Hormones and the Endocrine System

16.4 Endocrine System – Concepts of Biology

The endocrine system produces hormones that function to control and regulate many different body processes. The endocrine system coordinates with the nervous system to control the functions of the other organ systems. Cells of the endocrine system produce molecular signals called hormones. These cells may compose endocrine glands, may be tissues or may be located in organs or tissues that have functions in addition to hormone production. Hormones circulate throughout the body and stimulate a response in cells that have receptors able to bind with them. The changes brought about in the receiving cells affect the functioning of the organ system to which they belong. Many of the hormones are secreted in response to signals from the nervous system, thus the two systems act in concert to effect changes in the body.

Endocrine Glands

The endocrine glands secrete hormones into the surrounding interstitial fluid; those hormones then diffuse into blood and are carried to various organs and tissues within the body. The endocrine glands include the pituitary, thyroid, parathyroid, adrenal glands, gonads, pineal, and pancreas.

The pituitary gland, sometimes called the hypophysis, is located at the base of the brain (Figure 16.13a). It is attached to the hypothalamus. The posterior lobe stores and releases oxytocin and antidiuretic hormone produced by the hypothalamus. The anterior lobe responds to hormones produced by the hypothalamus by producing its own hormones, most of which regulate other hormone-producing glands.

Figure 16.13 (a) The pituitary gland sits at the base of the brain, just above the brain stem. (b) The parathyroid glands are located on the posterior of the thyroid gland. (c) The adrenal glands are on top of the kidneys. d) The pancreas is found between the stomach and the small intestine. (credit: modification of work by NCI, NIH)

The anterior pituitary produces six hormones: growth hormone, prolactin, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone. Growth hormone stimulates cellular activities like protein synthesis that promote growth. Prolactin stimulates the production of milk by the mammary glands. The other hormones produced by the anterior pituitary regulate the production of hormones by other endocrine tissues (Table 16.1). The posterior pituitary is significantly different in structure from the anterior pituitary. It is a part of the brain, extending down from the hypothalamus, and contains mostly nerve fibers that extend from the hypothalamus to the posterior pituitary.

The thyroid gland is located in the neck, just below the larynx and in front of the trachea (Figure 16.13b). It is a butterfly-shaped gland with two lobes that are connected. The thyroid follicle cells synthesize the hormone thyroxine, which is also known as T₄ because it contains four atoms of iodine, and triiodothyronine, also known as T₃ because it contains three atoms of iodine. T₃ and T₄ are released by the thyroid in response to_{thyroid-stimulating hormone produced by the anterior pituitary, and both T3 and T4 have the effect of stimulating metabolic activity in the body and increasing energy use. A third hormone, calcitonin, is also produced by the thyroid. Calcitonin is released in response to rising calcium ion concentrations in the blood and has the effect of reducing those levels.}

Most people have four parathyroid glands; however, the number can vary from two to six. These glands are located on the posterior surface of the thyroid gland (Figure 16.13b).

The parathyroid glands produce parathyroid hormone. Parathyroid hormone increases blood calcium concentrations when calcium ion levels fall below normal.

The adrenal glands are located on top of each kidney (Figure 16.13c). The adrenal glands consist of an outer adrenal cortex and an inner adrenal medulla. These regions secrete different hormones.

The adrenal cortex produces mineralocorticoids, glucocorticoids, and androgens. The main mineralocorticoid is aldosterone, which regulates the concentration of ions in urine, sweat, and saliva. Aldosterone release from the adrenal cortex is stimulated by a decrease in blood concentrations of sodium ions, blood volume, or blood pressure, or by an increase in blood potassium levels. The glucocorticoids maintain proper blood-glucose levels between meals. They also control a response to stress by increasing glucose synthesis from fats and proteins and interact with epinephrine to cause vasoconstriction. Androgens are sex hormones that are produced in small amounts by the adrenal cortex. They do not normally affect sexual characteristics and may supplement sex hormones released from the gonads. The adrenal medulla contains two types of secretory cells: one that produces epinephrine (adrenaline) and another that produces norepinephrine (noradrenaline). Epinephrine and norepinephrine cause immediate, short-term changes in response to stressors, inducing the so-called fight-or-flight response. The responses include increased heart rate, breathing rate, cardiac muscle contractions, and blood-glucose levels. They also accelerate the breakdown of glucose in skeletal muscles and stored fats in adipose tissue, and redirect blood flow toward skeletal muscles and away from skin and viscera. The release of epinephrine and norepinephrine is stimulated by neural impulses from the sympathetic nervous system that originate from the hypothalamus.

The pancreas is an elongate organ located between the stomach and the proximal portion of the small intestine (Figure 16.13d). It contains both exocrine cells that excrete digestive enzymes and endocrine cells that release hormones.

The endocrine cells of the pancreas form clusters called pancreatic islets or the islets of Langerhans. Among the cell types in each pancreatic islet are the alpha cells, which produce the hormone glucagon, and the beta cells, which produce the hormone insulin. These hormones regulate blood-glucose levels. Alpha cells release glucagon as blood-glucose levels decline. When blood-glucose levels rise, beta cells release insulin. Glucagon causes the release of glucose to the blood from the liver, and insulin facilitates the uptake of glucose by the body’s cells.

The gonads—the male testes and female ovaries—produce steroid hormones. The testes produce androgens, testosterone being the most prominent, which allow for the development of secondary sex characteristics and the production of sperm cells. The ovaries produce estrogen and progesterone, which cause secondary sex characteristics, regulate production of eggs, control pregnancy, and prepare the body for childbirth.

There are several organs whose primary functions are non-endocrine but that also possess endocrine functions. These include the heart, kidneys, intestines, thymus, and adipose tissue. The heart has endocrine cells in the walls of the atria that release a hormone in response to increased blood volume. It causes a reduction in blood volume and blood pressure, and reduces the concentration of Na⁺ in the blood.

The gastrointestinal tract produces several hormones that aid in digestion. The endocrine cells are located in the mucosa of the GI tract throughout the stomach and small intestine. They trigger the release of gastric juices, which help to break down and digest food in the GI tract.

The kidneys also possess endocrine function. Two of these hormones regulate ion concentrations and blood volume or pressure. Erythropoietin (EPO) is released by kidneys in response to low oxygen levels. EPO triggers the formation of red blood cells in the bone marrow. EPO has been used by athletes to improve performance. But EPO doping has its risks, since it thickens the blood and increases strain on the heart; it also increases the risk of blood clots and therefore heart attacks and stroke.

The thymus is found behind the sternum. The thymus produces hormones referred to as thymosins, which contribute to the development of the immune response in infants. Adipose tissue, or fat tissue, produces the hormone leptin in response to food intake. Leptin produces a feeling of satiety after eating, reducing the urge for further eating.

Endocrine Glands and Their Associated Hormones

Table 16.1

Chemical Exposures and Our Endocrine System

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The human endocrine system produces hormones that help regulate bodily functions, including metabolism, growth, development, tissue function, sexual function, reproduction, sleep and mood. Made up of the pituitary, thyroid, parathyroid and adrenal glands, as well as the pancreas, ovaries (in females) and testicles (in males), the endocrine system is at work virtually all the time. Our bodies rely on hormones to manage many normal daily functions, as well as ongoing growth and developmental changes throughout our lives.

Given the importance of endocrine activity to our overall health, it’s understandable that readers may become concerned by posts on popular social media sites that claim exposures to some chemicals may have lasting health impacts on their body.

The terms “endocrine-disrupting chemical” or “hormone-disrupting chemical” are widely misused and considered by scientists to be a misnomer, since many substances have been shown to interact with the endocrine system without causing an adverse health effect. Many things we come in contact with, such as sunlight, or common substances, such as caffeine, can “activate” the endocrine system. Some of these interactions are harmless. Others are helpful — like when exposure to sunlight causes our bodies to produce Vitamin D.

What is an endocrine disruptor?

In order for a chemical to be an “endocrine disruptor,” it must affect the endocrine system in a way that causes a negative health effect. It’s important to distinguish endocrine activity that is disruptive or damaging, from endocrine activity that is neutral or even essential to our well-being.

Not all chemicals that interact with the endocrine system present a risk of harm – in many instances, the body naturally adjusts and there is no health effect. For example, when we drink a soy latte or eat edamame, our estrogen levels will become slightly elevated, and then return to normal after a short time. Just because a substance is endocrine active does not mean that it is endocrine disruptive.

So how do we look beyond the headlines, to understand the science? Some chemicals, both natural and man-made, can and do interact with the endocrine system. There is confusion as to whether this interaction is itself harmful, or if the endocrine activity could lead to harm if exposure is above a certain level or frequency.

The two articles on the right explore 1) the science of how our bodies are exposed to and metabolize substances, as well as 2) public policy developments – how government regulators study and screen substances to understand if they might be endocrine active or endocrine disrupting.

The goal is to enable regulators to use science to reasonably assess real-life risk – the possibility of harm arising from a particular exposure to a specific chemical, under typical conditions. In doing so, scientists can help provide informed and confident recommendations to regulatory decision-makers about how chemical ingredients can be safely used as a part the products and materials in our everyday lives.

How Do Chemicals Impact the Endocrine System? Learn more here.

Biology4Kids.com: Animal Systems: Endocrine System

The endocrine system is one of the more difficult systems that you will learn about in class. Most of the activities of the system are not seen and you probably don’t know that anything is happening. You definitely won’t see any obvious problems, only the results of problems. Most of the early information about the endocrine system came from studying things that went wrong with the system.

Even today, there are still many mysteries related to this system and it’s activities. The best description we can offer is to describe the endocrine system as the chemical brother of the nervous system. While the nervous system transmits information and instructions using electricity, the endocrine system transmits information with chemicals and biological compounds.

This system controls many of the biochemical pathways that occur in your body. The core tool used by the endocrine system is a compound called a hormone. Your body uses dozens of hormones to regulate your growth, digestion, body temperature, and glucose metabolism (to name a few). A hormone released by an endocrine gland can travel throughout the body and change the activity of cells from many other systems. The endocrine system is also unique in that it uses glands and cells within organs that are all closely related to other systems.

We don’t know where to begin the discussion of endocrine interaction with other systems. The endocrine system is everywhere and the chemicals produced by the system act in a variety of ways on every cell of your body. The circulatory system is the transport system for endocrine information. While the nervous system uses neurons, the endocrine chemicals and hormones must circulate through the body via blood vessels.

Many glands in your body secrete hormones into the blood. You have a pituitary gland in the base of your skull that releases hormones that control blood pressure and your excretory system. You have a thyroid gland in your neck that controls your bone growth rate and metabolism. You even have a tiny little adrenal gland above your kidneys that releases adrenalin if you get excited. Endocrine glands are everywhere.

Because our endocrine system is very delicate, many things can go wrong. An extreme example is if a gland stops working, but they are more likely to work more or less than they should. If you don’t get enough iodine in your food, your thyroid gland can have big problems and grow to the size of a baseball called a goiter. Other common problems with your thyroid can increase your body’s metabolism and make you jumpy and sweaty (hyperthyroidism) or decrease the levels and make you sluggish (hypothyroidism). Some individuals have a problem making insulin in their pancreas. Those individuals have a disease called diabetes and they are not able to metabolize carbohydrates correctly. They must often take injections of insulin to counteract the problem.

Communicating Bacteria Fight Disease (US-NIH Video)

Useful Reference Links

Encyclopedia.com (Endocrinology):
http://www.encyclopedia.com/topic/Endocrinology.aspx
Wikipedia:
http://en.wikipedia.org/wiki/Endocrine_system
Encyclopædia Britannica:
http://www.britannica.com/EBchecked/topic/186893/human-endocrine-system

Endocrine system | HealthEngine Blog

Introduction to the endocrine system

The role of the endocrine system is to maintain the body in balance through the release of hormones (chemical signals) directly into the bloodstream. Hormones transfer information and instructions from one set of cells to another. Many different hormones move through the bloodstream, but each type of hormone is designed to affect only certain cells.
A gland is a group of cells that produces and secretes chemicals. A gland selects and removes materials from the blood, processes them, and secretes the finished chemical product for use somewhere in the body. The endocrine gland cells release a hormone into the blood stream for distribution throughout the entire body. These hormones act as chemical messengers and can alter the activity of many organs at once.
The parts of the endocrine system are grouped together because they release hormones into the blood without going through a duct (which is basically a tube) first. This is different to an exocrine gland, which releases what it creates through a tube to somewhere other than the blood.
Hormones can act on some specific cells because they themselves do not actually cause an effect. It is only through binding with a receptor (part of the cell specifically designed to recognize the hormone) like a key into a lock – that causes a chain reaction to occur, changing the activity of the cells. If a cell does not have a receptor for a hormone then there will be no effect. Also, there can be different receptors for the same hormone, and so the same hormone can have different effects on different cells.

The pituitary gland

The pituitary gland is a small, oval gland lying at the base of the brain. It is divided into two sections – an anterior (meaning front) and posterior (meaning back) part because they are formed in different ways. The anterior pituitary is a collection of hormone-producing cells. The release of the hormones by these cells is controlled by a region of the brain called the hypothalamus
The posterior pituitary is made up of around 50,000 nerve endings. These nerves release their hormones straight into the blood.
Numerous hormones are released from the anterior pituitary. They are:

• Thyroid-stimulating hormone (TSH): This stimulates the thyroid gland.
• Adrenocorticotrophic hormone (ACTH): This stimulates the adrenal glands.
• Follicle-stimulating hormone (FSH): Promotes development of eggs within the ovaries and stimulates the secretion of oestroges (the primary female hormone). In men, FSH is important for sperm production in the testes.
• Luteinizing hormone (LH): Causes ovulation in women and prepares the uterus for pregnancy.
• Prolactin (PRL): Prolactin causes the development of breast tissue and the production of milk.
• Growth hormone (GH): Also called Somatotropin, it causes growth in almost all tissues in the body that are capable of growing. It promotes both an increase in cell size, and cell number.

Those hormones released from the posterior pituitary are:

• Anti-diuretic hormone (ADH): ADH causes the kidneys to keep more water in the body.
• Oxytocin: This causes contractions in the uterus of a pregnant woman and also causes the release of milk from the breast

The thyroid gland

The thyroid (meaning ‘shield-shaped’) gland sits in the centre of the neck, a the front, below the Adam’s apple. It is made of two lobes joined in the centre. At 15 to 20 grams it is one of the largest of the endocrine glands.
The thyroid secretes two major hormones called thyroxine (T₄) and triiodothyronine (T₃). They cause lots of things, but mostly they increase the rate of metabolism in the body. Metabolism is the amount of energy used by the body. An increase means more energy sources like fats and sugars are being broken down, and the body is using more energy to grow. The thyroid is controlled mainly by the release of Thyroid Stimulating Hormone (TSH) from the pituitary gland. The thyroid also secretes a hormone called calcitonin, important in keeping calcium levels in the body normal.
To create the thyroid hormones, the body needs a substance called iodine, which is found mainly in salt.
Low levels of thyroid hormone can result in feelings of tiredness, excessive sleep, loss of sex-drive, and smaller, less frequent periods in a woman.
Calcitonin is another thyroid hormone and this assists in the regulation of calcium concentration in body. Calcitonin lowers plasma calcium levels by inhibiting the cells which break down bone, and stimulating calcium excretion by the kidneys.

The parathyroid glands

The parathyroid glands are small, ovoid, and lie on the back of the thyroid gland. Most people have four parathyroid glands, two at the top, and two at the bottom.
There are two types of cell within the parathyroid gland. While calcitonin is released from the thyroid when calcium levels are too high, the parathyroids release their hormone when calcium levels are too low.

The thymus

The thymus is located in the lower part of the neck, and the front part of the upper chest. After puberty it is mostly replaced by fat.
While the thymus does not play a big role, it does produce several hormones important in the development and maintenance of a normal immune system.

The adrenal glands

The adrenal glands (also known as the suprarenal glands) are yellow, pyramid-shaped glands located at the top of the kidneys. They usually weigh roughly 7.5g and are heavier in men than women. Each adrenal gland has two parts: an adrenal medulla (inside), and an adrenal cortex (outside).
The adrenal cortex is the outer layer and secretes corticosteroids and male sex hormones which are derived from cholesterol and various other fats, hence their yellowish colour. It is divided into three distinct zones, each producing different hormones.
The adrenal medulla is reddish-brown and the cells here are like nerve cells and are activated by the nervous system. The cell types of this region are are known as pheochromocytes, or chromaffin cells.
Three major types of hormones are released from the adrenal cortex. These are mineralocorticoids, glucocorticoids and a small amount of sex hormones.
Mineralocorticoids are called as such due to their effects on the electrolytes (or minerals) of the body, as well as the level of water. Glucocorticoids control sugar (glucose) levels.
There are two horomes produced in the cortex of great importance and they are aldosterone, the major mineralocorticoid and cortisol, the major glucocorticoid.

Cortisol
Cortisol is a ‘stress hormone’ and is released in times when the body needs increased energy. It is stimulated for release by Adrenocorticotrophic hormone (ACTH), mentioned earlier as being released from the pituitary gland which can be caused by any stressful event.
Cortisol causes the liver to release more sugar, causes breakdown of muscle and fat for energy and also lowers the amount of energy used by the cells of the body. It is also anti-inflammatory and lowers the body’s ability to protect itself.

Aldosterone
Aldosterone causes the body to try and keep water and sodium in the body by acting on the kidney.
The adrenal medulla (the centre) secretes adrenaline, and noradrenaline. The secretion of these hormones is because of the need for quick bursts of energy. Their secretion triggers cellular energy use and allows access to the body’s energy reserves. These effects are very rapid and occur within roughly thirty seconds, and staying there for several minutes. The circulating adrenaline also causes constriction of virtually every vessel in the body (causing your hands to go pale), increased activity of the heart (making it beat faster), inhibition of the gastrointestinal tract (giving you butterflies) and dilation of the pupils of the eyes.

The pancreas

The pancreas is a pinkish-grey organ that lies behind to the stomach. The organ is approximately 15cm in length with a long, slender body connecting the head and tail segments.
The endocrine pancreas is separate from the exocrine pancreas which is discussed under the gastrointestinal section. The endocrine pancreas is made up of small clumps of cells within the pancreas, called pancreatic islets, or the islets of Langerhans. These account for only 1% of the pancreatic mass. It is composed of three distinct cell types each producing a different hormone. The two important hormones are:

Glucagon
Secretion of glucagon is controlled by the level of blood sugar, being released when levels are too low. This greatly increases the output of sugar from the liver and returns blood sugar levels to normal.

Insulin
Insulin is designed to lower blood sugar levels when they become too high and is released in periods when there is a lot of sugar available, like after a meal. A lack of insulin means the body has to use fat for metabolism rather than sugar and can lead to a condition known as ketoacidosis.

The pineal gland

The pineal gland is a small, red, pinecone-shaped structure in the brain.
The pineal gland secretes a substance called melatonin. Melatonin slows the maturation of sperm, eggs and reproductive organs by stopping the production of FSH and LH (mentioned earlier). Melatonin also appears to play a role in regulating the ‘circadian rhythms’ of the body, which influence the day-night cycle. It is also a powerful antioxidant and protects the brain from toxins.

References

1. Guyton AC, Hall JE. Textbook of Medical Physiology. Philidelphia: Harcourt Health Sciences; 2000.
2. Martin EA (ed). Concise Medical Dictionary. Oxford: Corgi Books; 1982.
3. Martini FH. Human Anatomy (third edition). New Jersey: Prentice-Hall; 2000.
4. Moore KL, Dalley AF. Clinically Oriented Anatomy (fourth edition). Baltimore: Lippincott Williams & Wilkins; 1999.
5. Nolte J. The Human Brain: An Introduction to its Functional Anatomy (fifth edition). St Louis: Mosby; 2002.

The Role of Endocrine System in the Inflammatory Process

Inflammation is a general tissue response to a wide variety of stimuli. In situations in which inflammation is not properly regulated, inflammatory response may be exaggerated or ineffective, leading to immune dysfunction, recurrent infections, and tissue damage, both locally and systemically. Various hormones, cytokines, vitamins, metabolites, and neurotransmitters are known to be key mediators of the immune and inflammatory responses in endocrine as well as in paracrine fashions. Therefore, exploring the mechanisms underlying the production and response to these mediators might broaden the horizons for the development of novel therapeutic options that target disease states in which the immune/inflammatory responses are compromised or dysregulated.

This special issue covers the most current research aimed at elucidating the cellular and molecular mechanisms underpinning the endocrine/paracrine networks of regulatory immune mediators and their targets.

In this journal edition in disease states, Y.-S. Lee and H.-S. Jun reviewed the current status of glucagon-like peptide-1- (GLP-1-) based therapies and their impact on the treatment and management of type 2 diabetes mellitus. GLP-1 is an incretin hormone mainly secreted by intestinal L cells in response to nutrient ingestion, which has beneficial effects for glucose homeostasis by stimulating insulin secretion from pancreatic beta-cells, delaying gastric emptying, decreasing plasma glucagon, reducing food intake, and stimulating glucose catabolism. Beyond their metabolic effects, it is reviewed herein that GLP-1-based therapies have displayed anti-inflammatory properties through promoting downregulation of proinflammatory responses in a cell-autonomous as well as a systemic manner, especially in the context of inflammation-related diseases.

A. Mancini et al. report in this issue that thyroid hormones play particularly important roles in the antioxidant balance, since both hyper- and hypothyroidism have been shown to be associated with oxidative stress (OS) in humans and animals. In this context, the pathophysiological mechanisms of the nonthyroidal illness syndrome (NTIS) typically manifest as reduced conversion of thyroxine (T4) to triiodothyronine (T3) in several acute and chronic systemic conditions. This syndrome, along with the deiodinases that catalyze the conversion of T4 to T3, is reviewed herein.

Female development and reproductive function is well documented to be modulated by estrogens. In particular, 17β-estradiol (E2) is the main sex hormone regulating reproduction in females. However, E2 is also deeply involved in several other pathologies, such as cancer and autoimmune and infectious diseases, in which the innate immune response is a key player. I. Medina-Estrada et al. reported in this issue that E2 induces anti-inflammatory responses of bovine mammary epithelial cells during S. aureus internalization and that effect is dependent, at least in part, on the estrogen receptor α (ESRα).

Like estradiol, progesterone levels fluctuate dramatically during pregnancy. In this issue, M. Wu et al. report that the known increase in serum progesterone levels during pregnancy exacerbates gingival inflammation. This effect of progesterone is shown to be independent of crevicular fluid levels of both interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α).

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and is a leading cause of blindness across the globe. Genetic predisposition has been found to contribute to DR pathology, since specific haplotypes cosegregate with disease onset within affected families. M. M. Yang et al. reported herein that a polymorphism in the C5 gene (rs17611) represents a novel putative susceptibility locus for DR, particularly predisposing to the clinically relevant proliferative DR subtype. On the other hand, it was shown that polymorphism of SERPING1, which encodes for one well-known component of the Complement system, has only marginal to no contribution to the development of DR.

Endoplasmic reticulum (ER) stress facilitates fibrotic remodeling through the promotion of inflammatory responses. Aldosterone (Aldo), a known ER stressor, is thought to be involved in fibrotic renal injury by upregulating the production of inflammatory mediators such as IL-1β and IL-6. H. Guo et al. reported an important role for Aldo responses in ER stress and renal inflammation in the pathogenesis of renal fibrosis. In addition, the ER stress can be inhibited by Tauroursodeoxycholic Acid (TUDCA) and this effect is associated with downregulation of collagen I, collagen IV, fibronectin, transforming growth factor-β (TGF-β) expression, and Nlrp3 inflammasome markers such as the apoptotic speck protein (ASC), IL-1β, and IL-18. Altogether, these findings suggest that these inflammatory pathways are involved in Aldo-induced chronic kidney disease.

In summary, the original research articles and literature reviews featured in this special issue will hopefully enhance our knowledge about the roles of the endocrine system in the inflammatory process, shedding light on potential avenues for the development of novel therapies.

Acknowledgments

We would like to thank the authors and reviewers for their valuable contributions to this special issue.

Christian Bowman-Colin
Luis A. Salazar
Joilson O. Martins

Copyright

Copyright © 2016 Christian Bowman-Colin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Hormones and the Endocrine System

90,000 their structure, functions that produce

“The glands of fear and courage”, “fighters of the endocrine system” – such a contrasting metaphor in relation to these organs is quite understandable, because it is they who are directly involved in the formation of two basic human emotions – fear and anger. What are the adrenal glands, what is their role in the body, where are they located? Let’s try to figure it out.

Having attracted the attention of scientists for a long time, these endocrine glands were first described by the outstanding Italian physician and anatomist Bartolomeo Eustachius in the middle of the 16th century.Currently, science has detailed information about the structure and functions of the adrenal glands, but we probably do not know everything about them.

How are the adrenal glands arranged?

There are two adrenal glands (aka adrenal glands) in the human body. They are located in the retroperitoneal space in the lumbar region, and are small “caps” over the kidneys. Despite the fact that the role of the adrenal glands is the same, they have a different shape. The gland on the left is visually similar to a crescent, and the right one resembles a triangle.

Adrenal gland structure

Outside, the glands are covered with a connective tissue capsule. Looking at the cross-section of the gland, you can find two layers in it. The first is located on the periphery of the organ and is called the cortex. In the central region of the gland is the medulla.

To answer the question of which glands the adrenal glands belong to, it is enough to refer to their structure. The adrenal glands produce biologically active substances – hormones that go directly into the blood.The adrenal glands do not have excretory ducts, therefore these organs are referred to as endocrine glands.

The cortical substance makes up about 90% of the total mass of the glands. It is formed by cells that produce corticosteroid and sex hormones.

Three zones are distinguished in the cortical layer, differing from each other in the structure of their constituent cells.

1. Glomerular – occupies about 15% of the entire cortex. It consists of small cells collected in “glomeruli” and synthesizing mineralocorticoids – aldosterone, corticosterone, deoxycorticosterone.These hormones are involved in the regulation of blood pressure and water-salt balance.

2. Bundle – its structure is made up of long bundles of large cells that occupy two-thirds of the adrenal cortex. They produce glucocorticoids – hormones that affect immunity, suppress the growth of connective tissue, and also reduce the intensity of inflammatory, allergic reactions in the body. These include, in particular, cortisol and cortisone.

3. Mesh – consists of a thin layer of small cells of various shapes, forming a mesh structure.Here the formation of sex hormones occurs – androstenedione, DEASO4, which are responsible for the development of secondary sexual characteristics of a person, are important for bearing a fetus.

The medulla, located in the center of the adrenal glands, consists of chromaffin cells. Despite a small share in the total volume of the glands, it is the cells of the medulla that produce catecholamines – adrenaline and norepinephrine – which control the body’s work under stress.

What do we need the adrenal glands for?

For life.And these are not pompous words. The absolute importance of the adrenal glands is confirmed by the fact that when they are damaged or removed, death occurs.

The formation of hormones and biologically active substances that directly affect the growth, development and functioning of vital organs is the main function of the adrenal glands. Thanks to hormones produced by the adrenal medulla and cortex, various metabolic processes are regulated. In addition, they take part in the body’s immune defense, human adaptation to adverse external conditions and changing internal factors.

Today there are more than 50 known steroid compounds produced only by the adrenal cortex. For example, hydrocortisone ensures the accumulation of glycogen in the liver and muscles, inhibits protein synthesis in some tissues and accelerates its formation in others. It also affects the metabolism of fats, inhibits the activity of lymphoid and connective tissues. Aldosterone is responsible for the regulation of water-salt metabolism, maintaining the ratio of sodium and potassium salts.

Cortisol stimulates the immune system.If the body is exposed to unforeseen stress, then this hormone is urgently produced. Thanks to it, the work of the brain improves, the heart muscle is strengthened, the body acquires the ability to withstand various types of stress.

The amount of adrenaline and norepinephrine, which are produced by cells of the adrenal medulla, usually increases in stressful situations. Increasing the level of adrenaline in the blood helps to start the processes that mobilize the body and make it capable of surviving in adverse conditions.At the same time, breathing becomes more frequent, the flow of oxygen to the tissues accelerates, the level of sugar in the blood rises, the tone of the blood vessels and pressure. Due to the stimulating effect of these hormones, muscle strength, reaction speed, endurance and pain threshold increase. This allows you to respond to the threat with one of the options – “fight” or “flight”.

By regulating vital functions, the adrenal glands help us quickly adapt to changes in the environment. To reduce the risks of adrenal dysfunction, you should, if possible, avoid stress, be physically active, observe a work and rest regimen, eat right and consult a doctor in a timely manner when complaints appear and for preventive purposes.

The editors recommend:

Neighboring the thyroid gland: what are the parathyroid glands?

90,000 Pituitary gland. Epiphysis. Adrenal glands. Thymus is a lesson. Biology, Human (grade 8).

The main role in the functioning of the endocrine system is played by hypothalamus , pituitary gland and adrenal glands . These glands regulate the course of processes that ensure the interaction of all parts of our body. The highest subcortical center of endocrine regulation is the hypothalamus – the medulla oblongata.It releases neurohormones that stimulate the pituitary gland.

The pituitary gland is an endocrine gland that regulates the activity of many other endocrine glands (and, accordingly, human organs).

This gland is the size of a pea (the mass of the pituitary gland in an adult \\ (0.6 \\) – \\ (1.1 \\) g), located at the base of the brain, consists of three lobes (anterior, posterior and middle ).

The anterior pituitary gland secretes hormones ( tropic hormones ) that affect the growth and function of other endocrine glands.These hormones regulate the functions of:

• thyroid gland ( thyroid stimulating hormone ),
• gonads ( gonadotropic hormone ),
• adrenal cortex ( adrenocorticotropic hormone – ACTH ).

Another of the hormones of the anterior pituitary gland – growth hormone , or somatotropic hormone – regulates the growth of bones in length, accelerates metabolism. With its deficiency , the child’s growth slows down, dwarfism develops (the proportions of the body and the mental development of a person are not disturbed).

An increase in the content of growth hormone in a child’s body causes its increased growth and leads to gigantism .

When an excess amount of growth hormones is released into the blood in an adult, when bone growth is complete, the disease acromegaly develops. In such patients, the bones of the fingers, feet, and the facial part of the skull are enlarged. At the same time, the nose and chin grow vigorously, the tongue, the volume of the heart and other organs increase.The vocal cords thicken and the voice becomes rough.

The pituitary gland secretes hormones that stimulate the growth and maturation of germ cells, the formation and secretion of milk by the mammary glands, and also affect the water-salt metabolism in the body.

The secretion of pituitary hormones into the blood is regulated according to the principle of feedback (self-regulation): a decrease in the content of a certain hormone in the blood causes the pituitary gland to release the corresponding hormone, which increases the activity of the gland.

The posterior lobe of the pituitary gland releases two hormones into the blood:

• hormone vasopressin enhances the process of reabsorption, i.e. the reabsorption of water in the renal tubules. With a lack of this hormone, a lot of urine is formed and diabetes insipidus develops.
• The hormone oxytocin acts on smooth muscles and causes them to contract. This hormone is produced during childbirth; it stimulates the contraction of the walls of the uterus and the release of milk from the mammary glands in lactating women.

In the middle lobe of the pituitary gland , melanotropic hormone is produced, which affects the formation of melanin pigment in skin cells and determines its color.

Epiphysis ( pineal gland ) – refers to the brain and regulates the biological rhythms of the body (daily, seasonal, etc.). It produces a hormone that inhibits premature puberty. The release of the hormone depends on the light.

The adrenal glands are located at the upper poles of the kidneys and look like flattened pyramids.

Each adrenal gland consists of the outer, cortical, and inner, medullary layers.

The adrenal cortex produces more (40) hormones that affect metabolism, regulate mineral and water metabolism. The adrenal glands also produce sex hormones.

The adrenal medulla produces the hormone adrenaline (when the body is exposed to strong stressful stimuli, such as fear).

Adrenaline increases the excitability of the nervous system, increases the heart rate, affects the lumen of blood vessels (dilates the vessels of the heart), increases blood flow in the liver, muscles, brain, reduces muscle fatigue.

The adrenal glands also produce the hormone norepinephrine , which plays the role of a neurotransmitter in synapses. Norepinephrine increases arteriole tone and blood pressure.

Thymus (thymus gland)

Thymus (thymus gland) is placed behind the sternum and is developed in newborns.Its hormones affect immunity, regulate the function of other endocrine glands: inhibit the activity of the thyroid gland, delay the body’s puberty.
In adults, the thymus atrophies. In this gland, differentiation and multiplication of cells – precursors of T-lymphocytes occurs, the hormone thymosin regulates carbohydrate metabolism and calcium metabolism, affects the regulation of neuromuscular transmission.

The role of the nervous endocrine system in inflammation

: – regulates tone
(blood circulation) – regulates trophism
fabrics.In Speransky’s laboratory:
chronic irritation of the nervous system
leads to the formation of multiple
inflammatory lesions; if blocked
receptors, the inflammation subsides.
sympathetic nervous system inhibits
inflammation, irritation of the parasympathetic
nervous system increases inflammation.
cerebral cortex: positive
emotions activate phagocytosis
hibernation, hypothermia, anesthesia weaken
intensity of inflammation.
System: Trigger
compensatory and adaptive
reactions. Role
endocrine system
in inflammation: Pro-inflammatory
hormones: growth hormone (STH)
aldosterone mineralocorticoids
hormones: glucocorticoids ACTH Cortisone:
delays the development of edema, stabilizes
lysosomal membranes
the focus is a source of pathological
impulses leading to the development
general phenomena: changes in internal
organs change neuro-endocrine
regulation (feedback) intoxication shifts
protein composition of blood
leukocytosis fever pain acceleration
ESR activation of reticuloendothelial
system change immunological
processes

Theories of inflammation

: Theory
Virchova: the main link of inflammation is
state of the cell
link – a change in blood circulation.Mechanical
theory (Voronin and Shklyarevsky): in
the basis of inflammation – changes in elastic
properties of tissues. Physicochemical theory
(Shade): basic – physical and chemical
shifts in tissues – all these are theories
inflammatory focus.
evolutionary theory of Mechnikov: 1. Evaluation
inflammation from the point of view of a holistic
organism. 2. Introduced a comparative historical
method in the pathology of inflammation. 3. Opened
phagocytosis and created the doctrine of phagocytosis,
as the most important protective reaction
organism. 4. Tied together reactivity
immunity, inflammation.5. laid the foundations
teachings about active mesenchyme. 6. Predicted
opening of lysosomes and lysosomal
enzymes – modern theories
inflammation: Chernukh, Polycarp, etc.
scientists Combining all previous
theories on cellular, subcellular and
molecular levels. Two opposite
sides of inflammation (dual nature
inflammation): I. Damage caused by
Irritant Alteration Disorder
blood circulation II. Protective and adaptive
Emigration phenomena
leukocytes Phagocytosis Leukocytosis Partially
exudation (barrier) proliferation
(barrier) Natural anti-inflammatory
systems (anti-inflammatory hormones)

Allergies and Allergens

Allergy –
…pathologically increased
the sensitivity of the body to
any antigens or haptens,
associated with the restructuring of the immune
systems and accompanying
structural and functional damage
cells (Poryadin G.V.) ._ Allergy (Greek.
allos – other, different + ergos – action) is
typical form of altered immunological
reactivity characterized by
specific, selective
increased sensitivity of the body
to repeated exposure to the allergen (substance
antigenic nature) ._ Allergens
-.these are antigenic and
non-antigenic (hap-ten) nature, as well as
some physical factors (high and
low temperature, ultraviolet
irradiation, ionizing radiation and
etc.) ._ Classification and characterization
allergens: A. By origin and
nature: I. Exogenous allergens
(exoallergens): 1. Food (alimentary). 2.
Medicinal. 3. Pollen. 4. Dusty. 5.
Epidermal. 6. Whey. 7.
Infectious. 8. Household chemical
connections 9. Physical factors. II.
Endogenous allergens (endoallergens,
autoallergens) resulting from: 1.The damaging action of the physical,
infectious and other exogenous factors
with the formation of: a) denatured
proteins of the cell; b) complexes of normal
proteins with exogenous allergens; c)
target cells for the immune system. 2.
Natural immunological disorders
tolerance (violations of histohematological
barriers) B. Along the ways of penetration
allergens to the body: 1. Pneumoallergens. 2.
Alimentary. 3. Contact. 4. Parenteral. 5.
Transplacental ._ Classification
allergic reactions
(according to Gell and Coombs): 1 type – anaphylatoxic
reactions (atopic), or
hypersensitivity to anaphylactic
type, due to reagins (Ig E).Type 2
– cytotoxic reactions, or
hypersensitivity to cytotoxic
type (Ig G and M). 3 type – immunocomplex
reactions, or hypersensitivity,
due to immune complexes.4
type – cellular reactions, or
hypersensitivity slow
type (due to sensitized
T-lymphocytes) .5 type – stimulated
reactions, or stimulated
hypersensitivity (Ig and T-lymphocytes) ._

ALLERGIC
R-TsII IMMEDIATE TYPE,

The value of the endocrine glands for the development of the body

Topic of the lesson: The value of the endocrine glands for the development of the body.

Purpose of the lesson: to form new anatomical and physiological concepts – about the endocrine glands, hormones, their properties and significance in the life of the body.

Tasks :

determine the role of endocrine glands in the functioning of the body;

show the importance of knowledge about hormones for medicine.

Type of occupation: lecture.

Type of lesson: introductory.

Equipment: tables with images of endocrine glands, diagrams.

The main questions of the lecture:

1. The value of the endocrine glands for growth, development and regulation of body functions.

2. Hormones are waste products of the endocrine glands.

3. Hormones are important medicines in our life.

Properties of hormones and their importance in the body.

3. The relationship between the activity of the endocrine glands.

1. Teacher’s story.

Endocrine glands, or endocrine glands, are specialized organs or groups of cells, the main function of which is to produce and release into the internal environment of the body (blood) of specific biologically active substances – hormones.The endocrine glands include: the thyroid gland, pancreas (islets of Langerhans), adrenal glands, sex glands (ovaries and testes), as well as the pituitary gland and pineal gland. (Table 1).

Previously, the pituitary gland was considered the main, the main gland of the human body. The hypothalamus is connected to the pituitary gland by a local network of blood vessels, the so-called pituitary portal system, which delivers blood from the base of the hypothalamus to the anterior pituitary gland. Hypothalamic neurons release their hormones into the blood of this network, and the corresponding cells of the pituitary gland react to these hormones after they are bound by specific surface receptors.

So far, six hypothalamic hormones have been identified that selectively affect the cells of the anterior pituitary gland.

Specific groups of cells in the anterior pituitary gland with the help of hormones control certain endocrine organs located in different areas of the body. Each of these groups of pituitary cells is under the control of stimulating or inhibiting factors secreted by the neurons of the hypothalamus into the pituitary portal circulation system.

ACTH – adenocorticotropic hormone (corticotropin).

CL – corticoliberin.

LL – luliberin.

SL – somatoliberin.

TL – thyroliberin, TSH – thyroid stimulating hormone.

FL – folliberin, FSH – follicle-stimulating hormone.

Since these neurons exert a powerful influence on the pituitary gland, the hypothalamus should be considered the true “main gland” of the endocrine system. The first link in hypothalamic control of the endocrine system is the transmission of hormonal mediators through the pituitary portal system.The same hypothalamic neurons can form other synoptic connections in the brain. In this case, their secretory products act as neurotransmitters.

Table 1.

Neuro-humoral regulation of the functioning of the human body

Secretion of thyroxine

3

Cardiovascular 9203

903.

Exudogenous gland

The activity of all endocrine glands is controlled by two interconnected structures of the brain: the hypothalamus and the pituitary gland.Thus, the nervous system has a direct effect on the production of hormones by the endocrine glands. This relationship between the two most important systems of regulation of the state of our body is especially pronounced under stress.

Everyone experienced stress. However, the meaning of the words “stress”, “success”, “failure”, “happiness” is not the same for different people. For a stress response, it doesn’t matter whether the situation you are faced with is pleasant or not, only the intensity of the need to adapt to it is important.It is not easy to imagine that heat, cold, joy, sadness, any disease cause the same hormonal changes in our body, but this is so.

In response to any effect in the body, a cascade of reactions associated with the action of various hormones is immediately triggered, one of the most famous is adrenaline: pulse, breathing increase, blood pressure rises, pupils dilate, etc. This hormone is one of the first to react to any a stressful situation (not only with fear, but also with positive emotions).It, along with the similar hormone norepinephrine, is secreted from the adrenal glands into the bloodstream and provides the very first and fastest response to stress.

Then other adrenal hormones – corticosteroids (cortisol, corticosterone) – come into play. Thanks to their action, the level of the body’s resistance increases significantly: a person copes with a shock state (if there was one, of course), his resistance to various diseases, allergic reactions, and working capacity increase.But such a state cannot last long, and if the stressful state continues for a sufficiently long time, then the same hormones lead to disruption of the activity of all body systems, up to death.

Hormones are specific, physiologically active substances produced by the endocrine glands.

Properties of hormones:

1. Hormones have high biological activity.

2. The size of the hormone molecules is relatively small.This ensures their penetration through the walls of the capillaries from the bloodstream into the tissues. In addition, the small size of the molecules allows hormones to exit the cells through the cell membranes.

3. Hormones are relatively quickly destroyed by tissues, therefore, to ensure a long-term effect, their constant release into the blood is necessary.

4. Hormones have relative specificity, which is of great practical importance.

5. Hormones influence metabolic processes through enzymatic systems.

Statement of a problematic question .

Consider a few facts.

1. A person can live without a stomach and gallbladder, with one lung, with one kidney, with half a liver, but he will die if a small gland is removed – the pituitary gland, which weighs 0.5 g. There are about ten endocrine glands in total. their mass is about 100 g.

2. ZhVS produces special substances – hormones (from the Latin word “harmao” – I excite) in negligible amounts; for example, a person needs 0.00003 g of vitamin B per day, and the hormone adrenaline is 1000 times less (15 g would be enough for all people in the world).

3. Hormones are very active, they strongly change the growth and development of the body, regulate metabolism; lack or excess of hormones cause painful changes in the weight and proportion of body parts (there are cases when the weight of some people reached 500-600 kg).

Why are IVS (endocrine glands) called small organs of great importance? What is their function in the body? (we discuss our opinion collectively).

Consider the fact: runners before the performance, as well as animals in danger, increase the adrenaline content in the blood.

Explain:

How organ functions and physiological processes change as a result;

What is the significance for the organism of these changes in a situation of tension (stress). Biologically active substances, enzymes, vitamins, hormones have a strong effect on the vital activity and health of the body. Compare these substances and explain the differences between them.

Questions for students to consolidate the studied material :

What role do WBCs play in the human body? What is their difference from the external secretion glands?

What are hormones? What is their mechanism of action?

What is the humoral regulation of the body?

What is the function of the thyroid gland in the body?

What is the importance of the adrenal glands?

What are the differences between nervous and humoral regulation?

What is the role of the pituitary gland?

OKVGU

For 109 years of its existence, the educational institution has made a significant contribution to the training of teaching staff.During its existence, it has trained more than 12,000 teachers. Among the graduates of the college there are many famous honored people, statesmen. This is the famous Soviet military leader, twice Hero of the Soviet Union I.I. Yakubovsky; Doctor of Sciences T.A. Galinkevich, A. Ya. Utenkov, V.V. Poznyakov; composer Ya.A. Kosolapov; writers I.V. Vasilevsky, A.S. Rusetsky, I.M. Shevtsov. Orsha College of Voronezh State University named after P.M. Masherov was awarded: in 1971 with the Certificate of Honor of the Supreme Soviet of the BSSR, in 1978 and 1983 with the Transitional Red Banner of the Ministry of Education of the USSR and the Central Committee of the Trade Union of Education Workers, Higher Education and Scientific Institutions.Currently Orsha College of Voronezh State University named after P.M. Masherova trains: primary school teachers, English teachers, physical education teachers, educators, programmers. For high-quality training of specialists, an appropriate material base has been created: 27 classrooms and laboratories, 2 reading rooms, 1 gym, 1 gym, 2 language laboratories, 3 computer classes. The book fund of the library has more than 80 thousand copies of educational, methodological, popular science and fiction.For nonresident students, there is a modern dormitory for 450 places, on the basis of which a social and cultural complex operates: a college history museum, a reading room, an assembly and a choreographic hall, music rooms for individual lessons, a studio of arts and crafts and fine arts, a gym. The teaching staff consists of 50 teachers, 13 of whom are masters; 75% have the highest and first qualification category. College teachers are actively involved in the processes of reforming education, research activities.Repeatedly took and are taking part in republican and international scientific and practical conferences and seminars, are the authors of many publications in the republican press. A.A.Zulev Director of Orsha College Educational Institutions Vitebsk State University named after P.M. Masherov

Monthly newspaper of Orsha College of Voronezh State University named after P.M. Masherov

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Orsha College of Voronezh State University named after P.M.M Masherov is listed on the Honor Board of the Orsha District

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In June 2010. the quality management system of the STB ISO 9001-2009 standard is certified

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Rol ‘gormona rosta v funktsionirovanii reproduktivnoy sistemy cheloveka | Mel’nichenko

The hormones that control human reproductive function include not only LH and FSH, but also the family of peptide hormones, including: growth hormone (GH), prolactin (PRL) and chorionic (placental) lactogen.The effect of GH on the body is multifaceted; the reproductive system is no exception. Over the past 20 years, an intensive study of the effect of PRL on the reproductive, immune, and nervous systems has been carried out, the result of which has been the discovery of a clear connection between the interaction of these three systems. The end of the 90s was marked by the beginning of the study of the effects of GH on the human body. The emerging data on the effect of GH deficiency on aging processes, restoration of fertility in both women and men create the prerequisites for the joint study of the effects of GH by endocrinologists, gynecologists, immunologists and neurophysiologists. …

The hormones that control human reproductive function include not only LH and FSH, but also a family of peptide hormones, including: growth hormone (GH), prolactin (PRL), and chorionic (placental) lactogen. Over the past 20 years, the influence of BPD on the functioning of the reproductive system has been thoroughly studied. Currently, there is an intensive study of the influence of GR on this system, since the lack of GR, as well as its excess, lead to disruptions in the activity of this system.The most striking manifestations of impaired GH secretion include acromegaly. Acromegaly is a severe neuroendocrine disease caused by chronic hyperproduction of GH somatotrophomy and the anterior pituitary gland, which occurs mainly at the age of 30-50 years, characterized by excessive growth of bones and soft tissues and the development of a number of severe somatic disorders. It should be noted that the appearance of vivid clinical symptoms, in which the diagnosis of acromegaly is not difficult for an internist, is preceded by many years, during which patients present nonspecific complaints of weakness, fatigue, headaches, excessive sweating, reproductive disorders, while men can complain of a slight decrease in libido, impotence, and the most frequent symptoms of the onset of acromegaly in women can be galactorrhea, menstrual irregularities, infertility, polycystic ovary disease, hirsutism, uterine fibroids; it is well known that acromegaly often manifests itself during pregnancy.Severe somatic and neurological disorders, which are caused by long-term hyperproduction of GH, significantly reduce the life expectancy of patients. The need for early diagnosis of acromegaly and its effective treatment is due not only to the obvious problems associated with the development of severe clinical and laboratory disorders, but also to the emergence of real and effective treatment methods, such as transsphenoidal adenomectomy, proton therapy, and the recently emerging possibility of conservative treatment with synthetic somatostatin drugs.Etiological features of the development of acromegaly In 95% of cases, an increase in the level of GH is due to the presence of a pituitary tumor – somatotropinoma. Acromegaly can develop as an isolated disease and be a part of type I multiple endocrine neoplasia syndrome (MEN-I) and McCune-Albright syndrome. Extrahypophyseal localization of the tumor is rather rare. There are isolated descriptions of the development of malignant tumors – somatocarcinomas, although invasive growth of somatotropin is quite frequent.An analogy can be drawn with prolactinomas. In the entire history of the study of prolactin-secreting pituitary tumors, only 13 cases of malignant neoplasms have been described, which were accompanied by the identification of distant metastases. There are a lot of cases of invasive prolactinomas. It is necessary to pay attention to the definitive differences between the concepts of “malignancy” and “invasiveness”. A pituitary tumor is malignant when distant metastases to organs and tissues are found.The very fact of invasion is not a sign of a malignant tumor of the pituitary gland. Ectopic somatrotropinomas are extremely rarely diagnosed. Typically, this type of tumor is found in the islet cells of the pancreas. Less than 1% of tumors are associated with increased secretion of growth hormone (STHRH) by the hypothalamus. Ectopic tumors producing STHRH from islet cells of the pancreas, bronchi, gastrointestinal tract, and lungs account for 2%. The main role in the pathogenesis of clinical manifestations of acromegaly is played by an increase in the level of GH, combined with the development of hypothalamic-pituitary insufficiency, which can be associated either with mechanical compression of the pituitary gland by the tumor tissue, or, which is much more common, intraoperative damage to the pituitary gland when performing adenomectomy with a transfrontal approach.As a rule, this leads to the development of secondary adrenal insufficiency with a decrease in the production of adrenocorticotropic hormone (ACTH). When thyro- and gonadotrophs are damaged, secondary hypothyroidism and hypogonadism develop, respectively. In addition, the clinical picture of acromegaly includes neurological disorders. What is GH, what are the mechanisms of its regulation, the effect on the body? GR is secreted by somatotrophs, which constitute about 50% of all cells of the adenohypophysis. The effects of GH are mediated by insulin-like growth factors (somatomedins), most of which are produced in the liver.The main growth factor mediating GH is insulin-like growth factor I (IGF-1). The secretion of GH is under complex physiological control, carried out both by the hypothalamus, through (STHRH) and somatostatin (SS), and by other hormones. Sex steroids stimulate the production of GH. This explains the increase in GH levels during pregnancy. In women with polycystic ovary disease, as well as in patients receiving estrogen therapy, the level of GH is increased. Glucocorticoids, on the other hand, inhibit the synthesis of GH.The effect of GH on the body is very diverse. By positively affecting the size of bone and muscle tissue, GH exhibits the effects of an anabolic hormone through IGF-1. The results of recent studies, which recorded a high content of IGF-1 in the corpus luteum and endometrium, are beginning to be used in practice when carrying out the fertilization of women with gonadotropic hypogonadism in vivo, when genetically engineered GH therapy is added to the treatment with gonadotropins, which leads to a dose-dependent increase in the activity of gonadotropins and the onset of pregnancy [1].It is necessary to note the lipolytic effect of GH, which results in a decrease in the volume of fat mass. Through IGF-1 and IGF-2, growth hormone has anabolic effects on cell growth and differentiation, chondrogenesis, linear growth. It is necessary to note the participation of thyroid hormones: thyroxine (T4) and triiodothyronine (T3) in the implementation of influences on the osteochondral apparatus [2]. Being a counterinsular hormone, GH increases the level of glycemia, stimulates gluconeogenesis and glycogenolysis; cortisol is involved in the implementation of these influences.The effects of GH on organs and tissues are schematically summarized below. Biological effects of GH Inhibition of GH production occurs with an increase in the level of IGF-1, which, along a long loop, stimulates the production of SS or inhibits the secretion of STHRH. GH secretion is influenced by factors such as stress, sleep, physical activity. Dopamine (DA), acting on b-adrenergic receptors, stimulates the production of CC, which leads to the suppression of GH secretion. When DA interacts with a2-adrenergic receptors, an increase in the synthesis of STHRH occurs, leading to an increase in the production of GH by the adenohypophysis.Knowledge of the specificity of the effects of DA on GH is mandatory in cases of a combination of acromegaly and hyperprolactinemic hypogonadism (HH), caused by the presence of pituitary prolactinoma, or in the differentiation of these nosoforms by prescribing drug therapy. In a healthy person, influences on a2-receptors that contribute to an increase in the level of GH prevail, in acromegaly, on the contrary, in some patients, dopaminomimetics, in particular bromocriptine, inhibit the secretion of GH. In cases of hyperprolactinemia, which can be caused by idiopathic hyperprolactinemia or prolactinoma, the administration of dopaminomimetics can lead to stimulation of the production of STHRH and, accordingly, GH.At the initial stages, acromegaly can be mistaken for HH and vice versa, while dopaminomimetics can be prescribed for both diseases, which will further complicate the interpretation of the data obtained in the study of GH. Therefore, it is necessary to conduct a thorough examination of patients with a diagnosis of hyperprolactinemic hypogonadism, which would include the study of PRL, GH, thyroid stimulating hormone (TSH). The latter study is necessary to exclude hypothyroidism, which is accompanied by an increase in the level of TSH and thyroliberin (TRH), the latter being prolactoliberin.Among the regulators of GH secretion is acetylcholine, which mediates its effects through a2-adrenergic receptors. The result of the described processes is the maintenance of the normal rhythm of GH secretion with a peak in the early morning hours and a relatively low concentration during the rest of the day. I would like to warn practitioners against a mechanistic approach to researching one or another hormone, since “bare” numbers, not supported by information about the treatment being carried out, the existing somatic and psychosomatic diseases, the patient’s psychological state, his eating habits, can lead to an incorrect diagnosis and, as a consequence, inadequate treatment.Clinical appearance of acromegaly The main clinical manifestations of acromegaly are summarized and represented by the following symptoms and physical signs. Symptoms Excessive sweating (50-52%). Headaches (37-44%). Carpal tunnel syndrome (25-51%). Osteoarthritis of various localization (18-41%). Visual disturbances (3%). Sleep apnea syndrome (8%). An increase in the size of the hands and feet. Impotence (36%). Hirsutism (24%). Amenorrhea (44%). Physical signs of acromegaly Prognathism. Diastemas.Macroglossia. Large hands with “cigar-shaped” fingers. Arterial hypertension. Bitemporal hemianopsia. Pathological changes on the part of III, IV, VI pairs of cranial nerves. As you can see, the clinical manifestations of acromegaly often mimic endocrine and gynecological diseases. The endocrine manifestations of acromegaly include hyperprolactinemia, which is found in more than 40% of cases and is caused either by the mixed nature of the tumor – somatoprolactinoma, or by hyperplasia of prolactotrophs due to compression of the pituitary pedicle by somatoropinoma, or by the prolact-like effects of GH.Amenorrhea and impotence occur in 50 – 75% of cases. In connection with the overproduction of IGF-1, cases of goiter and uterine fibroids are frequent. It should be noted that the size of the organs sometimes reaches such gigantic proportions, which greatly complicates the implementation of surgical interventions. Of the neurological disorders, it is necessary to note the appearance of parasthesias; tunnel syndrome, which develops as a result of infringement of n. medianus with hypertrophied cartilaginous tissues, chiasmal syndrome, intense headaches.For many years, the damage to physical health caused by acromegaly has been underestimated. At the same time, with acromegaly, such serious disorders develop as: arterial hypertension; hypertrophy of the ventricles and interventricular septum; cardiomegaly; myocardial dystrophy. In addition, patients with acromegaly are 3 times more likely than the general population to die from severe respiratory distress. With what it can be connected? Under the influence of IGF-1, pronounced hypertrophy of the upper and lower airways (cartilage, muscle and mucous structures) occurs, which results in obstruction of the airways and sharply increases the risk of developing sleep apnea.The existing changes force to classify patients as a group of high anesthetic risk, which must be taken into account when carrying out surgical interventions, in particular for uterine fibroids. Metabolic changes are accompanied by the development of insulin resistance, which can be expressed as impaired glucose tolerance and diabetes mellitus. Hypercalcemia associated with an increase in the formation of active metabolites of vitamin D3, namely 1,25-dihydrocholecalciferol (1,25 – (OH) 2D3), is diagnosed, hypertriglyceridemia and osteoporosis develop due to a decrease in estrogen secretion.Diagnosis of acromegaly The main laboratory markers used to assess the state of the somatotropic function of the pituitary gland are: study of the basal level of serum GH and the concentration of IGF-1. With an increase in the values ​​of both indicators, the presence of symptoms of the disease and the detection of a pituitary adenoma during magnetic resonance imaging of the head, the diagnosis is beyond doubt. It is much more difficult to differentiate between conditions accompanied by a slight increase in the level of GH.It is worth recalling that GH is a stress hormone, its concentration in the blood can increase in connection with the simplest medical procedures, for example, venipuncture. Simple functional tests have been developed, the conduct of which in doubtful cases will allow avoiding diagnostic errors and choosing the right treatment tactics. These tests include: Oral glucose tolerance test. Initially, the basal GH level is determined, after which the patient is given a solution of 75 g of glucose dissolved in 200 ml of water, and blood samples are taken with an interval of 30 minutes for 2.5 – 3 hours.Normally, being a counterinsular hormone, the level of GH decreases in response to glucose load. In the case of acromegaly, not only does the concentration of GH not decrease, but on the contrary, there is a paradoxical increase in the content of GH in the blood serum. Thyroliberin test. The first portion of blood is taken from the patient 30 minutes before the administration of thyroliberin. 500 μg of thyroliberin is injected intravenously, after which blood sampling is carried out at 15, 30, 60 and 120 minutes of the sample. In the absence of increased GH secretion, there is no response to the administration of thyroliberin.In acromegaly, there is a paradoxical increase in the level of GH during the entire study period. This test is also performed when the doctor suspects the presence of somatoprolactinoma, which is quite common. In this case, the paradoxical release of GR will confirm the mixed nature of the tumor, and the basal prolactin level will be increased, but at the 15-30th minute of the study, its further increase will not occur. Estimation of the average daily rhythm of GH secretion. Samples are taken every 30 – 60 minutes during the day.Normally, in 75% of samples, the GH level is at the lower limit of the norm, and in 25% of samples (midnight, early morning hours), a slight increase in GH values ​​is possible, which, however, do not exceed 10 ng / ml. The average daily concentration of GH in the blood serum of a healthy person is about 4.9 – 5.0 ng / ml. In the presence of acromegaly, the concentration of GH is increased throughout the day and can reach 500 ng / ml and higher. Determination of IGF-1 level. This indicator is the most reliable criterion for the diagnosis of disorders in the synthesis of GH, which is associated with a number of reasons.First, IGF-1 circulates in the blood not in a free state, but in a complex with a large molecule – a carrier, which is a protein with a molecular weight of 140.The half-life of this complex is from 3 to 18 hours, the half-life of GH does not exceed 20-30 min, and therefore the determination of the IGF-1 concentration will be more accurate. Secondly, the concentration of IGF-1 remains relatively constant throughout the day, in contrast to the pulsed fluctuation of GR. Third, IGF-1 does not exhibit the properties of a stress hormone, such as GH, ACTH, or prolactin (PRL).Normally, the IGF-1 concentration ranges from 0.4 to 2.0 U / L. It should be noted that the most complete diagnostic sense is the determination of GH and IGF-1 in blood serum. After adenomectomy, irradiation of the pituitary gland or treatment with synthetic SS preparations for acromegaly, a study of the level of GH and IGF-1 will serve to assess the effectiveness of the treatment. In addition to tests and diagnostic measures aimed at assessing the state of the patient’s somatotropic function, it is necessary to assess the state of vision and conduct perimetry.With narrowing of the visual fields and even more the development of bitemporal hemianopsia, which indicates compression of the optic nerve chiasm by the tumor tissue, an emergency adenomectomy is performed with a transfrontal approach. Among the instrumental examination methods, it is necessary to conduct an X-ray of the skull in 2 projections in order to visualize the pituitary gland, assess the size of the sella turcica, the state of the back, the bottom and surrounding tissues. Magnetic resonance imaging of the head (MRI) is the most informative for accurate visualization of a tumor formation, clarification of its size, nature of growth, relationship with the surrounding pituitary tissue.After carrying out all the diagnostic measures and making the diagnosis, it is necessary to solve one, the most difficult question: which method of treatment is most preferable in this case? Today, medicine has the following three well-proven treatment options for acromegaly: Adenomectomy. Radiation therapy (gamma or proton therapy) to the pituitary gland. Treatment with synthetic CC drugs (octreotide, sandostatin). Currently, adenomectomy can be carried out: transsphenoidal; transethmoid; transfrontally (transcranially).The choice of this or that approach depends on the following factors: Tumor size, there is a clear gradation of adenomas according to their size: microadenomas – tumor diameter less than 10 mm; macroadenomas – tumor diameter over 10 mm; giant adenomas – tumor diameter over 20 mm. The nature of tumor growth: infrasellar; suprasellar; parasellar. The presence of a microadenoma in a patient allows him to carry out a transsphenoidal adenomectomy. When macroadenomas are detected, transcranial adenomectomy is justified, some authors are of the opinion that, despite the size of the adenoma, with its infrasellar location, transsphenoidal adenomectomy is possible.The initiation of octreotide therapy can lead to a decrease in the size of the tumor, which will allow subsequently performing transsphenoidal adenomectomy. The same tactic is followed for giant adenomas. Radiation therapy, like the two treatments described above, has its place in the treatment of acromegaly. It can be used after surgery and a persistent increase in serum GH levels above 5 ng / ml, if it is impossible to perform an operation, which is associated with a high anesthetic risk of surgery and the inaccessibility of octreotide, as well as in the case of impossibility of radical removal of giant adenomas.The invasion of tumor tissue into the cavernous sinuses is an indication for radiation therapy. In recent years, the possibility of effective therapy with octreotide, the drug of choice for acromegaly, has emerged. As a synthetic somatostatin, octreotide inhibits the synthesis of GR by the anterior pituitary gland, thereby being an etiological factor affecting somatotrophs. In some patients, octreotide causes not only a decrease in the level of GH, but also a decrease in the size of the tumor. After completing this or that manual for acromegaly, it is necessary to evaluate the effectiveness of the intervention performed.For this purpose, investigate the level of GH and IGF-1 in the blood serum. The timing of control depends on the chosen method of treatment. After surgical removal of pituitary somatotropinomas, the concentration of GH and IGF-1 is examined in the early postoperative period every 3 to 6 months in the first year after the operation and once a year for 6 years after the operation. MRI control is performed 8-12 months after adenomectomy. If the chosen method of treatment was radiation therapy, then the first dynamic study of IGF-1 and GH is performed no earlier than 6 months later.Returning to the question of the treatment of acromegaly with dopamine agonists, the following should be noted: only in 20% of cases in patients with acromegaly there is a decrease in the GH level below 10 ng / ml, this suggests that in the remaining 80% of cases it may not only be ineffective, but vice versa, stimulating the production of STHRH, it will aggravate the course of acromegaly according to the mechanism described in detail above. In this regard, the following can be recommended: dopaminomimetics should not be used as first-line drugs in the treatment of acromegaly.They can be connected to treatment after surgery or radiation. Unfortunately, it must be admitted that, despite the complex treatment of acromegaly, in 30% of patients, the state of remission cannot be achieved. In this situation, treatment with dopamine agonists or sandostatin is warranted. Doctors monitoring patients treated for acromegaly should be aware of the development of a deficiency of one or more tropic hormones, and sometimes panhypopituitarism. Most often, secondary adrenal insufficiency and secondary hypothyroidism develop, so it is necessary to control the level of pituitary hormones in the early postoperative period, especially after transfrontal adenomectomy and 1-1.5 months after surgery.If acromegaly is diagnosed in young women, then after treatment, the question arises about the possibility and safety of pregnancy and childbirth. The world literature describes cases of a favorable course of pregnancy and timely delivery in women in remission, as well as those who received octreotide before pregnancy. Of course, this problem requires a more detailed joint discussion by gynecologists and endocrinologists. An increase in the concentration of GH leads to the development of severe somatic disorders that are difficult to treat, however, when carrying out certain measures, doctors manage to compensate for acromegaly, while the level of GH is either not determined at all, or does not exceed 1.5 – 2.0 ng / ml in morning hours.GH deficiency Several years ago, the problem of GH deficiency in adults was not reflected in the studies of endocrinologists, although questions related to insufficient secretory function of the pituitary gland have arisen since the time when patients with Sheehan’s syndrome were first described. This pathology is caused by the development of heart attacks or hemorrhages in the early postpartum period and is characterized by hypopituitarism. For many years, these patients received replacement therapy with glucocorticoids, thyroid hormones, sex steroids, however, despite this, the patients continued to present nonspecific complaints of increased fatigue, weakness, and psychosomatic complaints often appeared.In the study of hormones in the blood serum, no pathological abnormalities were found, and a decrease in the level of GH was not given importance. It turned out that with a decrease in GH secretion in the body of an adult, a number of disorders develop that are not as noticeable as manifestations of GH hypersecretion, but are no less significant for the body. Table Tables 1 and 2 summarize the disorders that develop with GH deficiency. Table 1. Metabolic disorders in GH deficiency Metabolism Disorders Fat and carbohydrate Increase in total and visceral adipose tissue Decrease in lipolysis activity Increase in triglycerides, cholesterol, LDL Impaired glucose tolerance Protein Decrease in muscle mass Decrease in protein synthesis activity, negative nitrogen balance Calcium Decrease in bone mass , negative calcium balance Table 2.Disorders in organs and tissues with GH deficiency Organs and tissues Disorders Skeletal muscles and myocardium Decreased heart rate Decreased VO2 max Decreased left ventricular wall thickness and decreased cardiac output Immune system Decreased in vitro function of T and B lymphocytes Decreased functional activity of macrophages Decreased humoral response to vaccination Skin Decreased thickness of the epidermis and dermis Deterioration of wound healing Note. Violations should also include changes in the quality of life of patients, expressed in worsening sleep, well-being, and decreased mood.As a commentary on the above schemes, it should be noted that all or almost all of the described problems develop in elderly people who do not suffer from any disorders of the endocrine system [3]. Thus, patients with Sheen’s syndrome, pituitary dwarfism, patients treated for pituitary growth hormone, and the elderly need GH replacement therapy. In case of suspicion of the presence of GH deficiency in a patient, a number of the following laboratory tests will confirm or deny this diagnosis.Insulin test. Intravenous insulin is administered at the rate of 0.2 U per 1 kg of body weight. Blood samples are taken again after 15, 30, 60, 90 minutes. The sample is considered positive in the absence of an increase in GH. Study of the circadian rhythm of GH secretion with elucidation of the effect of sleep on GH secretion. The sample is positive, i.e. there is a deficiency of GH, in the absence of an increase in the concentration of the hormone in the early morning hours. Test with L-DOPA. Initially, the level of GH is determined, the patient takes 0.5 g of L-DOPA orally, which normally should lead to stimulation of somatotrophs and an increase in GH secretion.Exercise test. Against the background of physical activity in a person with preserved somatotroph function, the level of GH increases. If in 2 of the performed samples the increase in GH is less than the normative indicators, the diagnosis of “GH deficiency” will be confirmed, which will require replacement therapy with genetically engineered GH. For the first time in adult practice, it began to be used in patients with pituitary dwarfism after they reached puberty. Against the background of substitution therapy, the patients showed an increase in muscle mass, bone tissue, normalization of carbohydrate and lipid metabolism, and an improvement in well-being.Genetically engineered GR was used in men with asthenospermia. Six infertile couples were investigated, the cause of infertility was asthenospermia, 3 men were treated with artificial GH, others were injected with placebo. On the background of treatment in men receiving GH therapy, fertility was restored, which was accompanied by the onset of pregnancy in 3 couples. In the placebo control group, asthenospermia persisted. So, the influence of GH on the body is multifaceted, the reproductive system is no exception.Over the past 20 years, an intensive study of the effect of PRL on the reproductive, immune, and nervous systems has been carried out, the result of which has been the discovery of a clear connection between the interaction of these three systems. The end of the 90s was marked by the beginning of the study of the effects of GH on the human body. The emerging data on the effect of GH deficiency on the aging process and the restoration of fertility in both women and men create the prerequisites for a joint study of the effects of GH by endocrinologists, gynecologists, immunologists, and neurophysiologists.

1. Nabarro, J. D. N. (1987), Acromegaly. Clinical endocrinology, Christie Hospital.
2. Alexannder, L., Appleton, D., Hall, R. Epidemiology of acromegaly // Cl. Endocrinology – 1980 – vol. 12 P. 71 -79.
3. Togod A. A., O Neill P. A., Shalet S. M. Beyond the somatopause: GH deficiensy in adults over the age of 60 years // J. clinical Endocrinology Metab.- 1996 – vol. 81 – P. 460 – 465.

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Answer Endocrine system – Workbook on biology Grade 8 Kolesov D.V., Mash R.D., Belyaev I.N.

251. Formulate a few questions, answers to …

1) What glands belong to the glands of internal, mixed and external secretion?

2) What is the function of hormones?

3) How is the nervous and humoral regulation carried out?

4) What properties do hormones have?

252. Read § 58 “The role of endocrine regulation” …

• Answer:

253. Answer on what basis …

254. Indicate the value and general properties of hormones.

• Answer:

  Meaning: they regulate the activity of organs and cells

  Properties:

  1) they operate in negligible amounts

  2) After their action, hormones are destroyed

255. Combine the listed structures with arrows indicating …

• Answer:

256. Read § 59 “Functions of the endocrine glands”.

• Answer:

  Name	Functions
  Pituitary gland	Normal growth of both the whole organism as a whole and its individual parts
  Thyroid gland	Metabolism, development of the body
  Adrenal glands	Growth and development of the body, enhanced protein synthesis, the body’s response to danger
  Sex glands	Provide the reproductive function of the body
  Pancreas	Digestion, absorption of glucose and maintenance of its constant level
  Thymus	Protective function of the body

257. Fill in the table.

• Answer:

  Disease	Reasons	Symptoms
  Cretinism	Lack of thyroid hormones	Delayed physical and mental development
  Dwarfism	Lack of pituitary growth hormone	Low rise
  Gigantism	Excess growth hormone	Very tall
  Basedow’s disease	Excess thyroid hormones	Increased body temperature, thinness, increased excitability, bulging eyes
  Myxedema	With a lack of thyroid hormone	Weakness, drowsiness, edema, lethargy
  Acromegaly	Excess growth hormone at an older age	Increase in body part
  Diabetes mellitus	Lack of insulin	Weakness, low immunity, allergy

258. Find errors in the text given …

1. The glandular endocrine ducts have ducts through which the secret enters the blood.

2. The endocrine glands secrete biologically active regulatory substances – hormones.

3. After exposure to target organs, the hormone is destroyed.

4. Potassium is required for the successful formation of thyroid hormone.

5. If the thyroid gland secretes too much hormone in an adult, Graves’ disease develops.

6. For people with Graves’ disease, overweight is characteristic, because they slow down the processes of biological oxidation.

• Answer:

  4) Not potassium, but iodine

  5) Basedow’s disease occurs when the thyroid gland is overactive.

  6) On the contrary, thinness is characteristic of people with this disease, because biological oxidation processes are accelerated.

259.