Hormones are organic substances that affect metabolic processes, the functioning of tissues and organs, and the growth of the body. They are produced in humans by glands internal secretion, enter the blood or lymph and are delivered to target cells, which are affected.
Glands
They are called endocrine (internal secretion) because they do not have ducts to the outside, their secretion (hormones) remains inside the body. They regulate each other’s work and are able to accelerate or slow down the rate of hormone production, thereby affecting the functioning of all organs and tissues. We can say that the entire vital activity of the body rests on them. The endocrine glands include:
They perform various functions.
Pituitary gland and hypothalamus
This system is located in the occipital part of the brain, despite its small size(only 0.7 g), it is the “head” of the entire endocrine system. Most of the hormones produced by the pituitary gland regulate the functioning of other glands. The hypothalamus functions as a “sensor”, picking up signals from the brain about fluctuations in the level of other hormones, and sending a “command” to the pituitary gland that it is time to start working. Previously, it was also considered a full-fledged gland that influenced the functioning of the body, but thanks to research it was found that hormones are secreted by the pituitary gland, and the hypothalamus regulates these functions through releasing hormones. There are two types of them: some start the secretion process (releasing), others inhibit (stopping). Pituitary hormones include:
Thyroid and parathyroid glands
The thyroid gland is located in the upper third of the trachea, attaching to it connective tissue, has two lobes and an isthmus, resembling an inverted butterfly in shape. Its average weight is about 19 grams. The thyroid gland secretes thyroid hormones: thyroxine and triiodothyronine, which are involved in cellular metabolism and energy exchange. Maintaining human body temperature, maintaining the body during stress and physical activity, obtaining water by cells and nutrients, the formation of new cells - all this is the activity of thyroid hormones.
On the posterior wall of the thyroid gland there are small (no more than 6 g) parathyroid glands. Most often, a person has two pairs of them, but sometimes there are fewer, which is considered a variant of the norm. They produce hormones that regulate the level of calcium in the blood - paratin. They act in tandem with calcitonin, a thyroid hormone that lowers calcium levels, and they increase it. 
This is an unpaired small organ located between the hemispheres in the center of the brain. Its shape resembles a pine cone, for which it received its second name - pineal body. Weight is only 0.2 g. The activity of this gland depends on the illumination of the place where the person is. His leashes are attached to the optic nerves, through which he receives signals. In light it produces serotonin, in darkness it produces melatonin.
Serotonin also plays the role of a neurotransmitter - a substance that promotes the transmission of impulses between neurons, thanks to this property it improves a person’s mood, restrains the impulses of pain, and is responsible for muscle activity.
Once in the blood, it performs the functions of a hormone: it affects the development of inflammatory processes and blood clotting, slightly affects allergic reactions and regulates the functioning of the hypothalamus.
Melatonin is a hormone derived from serotonin, responsible for blood pressure, falling asleep and depth of sleep, activates the immune system, inhibits the synthesis of growth hormone, reducing the risk of tumor development, controls puberty and sexual arousal. During sleep, it restores damaged cells and inhibits the aging process. Because healthy good sleep so important for a person.
The pineal gland produces another hormone - adrenoglomerulotropin, its functions are not yet clear, scientists managed to find out that it affects the secretion of hormones by the adrenal medulla, but the whole process remains a mystery to them.
It is located behind the sternum and is a paired organ weighing about 20 grams. It grows until puberty, then begins to slowly atrophy; in older people it is almost indistinguishable from adipose tissue. The thymus gland is an important organ immune system, in which T cells mature, differentiate, and are immunologically “trained.” It produces hormones:
- Timalin;
- Thymosin;
- Thymopoietin;
- IGF-1;
Its role for the body has not yet been sufficiently studied. But its most important function is to prevent a person from dying from infections in childhood. It works intensively in babies, producing T-lymphocytes, endowing them with T-cell receptors and co-receptors (markers), forming acquired immunity. It is thanks to the thymus that a person does not get sick twice with diseases caused by the viruses of measles, chicken pox, rubella and many others.
They are located above each of the human kidneys, one weighs about 4 g, 90% of the gland is the adrenal cortex, the remaining 10% is the medulla. They produce different groups of hormones:
- Mineralocorticoids (water-salt balance);
- Glucocorticoids (glucose formation, anti-shock effect, immunoregulation, antiallergic effect);
- Androgens (protein synthesis and breakdown, glucose utilization, lowering cholesterol and lipid levels in the blood, reducing the amount of subcutaneous fat);
- Catecholamines (support the body during fear, rage, physical exertion, signaling the hypothalamus to strengthen the work of other glands);
- Peptides (cell regeneration, removal of toxins, increases tissue wear resistance).
It is located in the epigastric region, behind the stomach. Endocrine functions are performed only by a small part of it - the pancreatic islets. They are not located in one place, but are scattered unevenly throughout the gland. They secrete several hormones:
- Glucagon (increases blood glucose levels);
- Insulin (transportation of glucose into cells).
Most of the pancreas produces gastric juices, performing an exocrine function. 
Sex glands
The sex glands include the testes and ovaries; they, like the pancreas, are mixed glands, performing intrasecretory and exocrine functions.
The ovaries are paired female glands, located in the pelvic cavity, weighing about 7 grams. They produce steroid hormones: estrogens, gestagens, androgens. They ensure ovulation and the formation of the corpus luteum after conception. Their concentration is not constant, one of the hormones dominates, then another and a third, which creates a cycle.
The testicles are also a paired male organ; the glands are located in the scrotum. The main hormone of the testes is testosterone.
The gonads are responsible for the development of the genital organs and the maturation of the egg and sperm. They form secondary sexual characteristics: voice timbre, skeletal structure, location of fat deposits and hair, influence mental behavior - everything that distinguishes men from women.
The concept of endocrine glands and hormones. Endocrine glands, or endocrine, are called glands that do not have excretory ducts. Products of your life - hormones - they are released into the internal environment of the body, i.e. into the blood, lymph, tissue fluid.
Hormones- organic substances of various chemical natures: peptide And protein(protein hormones include insulin, somatotropin, prolactin, etc.), amino acid derivatives(adrenaline, norepinephrine, thyroxine, triiodothyronine), steroid(hormones of the gonads and adrenal cortex). Hormones have high biological activity (therefore they are produced in extremely small doses), specificity of action, and distant effects, i.e., they affect organs and tissues located far from the place of hormone production. Entering the blood, they are distributed throughout the body and carry out humoral regulation of functions organs and tissues, changing their activity, stimulating or inhibiting their work. The action of hormones is based on stimulation or inhibition of the catalytic function of certain enzymes, as well as influencing their biosynthesis by activating or inhibiting the corresponding genes.
The activity of the endocrine glands plays a major role in the regulation for a long time ongoing processes: metabolism, growth, mental, physical and sexual development, adaptation of the body to changing conditions of the external and internal environment, ensuring the constancy of the most important physiological indicators (homeostasis), as well as in the body’s reactions to stress.
When the activity of the endocrine glands is disrupted, diseases called endocrine diseases occur. Violations can be associated either with increased (compared to normal) activity of the gland - hyperfunction, in which an increased amount of hormone is formed and released into the blood, or with decreased activity of the gland - hypofunction, accompanied by the opposite result.
Intrasecretory activity of the most important endocrine glands. The most important endocrine glands include the thyroid, adrenal glands, pancreas, gonads, and pituitary gland (Fig. 13.4). The hypothalamus (subthalamic region of the diencephalon) also has an endocrine function. The pancreas and gonads are glands mixed secretion since, in addition to hormones, they produce secretions that flow through the excretory ducts, i.e., they also perform the functions of exocrine glands.
Thyroid gland(weight 16-23 g) is located on the sides of the trachea just below the thyroid cartilage of the larynx. Thyroid hormones (thyroxine And triiodothyronine) contain iodine, the intake of which with water and food is a necessary condition its normal functioning.
Thyroid hormones regulate metabolism, enhance oxidative processes in cells and the breakdown of glycogen in the liver, affect growth, development and differentiation of tissues, as well as activity nervous system. With hyperfunction of the gland, it develops Graves' disease. Its main signs: proliferation of gland tissue (goiter), bulging eyes, rapid heartbeat, increased excitability nervous system, increased metabolism, weight loss. Hypofunction of the gland in an adult leads to the development myxedema(mucous edema), manifested in a decrease in metabolism and body temperature, an increase in body weight, swelling and puffiness of the face, and mental disorders. Hypofunction of the gland in childhood causes growth retardation and the development of dwarfism, as well as a sharp lag in mental development (cretinism).
Adrenal glands(weight 12 g) - paired glands adjacent to the upper poles of the kidneys. Like the kidneys, the adrenal glands have two layers: the outer - cortical, and the inner - medulla, which are independent secretory organs that produce different hormones with different patterns of action.
Cells cortical layer hormones are synthesized that regulate mineral, carbohydrate, protein and fat metabolism. Thus, with their participation, the level of sodium and potassium in the blood is regulated, a certain concentration of glucose in the blood is maintained, and the formation and deposition of glycogen in the liver and muscles increases. The last two functions of the adrenal glands are performed jointly with pancreatic hormones. At hypofunction adrenal cortex develops bronze, or Addison's disease. Its signs: bronze skin tone, muscle weakness, increased fatigue, decreased immunity.
Brain layer adrenal glands produce hormones adrenalin And norepinephrine. They are released during strong emotions - anger, fear, pain, danger. The entry of these hormones into the blood causes rapid heartbeat, constriction of blood vessels (except for those of the heart and brain), increased blood pressure, increased breakdown of glycogen in liver and muscle cells to glucose, inhibition of intestinal motility, relaxation of the bronchial muscles, increased excitability of retinal and auditory receptors. and vestibular apparatus. As a result, a restructuring of body functions occurs under conditions of action extreme irritants and mobilization body strength to cope with stressful situations.
Pancreas has special islet cells, which produce the hormones insulin and glucagon, which regulate carbohydrate metabolism in the body. So, insulin increases the consumption of glucose by cells, promotes the conversion of glucose into glycogen, thus reducing the amount of sugar in the blood. Thanks to the action of insulin, the glucose content in the blood is maintained at a constant level, favorable for the course of vital processes. With insufficient insulin production, blood glucose levels increase, which leads to the development of the disease diabetes mellitus Sugar not used by the body is excreted in the urine. Patients drink a lot of water and lose weight. To treat this disease, insulin must be administered. Another pancreatic hormone - glucagon- is an insulin antagonist and has the opposite effect, i.e. it enhances the breakdown of glycogen to glucose, increasing its content in the blood.
The most important gland of the endocrine system of the human body is pituitary, or lower appendage of the brain (weight 0.5 g). It produces hormones that stimulate the functions of other endocrine glands. The pituitary gland has three lobes: anterior, middle and posterior, and each of them produces different hormones. So, in anterior lobe The pituitary gland produces hormones that stimulate the synthesis and secretion of thyroid hormones (thyrotropin), adrenal glands (corticotropin), gonads (gonadotropin), as well as growth hormone (somatotropin). If the secretion of somatotropin is insufficient, the child’s growth is inhibited and the disease develops pituitary dwarfism(the height of an adult does not exceed 130 cm). With an excess of the hormone, on the contrary, it develops gigantism. Increased secretion of somatotropin in an adult causes disease acromegaly, in which individual parts of the body grow - tongue, nose, hands. Hormones posterior lobe the pituitary gland enhances the reabsorption of water in the renal tubules, reducing urine output (antidiuretic hormone), increase contractions of the smooth muscles of the uterus (oxytocin).
Sex glands - testes, or testicles, in men and ovaries in women - belong to the glands of mixed secretion. The testes produce hormones androgens, and the ovaries -estrogens. They stimulate the development of reproductive organs, maturation of germ cells and the formation of secondary sexual characteristics, i.e., structural features of the skeleton, muscle development, distribution of hair and subcutaneous fat, structure of the larynx, voice timbre, etc. in men and women. The influence of sex hormones on morphogenesis processes is especially clearly manifested in animals when the gonads are removed (castracin) or are transplanted.
The exocrine function of the ovaries and testes is the formation and excretion of eggs and sperm through the genital ducts, respectively.
Hypothalamus. The functioning of the endocrine glands, which together form endocrine system carried out in close interaction with each other and in relationship with the nervous system. All information from the external and internal environment of the human body enters the corresponding zones of the cerebral cortex and other parts of the brain, where it is processed and analyzed. From them, information signals are transmitted to the hypothalamus - the subthalamic zone of the diencephalon, and in response to them it produces regulatory hormones entering the pituitary gland and through it exerting their regulatory effect on the activity of the endocrine glands. Thus, the hypothalamus performs coordinating and regulatory functions in the activities of the human endocrine system.
The table sorts all endocrine glands according to functionality and type of hormones secreted. Therefore, the components of the endocrine system should be considered separately in order to understand the importance and significance of each gland.
Features of endocrinology
The endocrine system is responsible for hormonal regulation of the entire body, which is carried out thanks to working together endocrine cells, individual tissues and special glands. The endocrine glands, or they are also called endocrine glands, direct their activity directly to the secretion of hormones, which enter directly into the interstitial and cerebral fluid, and also become part of the blood flow and the chemical composition of the lymph.
All endocrine glands form its system and are divided into functional parts:
- Glands in the endocrine zone (IZ)– help produce the required number of hormones.
- Glands of mixed secretion– they have more functional responsibilities and are divided according to the type of hormones secreted.
- Glandular cells– their role is to form a diffuse endocrine system. They are located in tissues and organs throughout the body.
Each endocrine gland is united with the central nervous system (CNS) by a morphological connection. Therefore, it belongs to either the central (for example, pituitary gland and hypothalamus) or peripheral (for example, thyroid and gonads) group.
Table describing all glands
The table shows the glands and their hormones:
| Glands | Hormones |
|---|---|
| Hypothalamus | Liberins and statins |
| Pituitary | Triple species. Hormone responsible for growth. Vasopressin. |
| In the thyroid area | Thyroid species containing iodine. Calcitonin. |
| Parathyroid | Parathyroid hormone |
| Pancreas | Insulin and Glucagon |
| Adrenal glands | Adrenalin Norepinephrine Glucocorticoids (cortisone) Aldosterone |
| Reproductive system area | Estrogens and Androgens |
Briefly about each endocrine gland from the table
The table provides a description of the glands:
| Name | Description |
|---|---|
| Pituitary | This is the most important endocrine gland of the entire endocrine system. The hormones it secretes regulate and activate the work of other glands. For example, triple hormones such as ACTH or LTG are aimed at regulating the functional activity of the thyroid and gonads, and also organize the work of the adrenal glands. |
| Hypothalamus | This endocrine gland is responsible for maintaining normal temperature conditions in the body; the hormones it secretes make it possible to monitor the level of temperature in the blood every second. The hypothalamus produces liberins and statins, which are involved in the regulation of the secretion of pituitary hormones. |
| Adrenal glands | Divided into several parts. The medulla is responsible for the production of adrenaline and norepinephrine. Thanks to these hormones, if necessary, the level of glucose in the blood increases, which is responsible for restoring the body’s energy costs. In addition, it stimulates the heart rate, speeds up breathing and increases blood pressure. Glucocorticoids or cortisones are produced in the cortex. These hormones regulate the process of protein breakdown. Their production is also very important when stressful situations arise. These types of hormones are responsible for the body’s resistance to stress and suppression of inflammatory processes. Another hormone produced by the adrenal glands is aldosterone. |
| Parathyroid | Each person has four endocrine parathyroid glands in the body, which are necessary for the production of parahormone. It regulates the level and concentration of calcium in the blood. |
| Thyroid gland | The main hormones produced by this endocrine gland are thyroxine (iodine-containing hormone) and calcitonin. Thyroxine is responsible for activating and maintaining the energy metabolism process. |
| Pancreas area | It produces the two most important hormones - insulin and glucagon. Insulin is necessary to reduce increased level glucose in the blood, and also assists the liver in processing glucose into glycogen for storage. This hormone also allows glucose to be quickly distributed throughout the cells of the body, bypassing the nerve cells. Glucagon allows you to increase the level of glucose in the blood when there is a lack of it, and also stimulates the breakdown of glycogen in the liver to form glucose. |
| Thymus (thymus gland) | Refers to the endocrine glands responsible for the functioning of the body's immune system. The peptide hormones it secretes are responsible for the production of T-lymphocytes, which are simply necessary for the normal functioning of the immune system. T-lymphocytes form the body's antiviral and anticancer defenses. Also, a sufficient level of this hormone in the blood allows you to reject foreign tissue after an organ transplant operation, thereby protecting the body from possible complications. |
| Sex glands | The ovaries produce female sex hormones estrogens, and the testes produce androgens. |
| Placenta | This gland produces two types of hormones: the main chorionic gonadotropin and the equally important lactogenic placental gonadotropin. Thanks to the first hormone, a woman learns about pregnancy. Its content in blood and urine is determined by laboratory tests. This hormone is responsible for the functioning of the corpus luteum of the ovaries so that the pregnancy proceeds safely until the end of the term. For the growth and development of the baby, the placenta produces two hormones: estrogen and progesterone. For the first two months, this function is performed by the corpus luteum, and then passes the baton to the placenta. |
What are hormones?
Gomones are substances that are produced by the endocrine glands of the endocrine system (see table). They enter the circulatory system and affect tissues. The target tissues are so called due to their high sensitivity and susceptibility to the production of certain hormones.
For example, the testes are the target organ for the absorption of testosterone, which is a type of hormone in men. And oxytocin affects the smooth muscles of the uterus and ensures the proper functioning of the mammary glands.
Characteristics of the effects of hormones on the body
Hormones of the endocrine glands are an integral part of the functioning of the entire body system and have various effects on it:
- Thanks to metabolic effect the hormone penetrates cells faster due to increased membrane permeability;
- Morphogenetic effect characterized by stimulation of skeletal growth and differentiation. In such cases, changes in the development of the organism due to heredity can be observed;
- Kinetic effect aimed at enhancing the functional activity of individual organs;
- Corrective effect associated with changes in the intensity of organ functioning even without the presence of hormones.
Physiological features
Endocrine glands– these are the organs of any living organism (human or animal), which are responsible for the production and release of specific substances (hormones, saliva, etc.) necessary for the proper physiological functioning of the body, as well as the active occurrence of biochemical processes in it.
The endocrine glands described in the table (endocrine and their components) produce hormones that enter directly into the blood and lymph. And the glands related to external secretion secrete necessary substances onto the surface of the body (sweat glands, etc.) or the mucous membrane (tear glands, etc.).
Let's try to list some physiological features of each endocrine gland:
- Hypothalamus, presented in the table, is the central link; it is responsible for human endocrine functions. This endocrine gland is located in the diencephalon at the intersection of the optic nerves, the infundibulum and the mamillary body. The table shows that the hypothalamus is responsible for the proper functioning of the cardiovascular system, regulation water balance in the body, contraction of the uterus after surgery or the end of the menstrual cycle, the formation of human physiological needs (hunger, satiety). The hypothalamus controls most hormonal processes, so if its functions are disrupted, many serious diseases can develop. The most common pathologies of the hypothalamus are prolactinoma and hypothalamic syndrome.
- Pituitary the leg is connected to the base of the brain (see table). Located in the sphenoid bone. It consists of three lobes: the anterior (adenohypophysis), intermediate and posterior (neurohypophysis). If the pituitary gland is deficient, the body may develop diabetes insipidus. But its excess leads to pathological disorders of the menstrual cycle in women and sexual impotence in men (impotence).
- Thymus or the thymus gland of internal secretion - a paired organ divided into lobes. It is located in the anterior mediastinum, in its upper section. The functioning of the immune system and the body’s resistance depend on the level of its content (described in the table). Most often, the endocrine gland develops before the onset of puberty; later it does not perform essential functions.
- Thyroid gland internal secretion (as seen in the table) is divided into two lobes and is located behind the thyroid cartilages on both sides of the trachea. Pathology in the development of the thyroid gland is characterized by increased secretion of hyperthyroidism, which leads to weight loss, tachycardia and disruption of basic metabolism in the body. Myxedema is a pathological condition of hypofunction of the thyroid gland, as a result of which the activity of the central nervous system decreases. Most often this occurs from a lack of iodine in the body. Popularly, this disease is called “goiter” - an overly enlarged thyroid gland.
- Parathyroid internal secretion secretes parahormone, which is responsible for the balance of calcium in the body. Thanks to it, calcium is freely removed from the bone cavities and enters the blood.
- Adrenal glands. Where do the hormones secreted by the endocrine glands of the adrenal glands go? The hormones of this gland enter not only the blood, but also the cells of the entire body. They are responsible for the metabolism of minerals and also control the conversion of proteins, fats and carbohydrates into useful substances. Adrenaline produced in the adrenal glands has a positive effect on a person’s emotional background, and norepinephrine controls the nervous system.
- Pancreas The internal secretion is separated from the stomach by the omental bursa. Certain cells of this gland, as indicated in the table, are involved in the production of digestive juice, others produce insulin, the deficiency of which can lead to the development of diabetes.
- Activity of the gonads of internal secretion, described in the table, is aimed at the maturation of sperm and eggs, as well as the production of sex hormones. The sex glands in girls (ovaries) are located in the pelvic area and control endocrine and generative processes. The secretion glands in males are located in the scrotum and perform the same functions. They are where sperm mature and are part of the testosterone production process (as described in the table).
Conclusion
Problems in the functioning of the endocrine system, disruption of the functions of its endocrine glands (see table) can lead to serious pathologies in the functioning of the whole organism. And the absence of any endocrine gland often leads to death, since its replacement or compensation is impossible.
Today, potent drugs can only replace thyroid hormones.
Endocrine glands
General data Endocrine glands, or endocrine organs (from the Greek endo-inward, krino- secrete), are glands whose main function is the formation and release of special active chemical substances into the blood - hormones. Hormones (from the Greek hormao - I excite) have a regulatory effect on the function of the whole organism or individual organs, mainly on different aspects of metabolism. The study of endocrine glands - endocrinology. The endocrine glands include: hypophysis, epiphysis, thyroid glands, parathyroid glands, thymus gland, pancreatic islets, adrenal glands, endocrine part of the gonads (ovaries in women, testes in men). Endocrine function is also inherent in some other organs (different parts of the digestive canal, kidneys, etc.), but in these organs it is not the main one. The endocrine glands differ in their structure and development, as well as in chemical composition and the action of the hormones they secrete, but they all have common anatomical and physiological features. First of all, all endocrine organs are glands that do not have excretory ducts. The main tissue of almost all endocrine glands, which determines their function, is the glandular epithelium. There is a rich blood supply to the glands. Compared to other organs of the same weight (mass), they receive significantly more blood, which is associated with the intensity of metabolism in the glands. Inside each gland there is an abundant network of blood vessels, and the glandular cells are adjacent to blood capillaries, the diameter of which can reach 20-30 microns or more (such capillaries are called sinusoids). The endocrine glands are supplied with a large number of nerve fibers, mainly from the autonomic (autonomic) nervous system. The endocrine glands do not function in isolation, but are connected in their activities into a single system of endocrine organs. The regulation of body functions through the blood by active chemicals is called humoral regulation. Hormones play a leading role in this regulation. Humoral regulation is closely related to the nervous regulation of the activity of various organ systems, therefore, in the conditions of a whole organism, we are talking about a single neurohumoral regulation. Dysfunction of the endocrine glands is the cause of diseases called endocrine diseases. In some cases, these diseases are based on excess production of hormones (hyperfunction of the gland), in others, insufficient production of hormones (hypofunction of the gland). PITUITARY Gland (hypophys) The pituitary gland or lower appendage of the brain is a small oval-shaped gland weighing (mass) 0.7 g. It is located at the base of the skull in the fossa of the sella turcica of the sphenoid bone, covered on top by the process of the dura mater (diaphragm of the sella turcica). With the help of the so-called pituitary stalk, the pituitary gland is connected to the funnel, which extends from the gray tuberosity of the subtubercular region (hypothalamus). The pituitary gland has two lobes - anterior and posterior. The anterior lobe developed by protrusion from the primary oral cavity of the embryo, consists of glandular epithelial cells and is called the adenohypophysis. The anterior lobe has several parts. The part adjacent to the posterior lobe of the pituitary gland is called the pars intermedius.
The glandular cells of the anterior pituitary gland differ in their structure and the hormone they secrete: somatotropocytes secrete somatropic hormone, lactocytes secrete lacotropic hormone (proclatin),
Corticotropocytes - adrenocorticotropic hormone (ACTH), thyrotropocytes - thyroidprop hormone, follicle-stimulating and luteinizing gonadotropocytes - gonadotropic hormones. Somatotropic hormone has an effect on the entire body - it affects its growth (growth hormone). Lactotropic hormone (prolactin) stimulates milk secretion in the mammary glands and affects the function of the corpus luteum in the ovaries. Adrenocorticotropic hormone (ACTH) regulates the function of the adrenal cortex, activating the formation of glucocorticoids and sex hormones in it. Thyroid-stimulating hormone stimulates the production of hormones by the thyroid gland. Gonadotropic hormones of the anterior pituitary gland have an effect on the sex glands (gonads): they affect the development of follicles, ovulation, the development of the corpus luteum in the ovaries, spermatogenesis, the development and hormone-forming function of interstitial cells in the testes (testes). The intermediate part of the anterior pituitary gland contains epithelial cells that produce intermedin (melanocyte-stimulating hormone). This hormone affects pigment metabolism in the body, in particular the deposition of pigment in the skin epithelium. The posterior lobe of the pituitary gland developed by protruding from the diencephalon from the process of the infundibulum) consists of neuroglial cells: and is also called the neurohypophysis. It secretes antidiuretic hormone and the hormone oxytocin. These hormones are produced by the neurosecretory cells of the hypothalamus and, along the nerve fibers coming from them as part of the infundibulum, enter the posterior lobe of the pituitary gland, where they accumulate (deposit). From the posterior lobe they enter the blood as needed. 
EPIPHYSUS OF THE BRAIN (epiphysis cerebri)
The pineal gland of the brain, or pineal body, is a small gland weighing (mass) up to 0.25 g and shaped like a fir cone. It is located in the cranial cavity above the plate of the roof of the midbrain, in the groove between its two upper colliculi, and is connected with the visual hillocks of the diencephalon with the help of cherry leashes (the gland developed from this brain). The pineal gland of the brain is covered with a connective tissue membrane, from which trabeculae (septa) penetrate inside, dividing the substance of the gland into small lobules, the so-called pinelocytes and neuroglial cells. It is believed that pinealocytes have a secretory function and produce various substances, including melatonin. A functional connection of the pineal gland with other endocrine glands, in particular with the gonads, has been established (in girls, the pineal gland inhibits the development of the ovaries until a certain age). 
THYROID GLAND (glandula thyreoidea)
The thyroid gland is the largest endocrine gland. Its weight (mass) is 30-50 g. The gland is divided into right and left lobes and an isthmus connecting them. The gland is located in the anterior part of the neck and is covered with fascia. The right and left lobes of the gland are adjacent to the thyroid cartilage of the larynx and to the cartilage of the trachea: the isthmus is located in front of the second - fourth tracheal rings. On the outside, the gland has a fibrous (fibrous) capsule, from which septa extend inward, dividing the substance of the gland into lobules. In the lobules between the layers of connective tissue, accompanied by vessels and nerves, there are follicles (vesicles). The wall of the follicles consists of one layer of glandular cells - thyrocytes. The size (height) of thyrocytes changes in connection with their functional state. With moderate activity they have a cubic shape, and with increased secretory activity they swell and take the form of prismatic cells. The cavity of the follicles is filled with a thick iodine-containing substance - colloid, which is secreted by thyrocytes and consists mainly of thyroglobulin. Thyroid hormones - thyroxine and triiodothyronine - affect various types metabolism, in particular, enhance protein synthesis in the body. They also influence the development and activity of the nervous system. Diseases caused by dysfunction of the thyroid gland include thyrotoxicosis, or Baset's disease (observed with hyperfunction of the gland), and hypothyroidism - myxedema in adults and congenital myxedema or cretinism in childhood. The thyroid gland, parathyroid glands and thymus gland develop from the rudiments of the gill pouches (of endodermal origin) and together constitute the bronchial group of glands. 
PARATHYROID GLANDS (glandulae parathyreoideae) The parathyroid glands - two upper and two lower - are small oval or round bodies weighing (mass) each up to 0.09 g. They are located on the posterior surface of the right and left lobes of the thyroid gland along its arterial vessels . The connective tissue capsule of each gland sends processes inside. Between the layers of connective tissue there are glandular cells - parathyroid cells. The hormone of the parathyroid glands - parathyroid hormone - regulates the exchange of calcium and phosphorus in the body. Insufficiency of parathyroid hormone leads to hypocalcemia (decreased calcium levels in the blood) and increased phosphorus levels, while the excitability of the nervous system changes and convulsions are observed. With excessive secretion of parathyroid hormone, hypercalcemia and a decrease in phosphorus levels occur, which may be accompanied by softening of the bones, degeneration of the bone marrow and other pathological changes. 
thymus gland (thymus)
The thymus gland consists of two lobes - right and left, connected by loose connective tissue. Located in the upper part of the anterior mediastinum behind the manubrium of the sternum. In children, the upper end of the gland can protrude through the upper thoracic opening into the neck area. The weight (mass) and size of the gland change with age. In a newborn it weighs about 12 g, grows rapidly in the first 2 years of the child’s life, reaching its greatest weight (weight up to 40 g) at the age of 11-15 years. From the age of 25, age-related involution of the gland begins - a gradual decrease in glandular tissue in it with its replacement by fatty tissue. The thymus gland is covered with a connective tissue capsule, from which processes extend, dividing the substance of the gland into lobules. Each lobule contains a cortex and a medulla.
The basis of the lobules is made up of epithelial cells arranged in the form of networks, between which there are lymphocytes. The cortex, compared to the medulla of the gland lobules, contains significantly more lymphocytes and is darker in color. Inside the medulla there are concentric bodies, or Hassall's bodies, consisting of epithelial cells arranged in circular layers. The thymus gland plays an important role in the body's protective (immune) reactions. It produces a hormone, thymosin, which affects the development of lymph nodes and stimulates the reproduction and maturation of lymphocytes and the production of antibodies in the body. The thymus gland produces T lymphocytes, one of two types of lymphocytes circulating in the blood. The hormone thymosin regulates carbohydrate metabolism and calcium metabolism in the blood. 
PANCREASIC ISLANDS
(insulae pancreaticae)
Pancreatic islets are round formations of varying sizes. Sometimes they consist of several cells. Their diameter can reach 0.3 mm, rarely 1 mm. Pancreatic islets are located in the parenchyma of the entire pancreas, but mainly in its tail part. There are two main types of glandular cells in islets: B cells and A cells. The majority of islet cells are B cells, or basophil cells. They have a cubic or prismatic shape and produce the hormone insulin. A cells, or acidophilus cells, are found in smaller numbers, have a round shape and secrete the hormone glucagon.
Both hormones affect carbohydrate metabolism: insulin, increasing the permeability of cell membranes for glucose, accelerates the transition of glucose from the blood to muscle and nerve cells: glucagon increases the breakdown of liver glycogen into glucose, which leads to an increase in its content in the blood. Insufficient insulin production is the cause of diabetes. 
ADRENAL GLAND
(glandula suprarenalis)
The adrenal gland or adrenal gland, right and left, is located in the retroperitoneum above the upper end of the corresponding kidney. The right adrenal gland is triangular in shape, the left is lunate: the weight (mass) of each gland is 20 g.
The adrenal gland has two layers: the outer yellow layer is the cortex and the inner brown layer is the medulla. These two substances differ in their structure and origin, as well as in the hormones they secrete, and merged into one gland during development.
The cortex (bark) is a derivative of the mesoderm, develops from the same rudiment as the gonads, consists of epithelial cells, between which there are thin layers of loose connective tissue with blood vessels and nerve fibers. Depending on the structure and location of the epithelial cells, three zones are distinguished: the outer - glomerular, the middle - fasciculate and the inner - reticular. In the zona glomerulosa, small epithelial cells form cords in the form of tangles. The zona fasciculata contains larger cells lying in parallel cords (bundles). In the reticular zone there are small glandular cells arranged in the form of a network.
Hormones of the adrenal cortex are produced in its three zones and, according to the nature of their action, are divided into three groups - mineralocorticoids, glucocorticoids and sex hormones.
Mineralocorticoids (aldosterone) are secreted in the zona glomerulosa and affect water-salt metabolism, in particular sodium metabolism, and also enhance inflammatory processes in the body. Glucocorticoids (hydrocortisone, corticosterone, etc.) are produced in the zona fasciculata, take part in the regulation of carbohydrate, protein and fat metabolism, increase the body's resistance and weaken inflammatory processes. Sex hormones (androgens, estrogens, progesterene) are produced in the reticularis zone and have an effect similar to the hormones of the gonads.
Dysfunction of the adrenal cortex leads to pathological changes in various types of metabolism and changes in the sexual sphere. With insufficient function (hypofunction), the body's resistance to various harmful influences (infection, injury, cold) is weakened. A sharp decrease in the secretory function of the adrenal glands occurs with bronze disease (Addison's disease).
Removal of the cortical part of both adrenal glands in animal experiments leads to death.
Hyperfunction of the adrenal glands causes abnormalities in various organ systems. Thus, with hypernephroma (tumor of the cortex), the production of sex hormones sharply increases, which causes earlier puberty in children, the appearance of a beard, mustache and male voice in women, etc. The medulla of the adrenal glands is a derivative of the ectoderm, develops from the same rudiment as the nodes of the sympathetic trunk, consists of glandular cells called chromaffin (colored brown with chromium salts). The medulla hormones adrenaline and norepinephrine have an effect on various body functions, similar to the influence of the sympathetic department of the autonomic (autonomic) nervous system. In particular. adrenaline stimulates the heart. constricts skin blood vessels. relaxes the muscular lining of the intestine (reduces peristalsis), but causes contraction of the sphinkers, dilates the bronchi, etc. 
GENITAL GLANDS (ENDOCRINE PART)
The ovaries produce two types of female sex hormones - estradiol and progesterone. Estradiol is produced by cells of the granular layer of developed follicles (the former name of the hormone follculin). Progesterone is secreted by the corpus luteum of the ovary, which forms at the site of the ruptured follicle. As noted, the corpus luteum functions as an endocrine organ for a long time in a pregnant woman.
In the area of the ovarian hilum there are special cells that produce small amounts of male sex hormones.
The male sex hormones, testosterone, are produced in the testes or testes. The so-called interstitial (intermediate) cells located between the loops of convoluted seminiferous tubules in the testicular lobules participate in the formation of these hormones. The cells of the convoluted tubules themselves may also participate in the production of testosterone.
The testicles normally produce small quantities of female sex hormones - estrogens.
Sex hormones are necessary for puberty and normal sexual activity. Puberty refers to the development of the genital organs (primary sexual characteristics) and secondary sexual characteristics. Secondary sexual characteristics include all features, with the exception of the genital organs, in which the female and male bodies differ from each other. Such signs are differences in the skeleton (different thickness of bones, width of the pelvis and shoulders, shape of the chest, etc.), the type of distribution of hair on the gel (the appearance of a beard, mustache, hair on the chest and abdomen in men). the degree of development of the larynx and the associated difference in voice timbre, etc.) The process of puberty occurs in boys aged 10-14 years, in girls aged 9-12 years, and continues in boys aged 14-18 years and in girls at the age of 13-16 years. As a result of this process, the genitals and the entire body achieve such development that the ability to bear children becomes possible. Sex hormones also influence the metabolism in the body (increase basal metabolism) and the activity of the nervous system.
Disruption of the endocrine function of the gonads can cause changes both in the genital area and in the entire body. Age-related changes in the hormonal function of the gonads are observed during menopause. As the body ages, the production of hormones in the gonads decreases. 
The regulation of the physiological functions of the body is carried out using two systems - nervous and humoral. In the body they act in concert. Nervous regulation occurs quickly, in a split second, while humoral regulation occurs slowly. This type of regulation is limited by the speed of blood movement through the vessels (0.005-0.5 m/s). Nervous and humoral regulation are closely related to each other and carry out a single neurohumoral regulation. The central nervous system, including its highest section - the cerebral cortex, regulates the functions of the endocrine glands. This is done by transmitting nerve impulses directly to organs and tissues. Humoral regulation involves the regulating influence of biologically active substances carried by blood, lymph, and tissue fluid.
Glands that do not have excretory ducts and secrete their secretions (hormones) directly into the tissue fluid and blood are called endocrine(Fig. 193).
The process of production and release of active substances by endocrine glands is called internal secretion, and the substances are called hormones.
Hormones- chemical compounds with high biological activity, in small doses, give a significant physiological effect. Based on their chemical composition, they are distinguished: 1) steroid hormones; 2) proteins and peptides; 3) derivatives of amino acids.
Hormones are characterized by:
1) distant action. The organs and systems on which hormones act are located far from the place of their formation in the endocrine glands;
2) strict specificity of action. The reaction of organs and tissues to hormones is strictly specific. The specificity of the action of hormones is ensured by the presence of receptor molecules in cells. Only organ cells have receptors for the corresponding hormone.
Rice. 193.Location of endocrine glands (diagram)1 - pineal body;2 - pituitary gland; 3 - thyroid and parathyroid glands;4 - thymus gland (thymus);5 - adrenal gland; 6 - islet part of the pancreas;7 - intrasecretory part of the testicles (in men);8 - intrasecretory part of the ovary (in women).
on-targets, capable of reading chemically encoded information due to this;
3) high biological activity. Hormones are produced by endocrine glands in very small quantities.
Hormones are involved in the regulation and integration of all body functions. They contribute to the body’s adaptation to changing conditions of the external and internal environment and restore the altered balance of the internal environment.
The endocrine glands have different locations, but they are closely related to each other. Violation of the function of one leads to changes in the activity of others. A certain level of hormones is required for the body to function. A lack of one or another hormone indicates a decrease in activity (hypofunction) of this gland, excess - about increased activity (hyperfunction).
With hypo- and hyperfunction of the glands, various endocrine diseases occur.
The endocrine glands are abundantly supplied with blood and lymphatic vessels. The fibers of the autonomic nervous system are suitable for them.
Endocrine glands are divided into dependent and independent from the anterior lobe pituitary gland
To the glands dependent on the pituitary gland include thyroid gland cortical substance of the adrenal glands gonads. The relationship between the anterior lobe of the pituitary gland and these glands is based on the type of direct and feedback connections.
Tropic hormonesthe anterior lobe of the pituitary gland activates the activity of the glands. Gland hormones, acting on the anterior lobe of the pituitary gland, inhibit the formation and release of the corresponding hormone.
TO independent of the anterior lobe pituitary gland include parathyroid glands, pineal gland, pancreatic islets(islets of Langerhans of the pancreas), adrenal medulla, paraganglia.
The highest center for the regulation of endocrine functions is hypothalamus(division of the diencephalon). It unites non-
regulating and endocrine mechanisms of regulation into the general neuroendocrine system. The hypothalamus forms a single functional complex with the pituitary gland. The hypothalamus contains neurons of the usual type and neurosecretory cells. Both types of cells produce protein secretions and mediators. In neurosecretory cells, protein synthesis predominates, and neurosecret is released into the blood. Thus, the nerve impulse is converted into a neurohumoral one.
Pituitary
Pituitary(brain appendage) - a small gland weighing 0.5-0.7 g. Located in the pituitary fossa of the sella turcica of the sphenoid bone. Through an opening in the diaphragm of the sella, the pituitary gland is connected to the infundibulum of the hypothalamus of the diencephalon. The pituitary gland consists of three lobes: front(adenohypophysis), intermediate And rear(neurohypophysis).
IN anterior lobe The pituitary gland produces a number of hormones: somatotropic, thyrotropic, gonadotropic, adrenocorticotropic and others.
Somatotropicthe hormone controls the growth of bones, muscles, organs, regulates metabolic processes in the body.
At hyperfunction occurs in childhood gigantism(Fig. 194), in an adult - acromegaly(increase individual parts body: arms, legs, nose, etc.) (Fig. 195). At hypofunction in childhood a person remains a dwarf. Pituitary dwarfs have normal mental development and correct body proportions (Fig. 194). Hypofunction in adults causes changes in metabolism, which leads to either general obesity or severe weight loss.
Thyroid-stimulating hormone controls the function thyroid gland affects its development and hormone production.
Adrenocorticotropic hormone regulates functions cortical substances adrenal glands
Rice. 194.Gigantism. The boys are the same age (14 years old). Left - pituitary dwarf- height 100 cm; on the right - pituitary giant - height 187 cm; in the center - a normal boy - height 148 cm.
Rice. 195.Patient with acromegaly. Overgrowth of the lower jaw, nose, hands and feet.
TO gonadotropic hormones include follicle-stimulating(promotes the growth of germ cells), luteinizing(increases the formation of sex hormones and the growth of the corpus luteum), luteotropic (promotes the formation of the corpus luteum and the synthesis of progesterone), prolactin(increases milk production by the mammary glands).
Intermediate part the anterior pituitary gland secretes hormones melanocytotropin, regulating the synthesis of melanin pigment, and lipotropin, activating fat metabolism.
Posterior pituitary gland (neurohypophysis) is formed by nervous tissue and does not synthesize hormones. Biologically active substances are transported to the posterior lobe of the pituitary gland oxytocin And vasopressin. They are produced by the nuclei of the hypothalamus, accumulate in the pituitary gland and are released into the blood. Vasopressin has a vasoconstrictor and antidiuretic effect.
Oxytocinacts on the smooth muscles of the uterus, enhancing its contractions at the end of pregnancy, and stimulates milk secretion.
Thyroid gland
Thyroid gland located on the neck in front of the larynx. It has two lobes and an isthmus. The weight of the gland in an adult is 20-30 g. The gland is covered on the outside with a connecting capsule, which divides the organ into lobules.
Slicesconsist of vesicles (follicles), which are structural and functional units. The thyroid gland produces iodine-rich hormones thyroxine And triiodothyronine. Their main function is to stimulate oxidative processes in the cell. Hormones affect water, protein, carbohydrate, fat, mineral metabolism, growth, development and tissue differentiation. They affect the functions of the central nervous system and higher nervous activity.
Hormone thyrocalcitonin participates in the exchange of calcium and phosphorus, reducing the calcium content in the blood and the reabsorption of calcium from the bones.
Rice. 196.Graves' disease, characterized by exophthalmos. The patient before surgery (left) and after surgery (right).
At hyperfunction thyroid gland occurs Graves' disease(enlarged thyroid gland, increased excitability of the nervous system, basal metabolism, bulging eyes (exophthalmos), decreased body weight) (Fig. 196).
At hypofunction of the gland occurs in childhood cretinism(stunted growth, mental and sexual development). With hypofunction, an adult develops myxedema(decreased basal metabolism, obesity, apathy, decreased body temperature, mucous tissue swelling).
At iodine deficiency people suffer in water endemic goiter(secreting tissue grows in the thyroid gland).
Parathyroid glands
Parathyroid glands (upper and lower) are located on the posterior surface of the thyroid lobes. Their number can vary from 2 to 8. The total mass of the parathyroid gland in an adult is from 0.2-0.35 g. Epithelial cells these glands produce parathyroid hormone, involved in the metabolism of calcium and phosphorus in the body.
It promotes the release of calcium and phosphorus ions from bones into the blood. Parathyroid hormone increases the reabsorption of calcium by the kidneys, reducing calcium excretion in the urine and increasing its content in the blood.
Adrenal glands
Adrenal glands- paired organs located retroperitoneally directly above the upper poles of the kidneys. The weight of one adrenal gland in an adult is about 12-13 g. They consist of two layers: outdoor(cortical) and internal(cerebral).
IN cortex three groups of hormones are produced: glucocorticoids, mineralocorticoids And sex hormones.
Glucocorticoids (hydrocortisone, corticosterone and etc.) affect the metabolism of carbohydrates, proteins, fats, stimulate the synthesis of glycogen from glucose, and have an anti-inflammatory effect. Glucocorticoids ensure the body's adaptation to emergency conditions.
Mineralocorticoids (aldosterone, etc.) regulate the exchange of sodium and potassium, acting on the kidneys. Aldosterone enhances the reabsorption of sodium in the renal tubules, enhances the release of potassium, participates in the regulation of water-salt metabolism, blood vessel tone, and helps increase blood pressure.
Sex hormones (androgens, estrogens, progesterone) ensure the development of secondary sexual characteristics.
At hyperfunction adrenal glands increase the synthesis of hormones, especially sex hormones. At the same time, secondary sexual characteristics change (women develop a beard, mustache, etc.).
At hypofunction develops bronze disease. The skin takes on a bronze color, loss of appetite, increased fatigue, nausea, and vomiting are observed.
Medullaadrenal glands secretes adrenalin And norepinephrine, participating in carbohydrate metabolism and affecting the cardiovascular system.
Adrenalinincreases systolic blood pressure and cardiac output, increases heart rate, and dilates coronary vessels.
Norepinephrinereduces heart rate and cardiac output.
Endocrine part of the pancreas
The endocrine part of the pancreas is represented by islets of Langerhans. The largest number of them is located in the tail of the pancreas. β cells islets produce the hormone insulin, and α cells- glucagon. These hormones have the opposite effect. Insulin promotes the transformation glucose V glycogen, reduces blood sugar levels, enhances carbohydrate metabolism in muscles, etc. Glucagon is involved in the conversion of glycogen into glucose in the liver, resulting in increased blood sugar levels.
D cellssecrete a hormone somatostatin. Somatostatin inhibits the production of growth hormone by the pituitary gland, as well as the release of insulin and glucagon by α- and β-cells.
At insufficient secretion of hormones by the gland develops diabetes mellitus With this disease, tissues do not absorb glucose, its content in the blood and excretion in the urine increases.
Endocrine part of the gonads
Sex glands(testis and ovary) produce sex hormones. IN testes male sex hormones are produced - androgens: (testosterone n) and androsterone. Androgens affect embryonic differentiation and development of the genital organs, puberty, spermatogenesis, development of secondary sexual characteristics, and sexual behavior. These hormones stimulate protein synthesis and accelerate tissue growth.
Female sex hormones are synthesized in the ovary - estrogens(folliculin) And progesterone, which is produced by the cells of the corpus luteum. In addition, small amounts of androgens are produced in the ovaries. Estrogens influence the development of the external genitalia, secondary sexual characteristics, growth and development of the musculoskeletal system, ensuring the development of the body according to the female type. Progesterone prepares the uterine mucosa for implantation of the embryo, affects the development of the placenta and mammary glands, delays the development of new follicles, etc.
Pineal gland
pineal body, or pineal gland of the brain, part of the diencephalon (epithalamus) also performs endocrine functions. The epiphysis is located in the groove between the superior colliculi of the midbrain quadrigeminal. Its mass is about 0.2 g.
The pineal gland secretes a hormone melatonin, inhibiting the action of gonadotropic hormones. The secretion of the pineal gland changes depending on the light: light inhibits the synthesis of melatonin. The effect of light is realized with the participation of the hypothalamus.
The pineal gland regulates the function of the gonads and puberty. After removal of the epiphysis, premature puberty occurs.
Questions for self-control
1. What systems regulate the physiological functions of the body?
2. How is humoral regulation carried out?
3. Which glands are called endocrine?
4. What are hormones?
5. What are the characteristics of hormones?
6. In what processes are hormones involved?
7. What occurs with hyper- and hypofunction of the endocrine glands?
8. Which glands depend on the pituitary gland?
9. Which glands do not depend on the pituitary gland?
10. What is the highest center for the regulation of endocrine functions?
11. What is the structure of the pituitary gland?
12. What hormones are produced by the anterior pituitary gland?
13. What diseases occur with hyper- and hypofunction of somatotropic hormone of the anterior pituitary gland?
14. What hormones are produced by the intermediate lobe of the pituitary gland?
15. Where are neurohypophysis hormones produced?
16. Where is the thyroid gland located?
17. What hormones does the thyroid gland produce?
18. What do thyroid hormones affect?
19. What diseases occur with hyper- and hypofunction of the thyroid gland?
20. Where are the parathyroid glands located?
21. What hormone do the parathyroid glands secrete?
22. Where are the adrenal glands located?
23. What hormones are produced in the adrenal cortex?
24. What do glucocorticoids affect?
25. What do mineralocorticoids regulate?
26. What do adrenal sex hormones influence?
27. What occurs with hyper- and hypofunction of the adrenal cortex?
28. What hormones are produced by the adrenal medulla?
29. What is the endocrine part of the pancreas represented by?
30. What cells produce insulin?
31. What cells produce glucagon?
32. In what processes are insulin and glucagon involved?
33. What cells secrete somatostatin?
34. What disease develops with insufficient insulin secretion?
35. What hormones are produced in the testes?
36. What hormones are produced in the ovaries?
37. What processes are affected by female hormones?
38. What processes are affected by male hormones?
39. Where is the pineal gland located?
40. What hormones does the pineal gland secrete?
41. What functions is it involved in regulating?
Keywords of the topic “Endocrine glands”
Islet D cells
adenohypophysis
adrenalin
adrenocorticotropic hormone
islet α cells
acromegaly
aldosterone
amino acids
androgens
androsterone
Graves' disease
biological activity
bronze disease
vasopressin
Islet β cells
gigantism
hydrocortisone
hyperfunction
hypothalamus
pituitary
hypofunction
glycogen
glucagon
glucose
glucocorticoids gonadotropic hormone hormones
endocrine glands
corpus luteum
insulin
calcium
dwarf
corticosterone cortex cretinism lipotropin
luteinizing hormone
melanin
melanocytropin
melatatin
metabolism
myxedema
mineralocorticoids
medulla
adrenal glands
neurohypophysis
neurohumoral regulation
neuron
neurosecret
neuroendocrine system nerve impulses norepinephrine oxytacin basal metabolism islets of Langerhans parathyroid hormone parathyroid glands peptides
pancreas
gonads
progesterone
prolactin
goggle-eyed
thyrocalcitonin
growth hormone
diabetes mellitus
secret
testis
mucous tissue swelling
somatostatin
specificity of action
steroid hormones
testosterone
thyroid-stimulating hormone
thyroxine
tropic hormones
triiodothyronine
carbohydrates
follicle stimulating hormone phosphorus
thyroid gland
endocrine glands
pineal gland
estrogens