli. When the body suffers from noxious stimuli such as hypoxia, trauma, surgery, hunger, pain, cold or nervousness, anxiety and other noxious stimuli, the nervous system will promote the pituitary gland to increase the secretion of adrenal hormones. Increase the secretion of glucocorticoids. In addition, -endorphin, auxin, oxytocin, antidiuretic hormone, glucagon and aldosterone may also increase at this time. These hormones can enhance the body in an unfavorable state. Resistance.

(4) Neuroimmune regulation:

The joint effect of the nervous system and endocrine system is very prominent in the body's immunity. The nervous system can sense the stimulation of the body, and the immune system can sense the stimulation of tumors, viruses, and toxins. The two systems' regulating functions keep the body stable under physiological and pathological conditions. Hormones, as a common mediator of the two systems, turn the information they feel into the body's immune response.