What structures produce hormones: Illustrations of Anatomy, Function, Glands $ Organs
18.1 Types of Hormones – Concepts of Biology – 1st Canadian Edition
An endocrinologist is a medical doctor who specializes in treating disorders of the endocrine glands, hormone systems, and glucose and lipid metabolic pathways. An endocrine surgeon specializes in the surgical treatment of endocrine diseases and glands. Some of the diseases that are managed by endocrinologists: disorders of the pancreas (diabetes mellitus), disorders of the pituitary (gigantism, acromegaly, and pituitary dwarfism), disorders of the thyroid gland (goiter and Graves’ disease), and disorders of the adrenal glands (Cushing’s disease and Addison’s disease).
Endocrinologists are required to assess patients and diagnose endocrine disorders through extensive use of laboratory tests. Many endocrine diseases are diagnosed using tests that stimulate or suppress endocrine organ functioning. Blood samples are then drawn to determine the effect of stimulating or suppressing an endocrine organ on the production of hormones. For example, to diagnose diabetes mellitus, patients are required to fast for 12 to 24 hours. They are then given a sugary drink, which stimulates the pancreas to produce insulin to decrease blood glucose levels. A blood sample is taken one to two hours after the sugar drink is consumed. If the pancreas is functioning properly, the blood glucose level will be within a normal range. Another example is the A1C test, which can be performed during blood screening. The A1C test measures average blood glucose levels over the past two to three months by examining how well the blood glucose is being managed over a long time.
Once a disease has been diagnosed, endocrinologists can prescribe lifestyle changes and/or medications to treat the disease. Some cases of diabetes mellitus can be managed by exercise, weight loss, and a healthy diet; in other cases, medications may be required to enhance insulin release. If the disease cannot be controlled by these means, the endocrinologist may prescribe insulin injections.
In addition to clinical practice, endocrinologists may also be involved in primary research and development activities. For example, ongoing islet transplant research is investigating how healthy pancreas islet cells may be transplanted into diabetic patients. Successful islet transplants may allow patients to stop taking insulin injections.
You and Your Hormones from the Society for Endocrinology
Where is my hypothalamus?
Computer artwork of a person’s head showing the left side of the brain with the hypothalamus highlighted.
The hypothalamus is located on the undersurface of the brain. It lies just below the thalamus and above the pituitary gland, to which it is attached by a stalk. It is an extremely complex part of the brain containing many regions with highly specialised functions. In humans, the hypothalamus is approximately the size of a pea and accounts for less than 1% of the weight of the brain.
What does my hypothalamus do?
One of the major functions of the hypothalamus is to maintain homeostasis, i.e. to keep the human body in a stable, constant condition.
The hypothalamus responds to a variety of signals from the internal and external environment including body temperature, hunger, feelings of being full up after eating, blood pressure and levels of hormones in the circulation. It also responds to stress and controls our daily bodily rhythms such as the night-time secretion of melatonin from the pineal gland and the changes in cortisol (the stress hormone) and body temperature over a 24-hour period. The hypothalamus collects and combines this information and puts changes in place to correct any imbalances.
What hormones does my hypothalamus produce?
There are two sets of nerve cells in the hypothalamus that produce hormones. One set sends the hormones they produce down through the pituitary stalk to the posterior lobe of the pituitary gland where these hormones are released directly into the bloodstream. These hormones are anti-diuretic hormone and oxytocin. Anti-diuretic hormone causes water reabsorption at the kidneys and oxytocin stimulates contraction of the uterus in childbirth and is important in breastfeeding.
The other set of nerve cells produces stimulating and inhibiting hormones that reach the anterior lobe of the pituitary gland via a network of blood vessels that run down through the pituitary stalk. These regulate the production of hormones that control the gonads, thyroid gland’ data-content=’1456′ >thyroid gland and adrenal cortex, as well as the production of growth hormone, which regulates growth, and prolactin, which is essential for milk production. The hormones produced in the hypothalamus are corticotrophin-releasing hormone, dopamine, growth hormone-releasing hormone, somatostatin, gonadotrophin-releasing hormone and thyrotrophin-releasing hormone.
What could go wrong with my hypothalamus?
Hypothalamic function can be affected by head trauma, brain tumours, infection, surgery, radiation and significant weight loss. It can lead to disorders of energy balance and thermoregulation, disorganised body rhythms, (insomnia) and symptoms of pituitary deficiency due to loss of hypothalamic control. Pituitary deficiency (hypopituitarism) ultimately causes a deficiency of hormones produced by the gonads, adrenal cortex and thyroid gland, as well as loss of growth hormone.
Lack of anti-diuretic hormone production by the hypothalamus causes diabetes insipidus. In this condition the kidneys are unable to reabsorb water, which leads to excessive production of dilute urine and very large amounts of drinking.
Last reviewed: Feb 2018
Endocrine System : Hormone Glands
Endocrine System : Hormone Glands
- Ovary (Follicle And Corpus Luteum)
- Adrenal Glands (Medulla And Cortex)
- Parathyroid Gland
- Posterior Pituitary Gland
- Anterior Pituitary Gland
- Pineal Gland
(click on each gland title for detailed information and imaging from Encyclopaedia Brittanica)
Hormone Released: Estrogens
Hormone Structure: Steroid
Hormone Function: Develop & maintain
female sex organs & characteristics; Initiates building
of uterine lining
Hormone Regulator: Follicle-stimulating
Hormone Released: Progesterone & Estrogens
Hormone Structure: Steroid
Hormone Function: Influences breast development
and menstrual cycles; Promotes growth and differentiation
of uterine lining; Maintains pregnancy
Hormone Regulator: FSH & Luteinizing
Hormone Released: Androgens (mainly testosterone)
Hormone Structure: Steroid
Hormone Function: Develop & maintain male sex organs & characteristics;
aid sperm production
Hormone Regulator: FSH & LH
Hormone Released: Insulin
Hormone Structure: Polypeptide
Hormone Function: Lowers blood sugar; Increases glycogen storage in liver;
Stimulates protein synthesis
Hormone Regulator: Blood glucose concentrations
Hormone Released: Glucagon
Hormone Structure: Polypeptide
Hormone Function: Stimulates glycogen breakdown in liver; Increases blood
sugar (glucose) concentration
Hormone Regulator: Blood glucose & amino acid concentrations
Hormone Released: Somatostatin
Hormone Structure: Peptide
Hormone Function: Suppresses release of insulin & glucagon
Hormone Regulator: Nervous system,
feedback from growth hormone
Glands (Medulla And Cortex)
Hormone Released: Epinephrine (adrenaline)
Hormone Structure: Amino Acid Derivative (Catecholamine)
Hormone Function: Constricts blood vessels in skin, kidneys and gut which
increases blood supply to heart, brain and skeletal muscles
and leads to increased heart rate & blood pressure;
Stimulates smooth muscle contraction; Raises blood glucose
levels which increases available energy
Hormone Regulator: Sympathetic nervous
Hormone Released: Norepinephrine (noradrenaline)
Hormone Structure: Amino Acid Derivative (Catecholamine)
Hormone Function: Constricts blood vessels throughout the body; Increases
heart rate & contraction of cardiac muscles; Increases
Hormone Regulator: Sympathetic nervous
Hormone Released: Glucocorticoids (mainly cortisol &
Hormone Structure: Steroids
Hormone Function: Regulates blood glucose concentrations by affecting many
aspects of carbohydrate metabolism; Affects growth; Decreases
effects of stress and anti-inflammatories
Hormone Regulator: Corticotopin-
releasing hormone (CRH) from hypthalamus; Adrenocorticotropic
Hormone Released: Mineralocorticoids (mainly aldosterone)
Hormone Structure: Steroid
Hormone Function: Regulates sodium, water & potassium excretion by the
Hormone Regulator: Renin & Angiotensin
Hormone Released: Gonadocorticoids (mainly androgens (male
Hormone Structure: Steroid
Hormone Function: Contribute to secondary sex characteristics (particularly
after menopause in women)
Hormone Regulator: Adrenocorticotropic hormone (ACTH)
Hormone Released: Several Thymosin & Thymopoietin
hormones; Thymic humoral factor; Thymostimulin; Factor
Hormone Structure: Peptide
Hormone Function: Stimulates T cell development in thymus & maintainence
in other lymph tissue; Involved in some B cells developing
into antibody-producing plasma cells
Hormone Regulator: Not known
Hormone Released: Parathyroid hormone (PTH)
Hormone Structure: Peptide
Hormone Function: Increases blood calcium concentrations by stimulating
calcium release from bone, promoting calcium uptake
from intestinal tract and decreasing calcium excretion
by the kidney; Decreases blood phosphate level
Hormone Regulator: Calcium
concentrations in blood
Hormone Released: Thyroxine & Triiodothyronine
Hormone Structure: Amino Acid
Hormone Function: Develop
& maintain female sex organs & characteristics;
Initiates building of uterine lining
Hormone Regulator: Thyroid-stimulating
hormone (TSH),regulated by thyrotropin-releasing
hormone (TRH) from the brain
Hormone Released: Calcitonin
Hormone Structure: Peptide
Hormone Function: Inhibits calcium release from bone thus lowering
blood calcium levels
Hormone Regulator: Blood calcium
Posterior Pituitary Gland
Hormone Released: Antidiuretic hormone
Hormone Structure: Peptide
Hormone Function: Increases water absorption from kidney; Raises
Hormone Regulator: Blood osmolarity
Hormone Released: Oxytocin
Hormone Structure: Peptide
Hormone Function: Stimulates contraction of pregnant uterus &
release of breast milk after childbirth
Hormone Regulator: Nervous system
Anterior Pituitary Gland
Hormone Released: Growth hormone
Hormone Structure: Protein
Hormone Function: Stimulates bone & muscle growth; Promotes
protein synthesis & fat mobilization
Hormone Regulator: Hypothalamic hormones
Hormone Released: Prolactin
Hormone Structure: Protein
Hormone Function: Promotes production & secretion of milk
in humans after childbirth
Hormone Regulator: Hypothalamic hormones
Hormone Released: Thryoid-stimulating hormone
Hormone Structure: Glycoprotein
Hormone Function: Stimulates production & secretion of thyroid
Hormone Regulator: Blood thyroxine levels; Hypothalamic hormones
Hormone Released: Adrenocorticotropic hormone
Hormone Structure: Polypeptide
Hormone Function: Stimulates adrenal cortex to secrete cortisol
& other steroids
Hormone Regulator: Corticotropin-releasing
hormone (CRH) from the Hypothalamus; Blood cortisol
Hormone Released: Releasing & inhibiting
Hormone Structure: Peptides
Hormone Function: Responds to signals from the nervous system
&/or blood concentrations of circulating
hormones by releasing hormones that act on
the pituitary gland
Hormone Regulator: Blood & local levels of specific substances
Hormone Released: Melatonin
Hormone Structure: Amino Acid Derivative
Hormone Function: Involved in circadian rhythms: Antigonadotropic
effect. Exposure to light decreases release,
darkness increases release
Hormone Regulator: Exposure to light/dark cycles
- Campbell, N.A. 1990. Biology.
Second Edition. Redwood City, CA: Benjamin/Cummings
Publishing Company, Inc.
- Encyclopaedia Britannica Online
The Menstrual Cycle | Patient Education
The female reproductive system is a wonderfully complex system involving continuous communication between the brain centers and the ovary. Hormones secreted by the hypothalamus, the pituitary and the ovary are the messengers that regulate the monthly cycle.
The Hypothalamus and the Pituitary
The hypothalamus is located centrally in the brain and communicates by way of an exchange of blood with the pituitary gland. Several neuroendocrine agents, or hormones, are produced by the hypothalamus. The most important hormone for reproduction is called gonadotropin releasing hormone, better known as GnRH. It is released in a rhythmic fashion every 60 to 120 minutes.
GnRH stimulates the pituitary gland to produce follicle stimulating hormone (FSH), the hormone responsible for starting follicle (egg) development and causing the level of estrogen, the primary female hormone, to rise. Leutinizing hormone (LH), the other reproductive pituitary hormone, aids in egg maturation and provides the hormonal trigger to cause ovulation and the release of eggs from the ovary.
The main function of the ovaries is the production of eggs and hormones. At birth, the ovaries contain several million immature eggs. No new eggs will be developed. These eggs are constantly undergoing a process of development and loss. Most will die without reaching maturity. This process of egg loss occurs at all times, including before birth, before puberty and while on birth control pills. The ovary undergoes a constant process of egg depletion throughout its lifetime.
As the levels of FSH and LH in the blood increase with puberty, the eggs begin to mature and a collection of fluid — the follicle — begins to develop around each one.
The first day of menses is identified as cycle day one. Estrogen is at a low point. Therefore, the pituitary secretes FSH and LH, a process which actually begins before the onset of your menses. These hormones in turn stimulate the growth of several ovarian follicles, each containing one egg. The number of follicles in the monthly “cohort” of developing follicles is unique to each individual. One follicle will soon begin to grow faster than others. This is called the dominant follicle.
As the follicle grows, blood levels of estrogen rise significantly by cycle day seven. This increase in estrogen begins to inhibit the secretion of FSH. The fall in FSH allows smaller follicles to die off. They are, in effect, “starved” of FSH.
When the level of estrogen is sufficiently high, it produces a sudden release of LH, usually around day thirteen of the cycle. This LH peak triggers a complex set of events within the follicles that result in the final maturation of the egg and follicular collapse with egg extrusion. Ovulation takes place 28 to 36 hours after the onset of the LH surge and 10 to 12 hours after LH reaches its peak.
The cells in the ovarian follicle that are left behind after ovulation undergo a transformation and become the corpus luteum. In addition to estrogen, they now produce high amounts of progesterone to prepare the lining of the uterus for implantation.
The Luteal Phase
The luteal phase, or second half of the menstrual cycle, begins with ovulation and lasts approximately 14 days — typically 12 to 15 days.
During this period, changes occur that will support the fertilized egg, which is called an embryo, should pregnancy result. The hormone responsible for these changes is progesterone, which is manufactured by the corpus luteum. Under the influence of progesterone, the uterus begins to create a highly vascularized bed for a fertilized egg.
If a pregnancy occurs, the corpus luteum produces progesterone until about 10 weeks gestation. Otherwise, if no embryo implants, the circulating levels of hormone decline with the degeneration of the corpus luteum and the shedding of the lining of the uterus (endometrium), leading to bleeding.
The lining of the uterus, or endometrium, prepares each month for the implantation of an embryo. This preparation occurs under the influence of estrogen and progesterone from the ovary. If no pregnancy develops, the endometrium is shed as a menstrual period, about fourteen days after ovulation.
Endocrine Structures and Functions – Anatomy & Physiology
Hormones are the chemical messengers of the endocrine system. They elicit specific responses by binding to receptors on or in target cells.
The time it takes the body to degrade 50 percent of a predetermined amount of hormone is called the hormone’s half-life. A hormone with a long half-life would persist in the blood long after the endocrine gland had stopped releasing it.
Many of these factors are a function of the type of hormone produced. Although there are many different hormones in the human body, they can be divided into three classes based on their chemical structure: lipid-derived hormones, amino acid-derived hormones, and peptide hormones.
The lipid-derived hormones include steroid hormones and eicosanoids. Steroid hormones, the primary class of lipid hormones in humans, are derived from cholesterol and show structural similarity to that molecule. Examples of steroid hormones include estrogen and testosterone, which are released by reproductive organs, and aldosterone and cortisol, which are released by the adrenal glands.
Steroid hormones are released as synthesized. They are insoluble in water, so to circulate through the blood they bind to transport proteins in serum. Since they are bound to carrier proteins, steroid hormones typically remain in circulation longer than other classes of hormones. Recall that the “lifetime” of a molecule from production to destruction is called the half-life. The steroid hormone cortisol has a half-life of 60 to 90 minutes, whereas epinephrine, an amino acid-derived hormone, has a half-life of approximately one minute. They are eventually degraded and excreted in urine or bile.
Eicosanoids are a class of signalling molecules derived from polyunsaturated fatty acids. They are typically released as paracrine signals upon stimulation and are only active for a few seconds.
Eicosanoids are a class of signalling molecules derived from polyunsaturated fatty acids. They are typically released as paracrine signals upon stimulation and are only active for a few seconds.
Of the amino acid-derived hormones, some circulate for only a few minutes while others may circulate for days. The amino acid tyrosine is the precursor for two groups of hormones: the thyroid hormones, produced in the thyroid gland; and the catecholamines (epinephrine and norepinephrine), produced in the adrenal medullae. The amino acid tryptophan is the precursor for the hormone melatonin, secreted by the pineal gland, and the hormone serotonin, which is quite widespread in the body. Some of these hormones have a circulating half-life of a few days (thyroid hormones) while some are rapidly degraded (catecholamines).
Peptide hormones are short peptides and polypeptide chains. Recall that peptides are usually made up of fewer than 50 amino acids and proteins are typically longer than that. Some peptide hormones of longer lengths can have secondary structures. Protein hormones, being much longer than peptides, can have more extensive three-dimensional structures and can even be globular.
Peptide hormones are a diverse group and include molecules that are only a few amino acids, such as antidiuretic hormone and oxytocin (each with 9 amino acids), produced by the pituitary gland. This class also includes proteins, such as growth hormone (191 amino acids), and glycoproteins, such as follicle-stimulating hormone (92 amino acids with glycosylation). Peptide hormones can either be released as produced or stored and released in response to stimulus. Most are water soluble and are easily transported in blood plasma, but some also bind to transport proteins. Most have a half life of minutes.
The structures of peptide hormones (a) oxytocin, (b) growth hormone, and (c) follicle-stimulating hormone. This image by OpenStax is licensed under a Creative Commons Attribution License 4.0. Access for free at https://openstax.org/books/biology-2e/pages/1-introduction
Control of Hormone Production
Hormone production can be regulated by positive and negative feedback pathways. In positive feedback systems, the release of a hormone leads to an action that stimulates release of more of the same hormone.
Oxytocin released by the pituitary gland prior to childbirth stimulates contraction of the uterus and increases pressure on the cervix. The increased pressure signals the pituitary to release even more oxytocin, which increases force of contractions, leading to even more cervical pressure. This amplification cycle continues until childbirth is complete. After the baby is born, the stretch receptors are no longer stimulated and the release of oxytocin decreases.
In a hormonal negative feedback loop, when a stimulus causes the release of a hormone (Hormone A), the hormone binds to the target cell receptor, causing the necessary metabolic change toward homeostasis. In a negative loop, the effect of this metabolic change is to counter the stimulus that caused the release of Hormone A. Once the cause of the stimulus returns to normal range, the production of that hormone stops and plasma level of that hormone returns to the normal (pre-stimulus) level. In this way, the concentration of most hormones in blood is maintained within a narrow range.
The hypothalamus monitors the plasma level of thyroid hormones, among others. When the level drops, the hypothalamus stimulates the anterior pituitary to release a hormone (Thyroid Stimulating Hormone, or Thyrotropin) that stimulates the thyroid to release thyroid hormones. Increased levels of the thyroid hormones in the blood then feed back to the hypothalamus and anterior pituitary to inhibit further stimulation of the thyroid gland. Other homeostatic imbalances, such as low body temperature, can also stimulate the hypothalamus to stimulate the anterior pituitary to release thyrotropin. Thyroid hormones play an important role in metabolic heat production via ATP production.
Stimuli Regulating Hormone Production
There are three mechanisms by which endocrine glands are stimulated to synthesize and release hormones: humoral regulation, hormonal regulation, and neural regulation.
The term humoral is derived from the term humor, which refers to bodily fluids such as blood and other extracellular fluids. Humoral stimuli regulate the release of hormones in response to specific changes in extracellular fluids, such as the concentration of a particular ion or solute in the blood or even the overall solute levels in the blood.
A rise in blood glucose level triggers the pancreatic release of insulin. Insulin causes blood glucose levels to drop, which signals the pancreas to decrease insulin production through a negative feedback loop. Similarly, low blood calcium stimulates the release of parathyroid hormone from the parathyroid gland which stimulates the release of calcium from bone, decreases calcium excretion in urine and promotes calcium absorption in the digestive system.
Tropic Hormonal Stimuli
With tropic hormonal stimuli, a hormone is produced and released by an endocrine gland in response to another hormone (known as “tropic hormones”). These hormones controlling release of another hormone are called tropic (meaning “turn toward,” pronounced “tro’-pick”; not same as geographical “trop-ic”).
The hypothalamus produces hormones that stimulate the anterior pituitary. The anterior pituitary in turn releases hormones that regulate hormone production by other endocrine glands. For example, the anterior pituitary releases thyroid-stimulating hormone, which stimulates the thyroid gland to produce the hormones T3 and T4. As blood concentrations of T3 and T4 rise, they inhibit further hormone production by both the pituitary and the hypothalamus in a negative feedback loop.
Note… Sometimes students get confused between tropic and trophic hormones. Tropic hormones stimulate release of other hormones from endocrine cells, such as those discussed here. Trophic (meaning “nourishment or nurse”) hormones stimulate non-endocrine cell growth and development, such as growth hormone, estrogen and testosterone.
The nervous system can also directly stimulate endocrine glands to release hormones through a mechanism known as neural stimuli.
Neuronal signaling from the sympathetic nervous system directly stimulates the adrenal medulla to release the hormones epinephrine and norepinephrine in response to stress.
Distance of Hormonal Signaling
Cells communicate with one another via chemical messengers. The communication may happen between cells close by or far away from the cells that produces the messenger (signal). For example, released hormones travel throughout the body and affect any cells with receptors for the specific hormones. Autocrine signaling (auto- means self) affects the cells that released the signaling molecule. Paracrine signaling (para- means alongside) affects local cells other than the secreting cells. While traditionally a hormone is thought to have its effect at a distance from where it is secreted, the definition of hormones now include paracrine and autocrine mechanisms as well. The all-inclusive term, Endocrine signaling, includes all types of communication where chemical molecules produced from a cell affect the metabolism of another cell (paracrine or endocrine) or that of its own (autocrine).
Hormones mediate changes in cells by binding to specific receptors; individual hormones have their own unique receptor or class of receptors. A cell that has a receptor for a specific hormone is called a target cell. A hormone can, therefore circulate throughout the body, contacting many different cell types, but affecting only those cells that possess the specific receptor. A receptor is a protein (cell membrane or intracellular) that binds specifically to a particular hormone. Receptors for a specific hormone may be found in or on many different target cells, or may be limited to a small number of specialized cells.
Thyroid hormones act on almost all cells of the body, stimulating metabolic activity throughout the body. However, thyroid stimulating hormone (TSH) acts only on the endocrine cells of the thyroid gland. Cells can have many receptors for the same hormone, but may also possess receptors for many different types of hormones. Follical stimulating hormone (FSH), which is produced by the anterior pituitary gland in the brain and circulates throughout the body, primarily impacts reproductive tissues in men and women, and these tissues also have receptors for thyroid hormones.
The number of receptors that respond to a hormone determine the cell’s potential sensitivity to that hormone and the resulting cellular response. The number of receptors that respond to a hormone can change, resulting in increased or decreased cell sensitivity. Since alcohol (ethanol) inhibits glutamate receptor channels, people with high alcohol levels show higher number of glutamate receptors in a classic example of up-regulation that makes the cells more sensitive to the hormone to try to maintain the normal level of response to glutamate (homeostasis). The number of cell surface receptors can also decrease in response to rising hormone levels, called down-regulation, leading to reduced cellular response to the hormone. Thus, the action of a hormone can be regulated either by the amount of hormone in circulation or by the number of receptors (either inside the cell or on the cell surface) available at that time for that hormone.
Hormones bind to receptors and cause changes in cellular function. Receptors can be found either inside the cell (intracellular receptors) or on the cell’s surface (plasma membrane receptors). Knowing the location of a specific receptor provides important information about the mechanism that specific hormone uses to affect cell physiology.
Intracellular Hormone Receptors
Steroid hormones are lipophilic and need transport proteins in the blood. Once released from their transport protein, the non-polar hormone is able to diffuse across the plasma membrane of cells. Recall that the lipid bilayer of the plasma membrane of cells uses amphiphilic phospholipids to compartmentalize the cytoplasm of a cell. When a steroid hormone crosses the plasma membrane of a target cell, it binds to an intracellular hormone receptor in the cytoplasm, on intracellular membrane system (ER) or, within the nucleus of the cell. The receptor/hormone complex can then bind to a specific site on DNA and act as a transcription regulator to increase or decrease the synthesis of particular mRNA molecules coded by these specific genes. This, in turn, alters mRNA production, which determines the amount of corresponding protein that is synthesized. The steroid hormone regulates specific cell processes. The rate of transcription and protein synthesis is directly proportional to the amount of hormone forming receptor/hormone complexes; so if the hormone production increases, so does the physiological effect in the body.
The thyroid hormones, T3 and T4, also use plasma transport proteins and intracellular DNA-binding receptors. There are, however, some important physiological differences with the steroid hormone mechanism. The target cells have membrane transport proteins that transport the thyroid hormones into the cell. The Thyroid hormone receptor is found bound to a transcription repressor protein on the DNA. The binding of the hormone with the receptor-repressor complex to form the receptor/hormone complex causes the repressor protein to dissociate, and a transcription activator protein becomes associated with the receptor. This, in turn, initiates transcription.
Binding of Lipid-Soluble Hormones. This image by OpenStax is licensed under a Creative Commons Attribution License 4.0. Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction
Plasma Membrane Hormone Receptors
Most peptide and amino acid hormones are polar and therefore cannot diffuse through the plasma membrane of cells. So, they bind to plasma membrane hormone receptors on the outer surface of the plasma membrane. Unlike steroid hormones, polar hormones also alter intracellular processes and can also affect the target cell’s transcription. Since they cannot enter the cell and act directly on any DNA-binding proteins, they exert their transcriptional effects through intermediate molecules called second messengers as described below. Catecholamines (amine class) and polar eicosanoids (lipid-derived class) also bind to cell-surface hormone receptors.
Binding of these hormones to a cell membrane surface receptor results in activation of a signaling pathway that triggers a cascade of intracellular activity and specific effects associated with the hormone. Most hormones that bind at the surface receptor remain outside the target cell. Some hormones are taken into the cell by endocytosis to initiate the intracellular biochemical response from within vesicles. The hormone that initiates the signaling pathway, the first messenger, activates a second messenger within the cell.
Binding of Water-Soluble (Polar) Hormones. This image by OpenStax is licensed under a Creative Commons Attribution License 4.0. Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction
Glucagon is produced when blood sugar drops. The glucagon binds to its receptor on target liver cells and stimulates two different metabolic reactions inside the cell. The liver cells will be stimulated to break down stored glycogen to glucose and to synthesize new glucose from some amino acids. As a result, glucose is released into the blood and blood sugar returns to normal.
G-proteins are a class of trans-membrane cell surface proteins that can be activated by hormones or ions and other chemicals for cell signaling. G-proteins remain inactive unless a hormone is bound to its cell surface receptor. Inactive G-proteins are bound to GDP on its cytoplasmic side. When a hormone binds to the cell surface receptor the bound GDP is replaced by GTP.
Activated G-proteins can have different functions depending on the hormone receptor: it can open a membrane protein channel; it can release a small molecule; or it can activate a membrane-bound enzyme. There is a large variety of G-protein-induced effects. For example, G-protein-linked ion channels can stimulate movements of ions across the membranes. There are specific channels for potassium, sodium, calcium or chloride.
For G-protein activated membrane-bound enzymes, there are large numbers of activated enzymes. One of the membrane bound enzymes that the G-Protein coupled receptor (GPCR) activates upon binding to a hormone molecule is the adenylate cyclase. This enzyme catalyzes the conversion of ATP to cyclic AMP (cAMP), which, in turn, activates a class of enzymes called protein kinases. These kinases transfer a phosphate group from ATP to a substrate molecule in a process called phosphorylation. The phosphorylation of a substrate molecule changes its shape, thereby activating it. This chain of reactions, where hormone binding to the GPCR leads to the appearance of cAMP in the cytoplasm as the second messenger which, in turn, leads to the activation of protein kinase is an example of a “reaction cascade.” In this case, since a signal from the exterior of the cell is transferred to the interior via the formation of a “second messenger,” the process is called “signal transduction cascade.” Other second messengers that can be involved as a result of hormone binding to a cell membrane receptor include cyclic GMP (derived from guanosine triphosphate), tyrosine kinases, inositol phospholipids, and even calcium ions. Cellular responses to hormone binding of a cell membrane receptor include altering membrane permeability, activating metabolic pathways, stimulating synthesis of proteins and enzymes, and hormone release.
The binding of a hormone at a single cell membrane receptor causes the activation of many G-proteins, which can catalyze many reactions simultaneously. Thus, the effect of a peptide hormone is amplified as the signaling cascade progresses. A small amount of hormone can trigger the formation of a large amount of cellular product. To stop hormone activity, the cascading chemical reaction is interrupted; for example cAMP is deactivated by the cytoplasmic enzyme phosphodiesterase (PDE). PDE is always present in the cell, and it breaks down cAMP spontaneously, preventing overproduction of cellular products. The specific response of a cell to a lipid-insoluble hormone depends on the type of receptors that are present on the cell membrane and the substrate molecules present in the cell cytoplasm.
The Pituitary Gland and Hypothalamus
Diagram of the Endocrine System Glands
The pituitary-hypothalamus axis links the nervous system with the endocrine system. The hypothalamus is a region of the brain that is located inferior to the thalamus. It coordinates signals from internal organs and other regions of the brain and regulates a response from the endocrine system via the pituitary. The hypothalamus secretes both releasing hormones that stimulate the anterior pituitary to secrete a hormone and inhibiting hormones that inhibit the release of a hormone from the anterior pituitary.
The pituitary gland is a pea-sized gland located at the base of the brain attached to the hypothalamus via a stalk called the infundibulum. The pituitary gland is primarily regulated by nerve impulses or hormones released by neurosecretory cells of the hypothalamus. The pituitary, in turn, releases hormones that either have a direct effect on target cells or regulate hormone production by other endocrine glands. Those hormones that control the release of another hormone from an endocrine gland are called tropic hormones. The pituitary has two distinct regions: the anterior pituitary, and the posterior pituitary.
The Hypothalamus-Pituitary Complex. This image by OpenStax is licensed under a Creative Commons Attribution License 4.0. Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction
The anterior pituitary secretes seven different peptide or protein hormones: growth hormone(GH), prolactin (PRL), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ATCH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and melanocyte stimulating hormone (MSH). The posterior pituitary is an extension of the brain and releases hormones produced by the hypothalamus. The posterior pituitary releases antidiuretic hormone (ADH) (also known as vasopressin) and oxytocin. The pituitary looks like one gland because the anterior and posterior pituitary do not have externally visible distinctions, but from a cell and tissue perspective, they are really two different and distinct organs.
The anterior pituitary gland, or adenohypophysis, is surrounded by a capillary network. This capillary network is a part of the hypophyseal portal system that carries substances from the hypothalamus directly to the anterior pituitary. Remember that substances such as hormones can only leave or enter the circulatory system at capillaries, and portal systems (portal systems are also found in the digestive system) move material from one capillary bed to another without returning it to the main circulation. Anterior pituitary hormones then enter the capillaries and travel to the heart and through the systemic system in the same way other hormones do.
Several anterior pituitary hormones (TSH, ACTH) are tropic hormones, because they control the functioning of other endocrine glands. While these hormones are produced by the anterior pituitary, their production is controlled by regulatory hormones produced by the hypothalamus. Negative feedback mechanisms regulate how much of these regulatory hormones is released, and how much anterior pituitary hormone is secreted.
The posterior pituitary is significantly different in structure and function from the anterior pituitary. As its name implies, the posterior pituitary is behind the anterior pituitary (toward the back). It contains mostly axons of secretory neurons and neuroglial cells; the cell bodies of these neurons are in the hypothalamus. The posterior pituitary and the infundibulum together are referred to as the neurohypophysis.
The posterior pituitary does not produce hormones, but stores hormones produced by the hypothalamus and releases them into the bloodstream. The hormones antidiuretic hormone (ADH) and oxytocin are produced by neurons in the hypothalamus and transported within these axons along the infundibulum to the posterior pituitary. They are released into the posterior pituitary capillaries in response to neural signaling from the hypothalamus. These hormones are considered to be posterior pituitary hormones, even though they are produced by the hypothalamus, because that is where they are released into the circulatory system.
The thyroid gland possesses two lobes that are connected by the isthmus. It is located in the neck, just below the larynx with the isthmus in front of and lobes lateral to the trachea. It has a dark red color due to its extensive vasculature. When the thyroid increases in size due to dysfunction, it can be felt under the skin of the neck. The main function of the thyroid gland is the synthesis and storage of thyroid hormones that are involved in maintaining metabolic homeostasis.
The thyroid gland is made up of many spherical thyroid follicles, which are lined with simple cuboidal epithelium. These follicles contain a viscous fluid called colloid that stores the glycoprotein thyroglobulin, the precursor to the two thyroid hormones. Thyroglobulin is not normally released into circulation unless the thyroid gland is damaged due to disease or injury. Other endocrine cells, called parafollicular cells, are located between adjacent follicles and produce a different hormone, calcitonin, that is involved in blood calcium homeostasis.
Synthesis of Thyroid Hormones
Unlike most endocrine glands, the thyroid gland stores large amounts of some of the hormones it synthesizes. Thyroglobulin is produced and secreted by follicle cells into the lumen of follicles as a colloid. There it undergoes post-translational modification to produce functioning thyroid hormones. Iodide molecules are added to the thyroglobulin precursor to produce the hormones thyroxine and triiodothyronine. Thyroxine is also known as T4 because it contains four atoms of iodine, and triiodothyronine is also known as T3 because it contains three atoms of iodine. In developed countries, the iodide required for hormone synthesis is obtained primarily from iodized salt. However, seafood and plants grown in iodine rich soil at lower elevations also provide the required iodide. Since iodine as a molecule is quite volatile, the food grown in higher elevations (lower atmospheric pressure) lacks sufficient iodine. Iodide ions are actively transported into the follicular lumen from the capillaries by follicle cells. Follicle cells are stimulated to release stored T3 and T4 from the lumen into the blood capillaries by thyroid stimulating hormone (TSH), which is produced by the anterior pituitary. Follicle cells also begin synthesizing more T3 and T4 in response to TSH stimulation.
Structure of Thyroxine
A third hormone, calcitonin, is produced by parafollicular cells, or C cells of the thyroid. Calcitonin release is not controlled by TSH, but instead is released when calcium ion concentrations in the blood rise. Calcium ions bind to specific receptor on the C cell and stimulate release of calcitonin. Calcitonin acts primarily in children to lower blood calcium levels when levels get too high. Calcitonin causes decreased tubular reabsorption of Ca2+ in the kidneys, leading to calcium loss in urine. It inhibits bone resorption activity of osteoclasts and calcium absorption in intestine to also reduce plasma calcium levels. It is also suspected to have an indirect effect stimulating osteoblast activity and development. However, in adult humans it appears to play only a minor role in calcium homeostasis because abnormalities in calcitonin production do not appear to be associated with specific plasma calcium imbalances. Research has implicated its role during times of high calcium demands, such as pregnancy and lactation.
The four parathyroid glands are each the size of a grain of rice and are usually located on the posterior surface of the thyroid gland. The exact location and number of parathyroid glands can vary from person to person. The parathyroid glands are named for their proximity to the thyroid gland (para- means next to), often seeming to be part of the same gland; however, their cells are distinct from those of the thyroid gland.
Side view of parathyroid glands
Each parathyroid gland is covered by connective tissue and contains many secretory cells called chief cells, which synthesize and secrete parathyroid hormone (PTH). Another type of cell, oxyphil cells, can be distinguished histologically in the parathyroid but they are not clearly understood. They appear to increase during renal failure, but their function is still a subject of clinical research.
PTH is synthesized as a pro-peptide that is cleaved into an active hormone, which is vital in maintaining blood calcium levels. Calcium is required for nerve impulse transmission, for muscle contractions and for many cellular processes–including signal transduction. Therefore, plasma calcium concentrations must be maintained within a narrow normal range of 9–10 mg/dL. PTH functions by increasing blood calcium concentrations when calcium ion levels fall below normal. Calcium ions bind to specific receptors on the chief cell and inhibit release of PTH; when the plasma calcium level falls, PTH secretion is stimulated. PTH stimulates reabsorption of calcium from filtrate during urine formation, increased absorption in the intestines from digested products and increased activity of osteoclasts to release calcium (and phosphate) from bone matrix into the plasma. There is some evidence that it may also indirectly inhibit osteoblast activity.
A parathyroid adenoma is a benign tumor of the parathyroid gland that can cause an overproduction of PTH leading to hyperparathyroidism. Hyperparathyroidism results in hypercalcemia, which can lead to kidney stones. Additionally, increased rate of bone resorption due to higher osteoclast activity due to this condition may also lead to osteoporosis. Usually only one of the four parathyroid glands is affected and can be surgically removed without any adverse effects. However, removal of all the parathyroid glands will cause an imbalance in blood calcium levels resulting in death.
The adrenal glands help regulate the body’s response to stress, controlling blood pressure, and maintaining the body’s water, sodium, and potassium levels. The adrenal glands are associated with the pair of kidneys which are retroperitoneal and lateral to the spinal column ; one gland is located on the superior surface of each kidney (hence they are also known as suprarenal glands). The adrenal glands consist of an outer adrenal cortex (cortex means outer layer) and an inner adrenal medulla (medulla means middle). Functionally and anatomically the adrenal gland is really two glands packaged together. The cells of the cortex are endocrine and those of the medulla are neurosecretory. The cells look very different and embryologically they come from different tissues. These regions secrete different hormones: the adrenal cortex produces steroid hormones, and the adrenal medulla produces catecholamine hormones.
Location of the kidneys, pancreas, and adrenal glands
The adrenal glands have a large blood supply. They receive arterial blood from the renal arteries, the phrenic arteries, and suprarenal arteries from the aorta. Arterial blood enters the adrenal glands at the adrenal cortex and drains into venules in the adrenal medulla. The suprarenal vein of the right adrenal gland drains into the inferior vena cava, and the suprarenal vein of the left adrenal gland drains into the left renal vein.
The adrenal cortex is the outer layer of the adrenal gland and is made up of layers of epithelial cells and associated capillary networks. These layers form three distinct regions that secrete different steroid hormones: the outer zona glomerulosa produces mineralocorticoids (influence salt and water balance), the middle zona fasciculata produces glucocorticoids (impact metabolism and inflammation), and the inner zona reticularis produces androgens (regulate catabolism and sexual characteristics).
The main mineralocorticoid is aldosterone, which regulates the concentration of ions in urine, sweat, and saliva. Aldosterone release from the adrenal cortex can be triggered by a number of things including decrease in blood concentrations of sodium ions, blood volume, or blood pressure, or an increase in blood potassium levels.
The three main glucocorticoids are cortisol, corticosterone, and cortisone. The glucocorticoids stimulate the synthesis of glucose from non-glycogen sources, and they promote the release of fatty acids from adipose tissue. These hormones increase blood glucose levels to maintain levels within a normal range between meals. They are secreted in response to ACTH, and levels are regulated by negative feedback.
Androgens are a class of hormones and that affect sexual characteristics. Testosterone is associated with male sexual characteristics, while progesterone and estrogen are associated with female reproductive function; androstenedione is an intermediate molecule in the synthetic pathways of these and many of the steroid hormones.
Adrenal cortex and medulla
The adrenal medulla is the inner layer of the adrenal glands and contains chromaffin cells, which are large, irregularly shaped cells that are closely associated with blood vessels. These cells are innervated by autonomic (involuntary) nerve fibers from the central nervous system, which allows for quick hormone release.
Chromaffin cells of the adrenal medulla produce epinephrine (adrenaline) and norepinephrine (noradrenaline). Epinephrine is the primary adrenal medulla hormone accounting for 75–80 percent of its secretions. Epinephrine and norepinephrine increase 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.
Both are stored in vesicles or granules in the adrenal medulla, very similar to the way posterior pituitary cells store the neurosecretory hormones from hypothalamus for release. The release of epinephrine and norepinephrine into the blood is stimulated by neural impulses from the sympathetic nervous system. These neural impulses originate from the hypothalamus in response to stress to prepare the body for the fight-or-flight response.
The pineal gland is located between the cerebral hemispheres of the brain. It is attached to the roof of the third ventricle in the diencephalon. The pineal gland consists of secretory cells, called pinealocytes, that secrete the hormone melatonin. Melatonin is derived from serotonin (a neuropeptide) and is regulated in response to the light and dark of the environment (the diurnal cycle). Photons, packets of light, are detected by the retinas of the eyes, which initiate a nerve impulse that is detected by the pineal gland. This mechanism is similar to the process in the posterior pituitary or adrenal medulla. The pineal gland synthesizes the highest levels of melatonin during the night, when light levels are the lowest, and the increased blood concentrations of melatonin makes us sleepy. Blood concentrations of melatonin are lowest during the day, when light exposure inhibits the synthesis of the hormone.
The target cells of melatonin are located in the suprachiasmatic nucleus (SCN) of the brain. The SCN functions as a biological clock that regulates physiological processes such as the sleep-wake cycle, appetite, and body temperature. Melatonin is thought to inhibit the release of gonadotropins from the anterior pituitary, which affect the onset of puberty.
Higher melatonin levels at night make us sleepy, and a disruption in melatonin synthesis can disrupt the sleep cycle. Travel across several time zones can result in disruptions to the sleep cycle, or jet lag. This is due to the change in the dark-light cycle that the body is accustomed to, and it can take several days for melatonin synthesis to adapt to the change. Melatonin supplements are available to treat jet lag as well as other sleep disorders; however, their efficacy has not been conclusively established.
The pancreas is an elongated organ that plays a central role in energy metabolism, storage, and utilization of glucose (carbohydrate). It is located slightly dorsal to the stomach and between the stomach and the small intestine. The tapered distal end lies in contact with the spleen, while the ducts from broader proximal end enter the duodenum at gastro-duodenal junction. The pancreas contains both exocrine cells that excrete digestive enzymes and endocrine cells that release hormones. Approximately 99 percent of pancreatic cells are exocrine cells that are arranged around ducts in clusters called acini (singular is acinus).
The endocrine cells of the pancreas form clusters called pancreatic islets or the islets of Langerhans (islets are small islands) with associated blood capillaries. The pancreatic islets contain two major cell types: alpha cells, which constitute 20 percent of the total mass of the islets and produce the hormone glucagon, and beta cells, which constitute 75 percent of the total mass of the islets and produce the hormone insulin. These hormones regulate blood glucose levels. Alpha cells release glucagon as blood glucose levels decline below the set point. When blood glucose levels rise, alpha cells stop secreting glucagon, and beta cells then release insulin. When blood glucose levels drop below the set point (which does not happen under normal conditions), beta cells stop secreting insulin.
Pancreatic cells also contain two minor populations of cells: delta cells, which constitute 4 percent of the total mass of the islets and secrete somatostatin, and F (or PP) cells, which constitute 1 percent of the total mass of the islets and secrete pancreatic polypeptide. They have specific paracrine regulator effects in the pancreas. Pancreatic polypeptide is secreted after a high protein meal or fasting and inhibits pancreatic exocrine secretion and stimulates gastric juice secretion (opposite effect of cholecystokinin, CCK, of the small intestine). It also stimulates both alpha and beta cells.
Detailed view of the pancreas
The gonads, the male testes (sing. testis) and female ovaries, function in production of gametes (sperm and ovum) and also produce steroid hormones. The testes produce androgens, testosterone being the most prominent. Testosterone stimulates the development of male secondary sex characteristics and the production of sperm cells. The testes also produce the hormone inhibin, which inhibits the release of the tropic hormone from the anterior pituitary follicle-stimulating hormone (FSH) needed for the development of sperm (spermatogenesis).
The ovaries produce the hormones estrogen and progesterone, which stimulate the development of female secondary sex characteristics, regulate the menstrual cycle, and prepare the body for childbirth. The ovaries also produce the hormone inhibin, which inhibits the release of FSH.
The placenta, which supplies the necessary nutrients to the fetus, is also an endocrine organ. It synthesizes and secretes a number of hormones that are crucial for the maintenance of pregnancy. The human chorionic gonadotropin hormone (hCG), that is the basis of urine pregnancy tests is another of the placental hormones. As the fetus develops, the placenta takes over the production of estrogen and progesterone to maintain pregnancy. The high level of estrogen facilitates the growth of the uterus and the mammary glands during gestation. Progesterone is important in suppressing maternal immune response towards the fetus and inhibiting uterine smooth muscle contraction. The placenta also produces relaxin, that affects collagen metabolism and softens the pubic symphysis to facilitate birthing. It also produces lactogen, which is structurally similar to prolactin and growth hormone (pituitary hormones), but its role, if any, in human lactation is still being investigated.
Location of the ovaries and testes
Review of the Endocrine Glands and Hormones
Diagram of the Endocrine System Glands
|Endocrine Gland||Associated Hormones||Main Effect|
|Pituitary (Anterior)||Growth hormone||Promotes growth of body tissues|
|Prolactin||Promotes milk production|
|Thyroid-stimulating hormone (TSH)||Stimulates thyroid hormone release|
|Adrenocorticotropic hormone (ACTH)||Stimulates hormone release by adrenal cortex|
|Follicle-stimulating hormone (FSH)||Stimulates gamete production|
|Luteinizing hormone (LH)||Stimulates androgen/estrogen production by gonads|
|Pituitary (Posterior)||Antidiuretic hormone (ADH; also called vasopressin)||Stimulates water reabsorption by kidneys|
|Oxytocin||Stimulates uterine contractions during childbirth|
|Thyroid||Thyroxine, triiodothyronine||Stimulate metabolism|
|Calcitonin||Reduces blood Ca2+ levels, primarily in children|
|Parathyroid hormone (PTH)||Increases blood Ca2+ levels|
|Adrenal (Cortex)||Aldosterone||Increases blood Na+ levels, and related water conservation by kidneys, Decreases blood K+ levels|
|Cortisol, corticosterone, cortisone||Increase blood glucose levels|
|Adrenal (Medulla)||Epinephrine, norepinephrine||Stimulate fight-or-flight response|
|Pineal||Melatonin||Regulates sleep cycles|
|Pancreas||Glucagon||Increases blood glucose levels|
|Insulin||Decreases blood glucose levels|
|Testes||Testosterone||Stimulates development of male secondary sex characteristics and sperm production|
|Inhibin||Inhibits secretion of FSH|
|Ovaries||Estrogen and progesterone||Stimulates development of female secondary sex characteristics, egg production and preparation of the body for childbirth|
|Inhibin||Inhibits secretion of FSH|
Organs with Secondary Endocrine Function
There are several organs whose primary functions are non-endocrine but that also possess endocrine functions. These include the heart, gastrointestinal tract, kidneys, adipose tissue, skin, and thymus.
Heart and Cardiovascular System
The heart possesses specialized cardiac muscle cells, which are endocrine cells in the walls of the atria. These cells respond to increased blood volume by releasing the hormone atrial natriuretic peptide (ANP). Natrium is the name for sodium in many languages and is the reason that Na is the chemical symbol for sodium. High blood volume causes the cells to be stretched, opening stretch-activated membrane channels, resulting in hormone release. ANP acts on the kidneys to reduce the reabsorption of Na+, causing Na+ and water to be excreted in the urine. ANP also reduces the amounts of renin released by the kidneys and aldosterone released by the adrenal cortex, further preventing the retention of water. In this way, ANP reduces the concentration of Na+ in the blood and causes a reduction in blood volume and blood pressure. Another natriuretic hormone, BNP (misnamed brain natriuretic because it was first isolated from pig brains) from the heart ventricle, enhances the effect of ANP.
Endothelial cells lining the cardiovascular system also have an endocrine function. They produce paracrine endothelin, a vasodilator and stimulator of ANP secretion, and nitric oxide (NO), a vasodilator and inhibitor of ANP secretion.
The digestive system produces several hormones that aid in digestive and metabolic homeostasis. Endocrine cells are located in the mucosa of the GI tract throughout the stomach and small intestine. Hormone secretion is controlled by receptors monitoring the chemical content of the digestive lumen. Some of the hormones produced include gastrin (from stomach), secretin, and cholecystokinin CCK (from small intestine) that act on the GI tract and accessory organs such as the pancreas, gallbladder, and liver. They trigger the release of digestive juices that help to break down and digest food in the GI tract. The GI tract also produces the hormones glucose-dependent insulinotropic peptide (GIP) (from stomach) and glucagon-like peptide 1 (GLP-1) (from small intestine). These hormones are secreted in response to glucose in the intestinal lumen. GIP and GLP-1 target cells are beta cells in the pancreas, which are stimulated to release insulin and alpha cells that are inhibited from releasing glucagon. The stomach also produces ghrelin that mediates hunger, stimulating appetite and growth hormone release.
The liver, as an accessory organ of the digestive system, also has an endocrine function in production of insulin-like growth factor (IGFs) and thrombopoietin (THPO). IGFs work with growth hormone to regulate cell metabolism while THPO triggers the formation of platelets in the blood. The liver also produces prohormones (angiotensinogen and calcidiol, vitamin D) and plasma proteins that transport many of the hormones.
Kidneys and Urinary System
The adrenal glands associated with the kidneys are major endocrine glands, and the kidneys themselves also possess endocrine functions. Renin (‘renal’ generally describes aspects of the kidney) is released in response to decreased blood volume or pressure and is part of the renin-angiotensin system that is responsible for the formation of angiotensin II and ultimately leads to the release of aldosterone. Both angiotensin II and aldosterone then causes the retention of Na+ and water, raising blood volume. The kidneys also release the steroid hormone calcitriol, which is the biologically active form of vitamin D that aids in the absorption of Ca2+. Erythropoietin (EPO) is a protein hormone that triggers the formation of red blood cells in the bone marrow. EPO is released in response to low oxygen levels. Because red blood cells are oxygen carriers, increased production results in greater oxygen delivery throughout the body. The banned substance EPO had been used by athletes at one point to improve performance, as greater oxygen delivery to muscle cells allows for greater endurance. Because red blood cells increase the viscosity of blood, artificially high levels can cause severe health risks.
Adipose tissue is a connective tissue found throughout the body. It produces the hormone leptin (Greek “leptos” means “thin”) in response to food intake. Leptin binds to neuropeptide Y in the CNS neurons, producing a feeling of satiety after eating, thus affecting appetite and reducing the urge for further eating. Note that it has the opposite effect of ghrelin secretion from the stomach, but when leptin levels drop, the brain detects a state of starvation and the feeling of hunger increases. These two hormones are the subject of much research related to obesity.
Skin produces cholecalciferol, which is an inactive hormone form of vitamin D3. It is formed when cholesterol molecules in the skin, in the form of 7-dehydrocholesterol, are exposed to ultraviolet radiation. Cholecalciferol then enters the bloodstream and is modified in the liver to form calcifediol. Calcifediol is then modified in the kidneys to form calcitriol, which is the active form of vitamin D3. Vitamin D plays an important role in bone formation.
Bones not only respond to hormones to maintain blood calcium homeostasis, but recent research shows they also have an endocrine function. Osteocytes have been found to produce two hormones (fibroblast growth factor 23 and osteocalcin) that act on kidney, pancreas and other body tissues influencing Vitamin D and glucose homeostasis.
The thymus is an organ that is found behind the sternum and is most prominent in infants, becoming smaller in size through adulthood, replaced by adipose tissue that continues to produce angiogenic factors. The thymus is part of the immune system, with a role in maturation and immunocompetence of T-lymphocytes. The thymus also produces a group of hormones called thymosins, because they were first discovered from the thymus, but now are understood to be produced by many different tissues in the body. They appear to have an anti-inflammatory effect and stimulate tissue repair. Thymosin is also involved in neuroplasticity, and they may have clinical implications in the treatment of cardiovascular, infectious and autoimmune diseases as well as cancer.
|Organ||Associated Hormones||Main Effect|
|Heart||Atrial Natriuretic Peptide (ANP)||Reduces blood volume, pressure, and Na+ concentration|
|Gastrointestinal Tract||Gastrin, Secretin, and Cholecystokinin||Aid in the digestion of food|
|Kidneys||Renin||Stimulates production of angiotensin II|
|Calcitriol||Aids in the absorption of Ca2+|
|Erythropoietin||Triggers the formation of red blood cells in the bone marrow|
|Adipose Tissue||Leptin||Promotes satiety signals in the brain|
|Skin||Cholecalciferol||Modified to form vitamin D|
|Thymus||Thymosins||Aid in the development of the immune system|
Pituitary Gland Tumor: Introduction | Cancer.Net
ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Pituitary Gland Tumor. Use the menu to see other pages. Think of that menu as a roadmap for this entire guide.
About the pituitary gland
The pituitary gland is a small, pea-sized gland located behind the bridge of the nose and near the brain. It is a part of the endocrine system, which regulates hormones in the body. The pituitary gland is often called the “master endocrine gland,” because it releases hormones that control other glands in the body that affect many bodily functions. The pituitary gland is controlled by the hypothalamus, a small structure in the brain.
A pituitary gland has 2 lobes, the anterior (front) and the posterior (back). Each lobe is responsible for releasing specific hormones.
Hormones released by the anterior pituitary lobe
Thyroid stimulating hormone (TSH) stimulates the thyroid gland, which helps regulate the body’s metabolism.
Adrenocorticotrophic hormone (ACTH) controls the hormones released by the adrenal gland, which supports blood pressure, metabolism, and the body’s response to stress.
Gonadotropins, a family of hormones that include follicle stimulating hormone (FSH) and luteinizing hormone (LH), which stimulate production of sperm in the testicles or eggs in the ovaries. Gonadotropins also regulate the menstrual cycle.
Growth hormone (GH) promotes growth of the long bones in the arms and legs, and thickens the skull and bones of the spine. GH also causes the tissue over the bones to thicken.
Prolactin is normally low in everyone but levels rise when needed to stimulate breast milk production, called lactation, after childbirth.
Lipotropin stimulates the movement of fat from the body to the bloodstream.
Melanocyte stimulating hormone (MSH) regulates the production of melanin, the pigment in skin.
Hormones released by the posterior pituitary lobe
Oxytocin stimulates contraction of the uterus during childbirth and the flow of milk during breastfeeding.
Antidiuretic hormone, also known as vasopressin, increases reabsorption of water by the kidneys and allows a person to stay hydrated.
Types of tumors in the pituitary gland
Cancer begins when healthy cells change and grow out of control, forming a mass called a tumor. A pituitary gland tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread.
Most often, pituitary gland tumors are benign growths called pituitary adenomas. But a pituitary gland tumor can occasionally act like a cancerous tumor by growing into nearby tissue and structures, or rarely, spreading to other parts of the body.
Pituitary gland tumors are not brain tumors. The pituitary gland is located under the brain and is separate from the brain. Pituitary gland tumors are medically classified as “endocrine tumors.”
Both benign and cancerous tumors in this gland can create very serious medical problems by interfering with the normal endocrine function of the pituitary gland. In some cases, this is because the tumor starts in cells that make hormones, so the tumor itself can make too many hormones. Pituitary tumors that produce hormones are called “functional tumors.”
In other instances, a pituitary tumor can cause the gland to produce too few hormones. Also, if a pituitary tumor presses on nearby structures, such as the nearby optic nerves in the eye, it can limit a person’s vision.
The next section in this guide is Statistics. It helps explain the number of people who are diagnosed with a pituitary gland tumor and general survival rates. Use the menu to choose a different section to read in this guide.
Pituitary Adenomas (Tumors) Description and Treatment Options
|Pituitary Gland and Pituitary Tumors | American Association of Neurological Surgeons|
The pituitary is a small gland attached to the base of the brain (behind the nose) in an area called the pituitary fossa or sella turcica. The pituitary is often called the “master gland” because it controls the secretion of most of the hormones in the body. A normal pituitary gland weighs less than 1 gram and is about the size and shape of a kidney bean.
The function of the pituitary can be compared to that of a household thermostat. The thermostat constantly measures the temperature in the house and sends signals to the heater to turn it on or off to maintain a steady, comfortable temperature. The pituitary constantly monitors bodily functions and sends signals to remote organs and glands to monitor their function and maintain the appropriate environment. The ideal “thermostat” setting for a body depends on many factors, including level of activity, gender, body composition, etc.
The pituitary is responsible for controlling and coordinating the following:
- Growth and development
- Organ function (kidneys, breasts and uterus)
- Gland function (thyroid, gonads and adrenal glands
Pituitary Anatomy and Functions
The pituitary is divided into distinct sections: the anterior pituitary gland and the posterior pituitary gland. Each part contains unique cells and releases different hormones that are responsible for specific control duties. The anterior pituitary is formed from the same tissue as the pharynx. The posterior pituitary is formed from an out-pouching of the brain and is actually an extension of the hypothalamus, a region of the brain that is connected to the pituitary gland and controls its function. The hypothalamus and pituitary together comprise the neuroendocrine system.
The anterior pituitary accounts for about 80 percent of the pituitary gland size and is composed of the anterior lobe and the intermediate zone. The anterior lobe is responsible for producing the majority of the signaling hormones released into the blood stream. The posterior pituitary gland develops very early in life and does not produce any hormones on its own. However, it does contain the nerve endings of brain cells (neurons) that arise from the hypothalamus. These neurons produce the hormones vasopressin and oxytocin which are transported down the pituitary stalk into the posterior pituitary. They are stored for later release into the bloodstream.
The pituitary and hypothalamus work together to regulate the daily functions of the body as well as play an essential role in growth, development and reproduction. The hypothalamus secretes two types of hormones (releasing hormones and inhibiting hormones) that control secretion of other hormones from the anterior pituitary. The pituitary gland performs its key functions by releasing several signaling hormones that consequently control the activities of other organs.
The pituitary produces the following hormones:
- Growth hormone (GH) — This is the principal hormone that regulates metabolism and growth.
- Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) — These hormones control the production of sex hormones (estrogen and testosterone) and are important in regulating menstruation in women.
- Melanocyte-stimulating hormone (MSH) — MSH regulates the production of melanin, a dark pigment, through melanocytes in the skin. Increased melanin production produces pigmentation or tanning of the skin. Some conditions causing excessive production of MSH may lead to darkening of the skin.
- Prolactin (PRL) — This hormone stimulates secretion of breast milk.
- Thyroid-stimulating hormone (TSH) – TSH stimulates the thyroid gland to release thyroid hormones. Thyroid hormones control the basal metabolic rate and play an important role in growth and maturation. Thyroid hormones affect almost every organ in the body.
- Vasopressin/Antidiuretic hormone (ADH) — This hormone promotes water retention.
Pituitary adenomas are the fourth most common intracranial tumor after gliomas, meningiomas and schwannomas. A large majority of pituitary adenomas are benign and are relatively slow growing. Adenomas are by far the most common disease affecting the pituitary gland. These tumors most commonly affect people in their 30s or 40s, although they can be diagnosed in children as well. Most of these tumors can be successfully treated. Pituitary tumors can vary in size and behavior. Tumors that produce hormones are called functioning adenomas, while those that do not are called nonfunctioning adenomas.
Tumors smaller than 10 millimeters are called microadenomas and often secrete anterior pituitary hormones. These smaller, functional adenomas are usually detected earlier because the increased levels of hormones cause abnormal changes in the body. Approximately 50 percent of pituitary adenomas are diagnosed when they are smaller than 5 millimeters in size. Adenomas larger than 10 millimeters (the size of a dime) are called macroadenomas and usually do not secrete hormones. These tumors are often discovered because they produce symptoms by “mass effect,” compressing nearby brain or cranial nerve structures.
The symptoms of a pituitary tumor, other than mass effect, generally result from endocrine dysfunction. For example, this dysfunction can cause overproduction of growth hormones, as in acromegaly (gigantism), or underproduction of thyroid hormone, as in hypothyroidism. Hormonal imbalances can impact fertility, menstrual periods, heat and cold tolerance, as well as the skin and body in other ways.
Because of the pituitary gland’s strategic location within the skull, tumors of the pituitary can compress important brain structures as they enlarge. The most common circumstance involves compression of the optic nerves leading to a gradual loss of vision. This vision loss usually begins with a deterioration of peripheral vision on both sides.
The presence of three or more of the following symptoms may indicate a pituitary tumor:
- Vision problems (blurred or double vision, drooping eyelid)
- Headaches in the forehead area
- Nausea or vomiting
- Impaired sense of smell
- Sexual dysfunction
- Growth problems
- Unexplained weight gain
- Unexplained weight loss
- Easy bruising
- Aching joints
- Carpal tunnel syndrome
- Disrupted menstruation
- Early menopause
- Muscle weakness
- Galactorrhea (spontaneous breast-milk flow not associated with childbirth or the nursing of an infant)
When a pituitary tumor is suspected, a physician will perform a physical examination as well as vision testing to detect visual field deficits, such as loss of peripheral vision. Hormone testing of the blood and urine and imaging studies of the brain are used to confirm diagnosis. The most accurate diagnostic imaging test is magnetic resonance imaging (MRI), performed with and without a contrast agent.
Early intervention provides the best chance for cure or control of a pituitary tumor and its side effects. There are three types of treatment used for pituitary tumors: surgical removal of the tumor, radiation therapy using high-dose x-rays to kill tumor cells and medication therapy to shrink or eradicate the tumor.
The transsphenoidal approach involves accessing the tumor through the nasal cavity using either a microsurgical or endoscopic approach, whichever the surgeon prefers. Surgery is usually combined with the use of computer guidance, allowing a minimally invasive approach. Transsphenoidal surgery is invariably the procedure of choice in small “functional” adenomas and in most macroadenomas, with the exception of prolactinomas. In prolactinomas (prolactin hormone-secreting microadenomas or macroadenomas), the use of a specific dopamine agonist medication is generally advised with surgery reserved for those tumors failing to show a good response to the treatment. Transsphenoidal surgery is generally very well tolerated because of its minimally invasive characteristic, few side effects and quick patient recovery. Patients can often leave the hospital as early as two to three days after surgery.
The transcranial approach, or craniotomy, is less commonly used and reserved for particularly large and invasive tumors which cannot be safely removed through the transsphenoidal route.
Radiation therapy uses high-energy x-rays to kill abnormal pituitary tumor cells. Radiation is extremely effective in stopping tumor growth and, with time, will lead to tumor shrinkage. Radiation therapy may be an option if the tumor cannot be treated effectively through medication or surgery.
There are three types of radiation suggested:
Standard External Beam Radiotherapy
Standard external beam radiotherapy uses a form of radiation called photons. These photons are generated by the use of a linear accelerator. Treatment is generally delivered in fractions, one treatment or “fraction” a day, five days a weeks for four to five weeks.
Proton Beam Treatment
Proton beam treatment employs a different type of radiation called protons. Proton therapy can generally be more targeted than photon therapy, with the ability to deliver higher doses of radioactivity. Higher doses of radiation carry a better chance of tumor control but also a higher risk of injury to surrounding normal brain tissue.
Stereotactic radiosurgery (Gamma Knife, Novalis BrainLab and CyberKnife) combines standard external beam radiotherapy with a technique that focuses the radiation through many different ports. This treatment tends to sustain less damage to tissues adjacent to the pituitary and can be delivered in fewer sessions.
Prolactinomas are the most common secreting pituitary adenoma seen clinically. In general, medical therapy is the first course of treatment. With medical management, about 80 percent of patients have prolactin levels restored to normal through dopamine agonist therapy. The most commonly used agents are bromocriptine or cabergoline. The size of the tumor will be reduced in the majority of patients to varying degrees, often resulting in improved vision, resolution of headaches and restored menstruation and fertility in women.
Cabergoline is currently the most commonly used of the two drugs, having less side effects and usually requiring only a twice a week dosing schedule. Bromocriptine requires a once a day dosing regime and generally has more side effects including gastrointestinal upset, nausea and dizziness with getting up too fast. Cabergoline has also been shown to be effective in patients who are resistant to bromocriptine therapy.
In patients with microadenomas, dopamine agonist therapy is usually attempted first for a period of several months. If the tumors do not respond to medication therapy, then surgery is considered. In general, the recommendation is that it is done within six to 12 months of the start of the medication therapy.
Medications used in the treatment of other functional adenomas include:
Growth hormone-secreting tumors (Acromegaly/Gigantism)
ACTH-secreting tumors (Cushing’s syndrome/disease)
The AANS does not endorse any treatments, procedures, products or physicians referenced in these patient fact sheets. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific neurosurgical advice or assistance should consult his or her neurosurgeon, or locate one in your area through the AANS’ Find a Board-certified Neurosurgeon online tool.
90,000 ELISA studies of the thyroid gland and other systems
Most of all processes in the human body are controlled by hormones – special biologically active substances of various chemical structures. The growth of muscles, the level of metabolism and even the question of a person’s sex largely depend on their number and rate of excretion. Most of the hormones begin to be produced in the body during the period of intrauterine development, determining the characteristics of the development of the embryo.For example, when the production of female sex hormones and receptors for them prevails in the embryo, a girl is born. If there is a predominance of male hormones, this leads to the development of the body according to the male type. However, the influence of this group of biologically active substances does not end at the stage of determining the sex of a person, because it is the sex hormones that further control the implementation of one of the most important functions of the human body – the birth of healthy offspring. We can say that they form this process “from and to” – from sex determination and the formation of organs of the reproductive system to the emergence of sexual desire and bearing a child in a woman.Therefore, the role of female sex hormones in family planning and conception is extremely important. Suffice it to say that almost half of all cases of infertility in women are due precisely to endocrine reasons – that is, violations of the release and work of various hormones.
In this regard, in case of difficulties with conception, any doctor first of all will prescribe a study of the amount of hormones in the woman’s blood .
In addition to family planning, the importance of female sex hormone testing affects many other medical specialties.
In addition to endocrinologists, oncologists, gynecologists, mammologists, orthopedists and nephrologists may be interested in the results of such a study. This is due to the fact that any system of hormones in the human body forms many interconnections with other systems of the body, therefore, a violation in one link of this chain inevitably leads to a whole cascade of pathological reactions.
The first item on the list of indications for such a study is the issue of family planning.It is female infertility that often forces a person to see a doctor, while with other indirect symptoms of hormonal imbalance (obesity, painful menstruation or an irregular cycle, changes in the structure of hair, skin, nails), a woman usually tries to cope on her own without a doctor’s recommendation. Thus,
it is worth donating blood to the level of female sex hormones if it is impossible to conceive a child for six months or more . Such a long period is due to the fact that even against the background of the full health of both partners, it is far from always possible to have a child right away – the favorable period for this is only about a week a month.The body also carefully prepares for this process, therefore, sometimes due to stress at work, unfavorable meteorological conditions, pregnancy may not occur in one favorable period of ovulation and occur in the next. However, a six-month period of fruitless attempts is considered sufficient to suspect violations in the reproductive system of one of the partners. Statistically, the reason for this is precisely the endocrine disorders in women, so they are checked in the first place.In addition to family planning problems, the analysis for female sex hormones is recommended for the following pathological conditions and phenomena:
Miscarriage, miscarriages, spontaneous abortions – a violation of the course of pregnancy, as well as problems with conception, arise against the background of a pathological level of hormones. Therefore, if such phenomena have occurred in the past, during a new pregnancy, it is necessary to regularly conduct a blood test for the content of these biologically active substances.In this case, if the level of hormones is disturbed, you can start a timely drug correction to save the child.
Irregular menstrual cycle and painful or heavy periods, as well as in their absence (amenorrhea). In case of any violations of the hormone system in a woman, the picture of the menstrual cycle will invariably change, since its course is completely controlled by the endocrine system. In addition, the hormonal blood picture is examined for diseases of the reproductive system – polycystic ovaries, uterine tumors.With discomfort in the mammary glands, pain, discharge, the presence of seals in the chest. Some female sex hormones stimulate breast growth and secretion. Therefore, the described complaints may be the result of changes in the level of biologically active substances in the blood. Violation of hair growth – baldness (alopecia) or, on the contrary, strong hair growth and male-pattern hair growth in a woman. These phenomena directly indicate violations in the sex hormonal sphere. An increase in body weight, especially not due to diet or lifestyle, can be a symptom of various endocrine diseases, including reproductive disorders.Decreased libido, disorders in the intimate sphere, sexual perversion – all this can also be a consequence of the pathological release of hormones. In the treatment of various diseases with the help of hormonal drugs, the level of hormones in the blood is monitored in this way. In addition, the analysis of the level of female sex hormones can be prescribed to men – in fact, their “female” identity is just a tribute to history. It has now been found that many of these substances play an active role in the development of the male body, including the formation of its reproductive system.Just like the typically “male” hormone, testosterone is also present in the female body and performs a number of functions in it, so the study of its level is also included in the scope of such an analysis. Signs of a violation of the amount of these biologically active substances can be gynecomastia (growth of mammary glands in men), some forms of impotence, decreased libido (libido), tumors and other damage to the organs of the endocrine system. The study of hormone levels is also used in the case of children and adolescents.Signs of premature puberty or delayed puberty in adolescents may be the main reasons for performing this analysis. Features of the analysis and preparation for the study The most important feature of the blood test for the level of sex hormones is the fact that blood sampling does not occur simultaneously. This is due to the fact that their amount in the blood is constantly changing, which makes it difficult to form a table of norms for each hormone. The biological reflection of such hormonal surges is the menstrual cycle, for this reason the most convenient moment for analysis for various biologically active substances is determined with its help.Previously, each individual hormone had its own “ideal day”, which forced a woman to donate blood many times over the course of a month. Today, there is a technique by which a blood test is performed three times per cycle – with each of them, the picture of the level of a certain group of female sex hormones is revealed.
A woman does not have to pass all three tests – in this matter, it all depends on the position and opinion of the attending physician. For example, if he needs to know the level of estrogen, he will assign her a single study on the most favorable day of the cycle.However, in some cases, a complete picture of all sex hormones in the blood is needed, which requires an obligatory test three times in one cycle. The calculation of the cycle, as you know, begins from the beginning of menstruation – the first day of menstruation is also the first day of the menstrual cycle. If a woman, when contacting a doctor, does not remember the date of the last menstruation, then the doctor will appoint her an appointment at the next new beginning of the cycle. After that, the blood donation procedure takes place in the following order:
The third-fifth day of the cycle – blood is donated to study the level of follicle-stimulating hormone (FSH) and luteinizing (LH) hormones, as well as prolactin.
The eighth to tenth day of the cycle is the most convenient time to determine the level of testosterone and its precursor DHEA-s (dehydroepiandrosterone sulfate)
Twenty-first to twenty-second days – the amount of progesterone and estradiol is investigated.
There is another approach to determining the normal level of each hormone – by the phase of the menstrual cycle. According to this method, for each biologically active substance, there are separately at least six indicators of the norm for the phases of the cycle for the ovary and other factors:
Follicular phase – from the first to the fourteenth day, the time of the formation of the follicle with the egg;
Ovulatory phase – from the fifteenth to the eighteenth day – the time of release of the egg from the follicle.It is during this period that the chance of conception is highest, and there is a sharp surge in the level of all hormones, with the exception of progesterone.
Luteal phase – from the nineteenth to the twenty-seventh (end of the cycle and the beginning of menstruation). During this period of time, first an increase (the first half of the phase) occurs and then a gradual decline in the level of progesterone.
The level of hormones when using oral contraceptives – the use of hormonal contraceptives “freezes” the menstrual cycle and the level of hormones is at the same level, not experiencing special fluctuations.The amount of biologically active substances in postmenopause – after the end of the reproductive period, the hormonal background changes, but sharp changes in the level are not characteristic. This method of determining the amount of female sex hormones does not require waiting for a special period for blood sampling, but you still need to roughly know the day of the cycle to determine the phase. In addition, this method requires high qualifications of the doctor so that he can understand the complex relationships of hormones at different periods of the menstrual cycle.Naturally, men, children and women in postmenopausal women do not have a menstrual cycle, therefore, the above restrictions and difficulties in no way apply to this group of patients. Preparation for the delivery of such an analysis by and large does not differ from that with other methods of laboratory diagnostics. It is necessary to exclude the use of caffeinated drinks, alcohol, fatty and heavy foods a day before blood sampling. Blood is taken in the morning on an empty stomach. Recommendations about restricting sexual activity before taking the analysis are devoid of reason – on the contrary, it is better to maintain a habitual way of life, including in the intimate sphere.This will help the doctor determine the woman’s baseline hormone levels. Decoding the analysis results As already mentioned, decoding the analysis is a certain complexity , since this indicator can vary greatly depending on the phase of the menstrual cycle, emotional state, even on the time of day. So, follicle-stimulating hormone is released into the blood not continuously, but in separate bursts every three to four hours. During the period of its release, the concentration of this hormone in the blood can increase sharply (up to two times), which cannot but affect the results of the study.Therefore, the data of the tables presented below are presented in the case of a woman donating blood during the period most favorable for determining a particular hormone.
Follicle-stimulating hormone (FSH) is a hormone of the anterior pituitary gland, its release depends on the effect of another biologically active substance – gonadoliberin, which is formed in the hypothalamus. It performs important functions in both the female and male body: In women, it is responsible for the formation of the follicle – a special formation of the ovaries, which is necessary for the proper maturation of the egg.Once a month, a follicle begins to form in one of the ovaries under the action of this compound, which then ruptures, releasing an egg (ovulation) – this process takes the entire first half of the menstrual cycle. The rest of the follicle turns into a corpus luteum, which produces progesterone. If conception does not occur, then the corpus luteum is destroyed, but in case of pregnancy, this formation releases progesterone throughout its entire period. In men, this hormone contributes to the formation of a number of structures of the reproductive system – seminiferous tubules, testicles.In addition, FSH in men promotes the conversion of estrogens into testosterone, increases the level of male hormones in the blood. Changes in the level of this hormone indicate various types of reproductive disorders in both sexes.
Luteinizing hormone (LH) – like FSH is secreted in the anterior pituitary gland under the influence of hypothalamic gonadoliberin. This hormone is designed to ensure the normal course of ovulation in women, therefore, the main peak of its level is observed on the eve of this phenomenon.In men, this compound controls the normal course of spermatogenesis and the formation of testosterone. In addition to the absolute level of this substance, an important indicator is its ratio with follicle-stimulating hormone. In men and girls before puberty, the index of this ratio is one, while in women of reproductive age, the amount of FSH should exceed the level of LH by 1.5-2 times.
Prolactin is the main hormone that ensures the growth of mammary glands in adolescence, and then actively stimulates lactation, that is, the release of milk.For this reason, its level in the body of men or non-pregnant women is quite low. However, the study of its level is important for several reasons: In the case of pregnant women – its amount must be known for the prognosis and prevention of possible problems with feeding; One of the types of hormone-active tumors – prolactinoma – is just diagnosed by the increased level of this compound.
Testosterone is historically considered a typical male hormone, and for good reason – it stimulates the growth of muscles, facial hair, even a change in voice.But some of its quantities are also present in the female body, where it is secreted by the cells of the ovarian reticulum and the adrenal glands. The study of its level is carried out in the presence of certain symptoms (hirsutism, coarsening of the voice, etc.) in women – its increased amount can be the cause of infertility, as well as a symptom of a condition such as polycystic ovary. In men, a decrease in its amount is accompanied by a disorder of the reproductive system and genital area.
DHEA-s or dihydroepiandrosterone sulfate is a precursor of testosterone, most of which is located in the adrenal glands.This compound is a reserve form of the hormone that is released when needed. Its predominant location in the suprarenal glands has diagnostic value. This allows you to determine the root cause of the increase in testosterone levels. If, against the background of a high content of the male hormone, a low amount of DHEA-s is observed, it means that the cause of the pathology is in the ovaries (for example, polycystic disease). With a simultaneous increase in both indicators, adrenal disease is diagnosed.
Estradiol – is one of the main female sex hormones, which ensures the development of all secondary sexual characteristics. It also controls, along with luteinizing hormone, the normal course of ovulation and the fertilization process. Its effect also affects the psychological state of a woman – it is this substance that is largely responsible for the sexual desire in the fair sex. Men also have minimal amounts of this substance in the blood, but its role in a healthy body is not fully understood.It is assumed that he is just an intermediate for the synthesis of testosterone. With some diseases in men, it can increase.
Progesterone is one of the most important pregnancy hormones. It is with the lack of this substance that the overwhelming number of cases of infertility or miscarriage is associated. This allows it to be used to treat similar conditions. Basically, progesterone is secreted by the corpus luteum (the remainder of the follicle remaining after ovulation), the main increase in its level is observed in the second half of the menstrual cycle.If conception and pregnancy occurs, the amount of this substance remains high enough throughout the gestation period. In the absence of this phenomenon, the level of progesterone slowly decreases to baseline by the beginning of menstruation.
The analysis of sex hormones is a very informative method of clinical research, affecting the interests of doctors in many specialties. Therefore, it is worth a very responsible approach to its implementation and deciphering the results.
90,000 treatment in Moscow, symptoms and diagnosis
Description of the disease
Pituitary adenoma is a benign tumor characterized by uncontrolled growth of the cellular elements of the pituitary gland.As the adenoma grows, the adjacent structures are compressed, which leads to the development of visual disturbances, hydrocephalus
Symptoms of pituitary adenoma
Functioning adenomas are responsible for symptoms depending on which hormone they overproduce.
As the adenoma grows, it compresses the normally functioning areas of the pituitary gland, thereby reducing the level of certain hormones, as well as nearby anatomical structures, which determines some of the symptoms.
Symptoms associated with compression of adjacent anatomical structures
- loss of vision, partial loss of visual fields 90 100
Symptoms associated with changes in hormone levels
Large tumors can lead to hormone deficiency. Deficiency signs:
- nausea, vomiting 90 100
- feeling of weakness 90 100
- inability to keep warm
- sexual dysfunction 90 100
- change in the menstrual cycle or its termination 90 100
- increase in urine volume 90 100
- unmotivated weight loss or gain 90 100
Functioning tumors begin to produce excess hormones.Different types of adenomas lead to the development of specific symptoms, and sometimes a combination, depending on which hormone is produced by the tumor.
Adrenocorticotropic hormone. This hormone stimulates the production of cortisol. Symptoms include the following:
- Accumulation of adipose tissue in the abdomen and cervical spine 90 100
- face rounding 90 100
- weight loss of arms and legs, muscle weakness 90 100
- increase in blood pressure
- increase in blood glucose 90 100
90 099 acne, stretch marks 90 100
- fragility of bones 90 100
- anxiety, irritability, depressive states 90 100
A growth hormone.A tumor that produces this hormone is the cause of the development of acromegaly and can be characterized by the following symptoms:
- increase in the size of arms and legs 90 100
- hardened facial features 90 100
- excess sweating 90 100
- high blood glucose 90 100
- cardiac pathology
- joint pain
- bite change 90 100
- Enhanced hair growth throughout the body 90 100
Prolactin.Prolactin-producing tumors lead to an imbalance of sex hormones – a decrease in the production of estrogen in women and testosterone in men. Prolactinoma is characterized by the following symptoms:
- menstrual irregularity 90 100
- discharge from the mammary glands 90 100
- erectile dysfunction 90 100
- Reduced semen production 90 100
- gynecomastia (enlargement of the mammary glands in men) 90 100
Thyroid-stimulating hormone.As a result of excessive production of thyroid-stimulating hormone by the tumor, the production of the thyroid hormone thyroxine by the thyroid gland increases, which leads to the development of the following symptoms:
- weight loss
- increased heart rate 90 100
90 099 nervousness, irritability 90 100
- Frequent bowel movements 90 100
- excessive sweating 90 100
A pituitary adenoma is often not immediately diagnosed because the symptoms of tumor growth resemble those of other diseases.
The diagnosis of “Pituitary adenoma” is made on the basis of patient complaints, clinical presentation, description of characteristic symptoms, as well as on the basis of the following studies:
- CT or MRI scans of the brain to assess the location and size of the tumor 90 100
- general analysis of blood and urine
- determination of the nature of vision 90 100
In addition, your doctor may refer you to an endocrinologist for a more advanced diagnosis of hormonal levels.
Treatment of pituitary adenoma
The method of treating pituitary adenoma depends on the type of tumor, its size and the degree of pressure that is exerted on adjacent anatomical structures. The determining factors are also the patient’s age and concomitant diseases.
The treatment algorithm is determined by a team of doctors – a neurosurgeon, endocrinologist, oncologist-radiologist.
There are two main surgical techniques for removing a pituitary adenoma:
- endoscopic transnasal transsphenoidal approach.In this case, the tumor is removed through the nose and sinuses 90 100
Transcranial (external access) is used for larger tumors
High-energy radiation sources are used for targeted destruction of tumors.
In some cases, medications prescribed by a doctor block excess hormone production; in others, they inhibit tumor growth.
For prolactin-producing tumors, cabergoline and bromocriptine are prescribed, for ACTH-producing tumors – ketoconazole, mitotane, metirapone, pasireotide, tumors producing growth hormone – somatostatin and lanreotide analogues.
In some cases, a diagnosed pituitary adenoma does not cause symptoms. The patient is recommended to regularly visit doctors in order to control tumor growth and control hormonal levels.
PLEASURE HORMONES: HOW TO GET THEM
22 January 2021 10:01
Dopamine, serotonin, endorphins.How to get more “pleasure hormones” without hurting yourself?
The human body produces many substances that cause pleasant sensations: pleasure, good mood, euphoria. All these substances biochemists call neurotransmitters, because they are responsible for the transmission of nerve impulses.
However, in common parlance, many for some reason call dopamine, serotonin and endorphins hormones of pleasure.
The question arises – how can a person get more of these “hormones” and not harm their health?
Dopamine: my favorite
Dopamine carries out the transmission of nerve impulses in the mesolimbic pathway of the brain, which is responsible for the manifestation of pleasure.The higher the dopamine level, the brighter the sensation.
Serotonin, dopamine, endorphins – these substances are often called pleasure hormones. How do they work?
No one will deny themselves pleasures. Therefore, people tend to raise their level of dopamine in the brain. However, not everything is so simple here.
The simplest idea seems to be to take dopamine as a medicine. But he is not only a neurotransmitter responsible for the transmission of nerve impulses, but also a normal hormone that affects the work of the heart.And drinking heart remedies just for pleasure is extremely dangerous.
On the other hand, substances that cause the production of dopamine in the neurons of the mesolimbic pathway are widespread. These are alcohol and nicotine. In addition, other components of tobacco smoke, as well as some drugs (such as cocaine), block the breakdown of dopamine after they have the expected effect – and the level of pleasure in the brain increases.
However, alcohol, nicotine and other drugs are so named because they cause addiction, in addition to other serious health consequences.So the pleasure gained is bought at too high a price.
In addition, giving up stimulants with an already formed addiction leads to so-called withdrawal, so it is better not to start at all.
What then remains? That which brings joy. For example, a strong release of dopamine causes sex with a loved one. Music and any other pleasing activities produce approximately the same effect. By the way, even thinking about an upcoming pleasant business triggers the release of dopamine.
Serotonin: food and solar cells
If dopamine is a “pleasure hormone,” then serotonin is a “good mood hormone.”Its release in the body leads to improved mood and increased physical activity. But the lack of serotonin – to depression and depression.
There are drugs that increase the level of serotonin in the body. This is exactly what antidepressants do: they block the reuptake of serotonin at synapses after serotonin has completed its function. But in no case should you use them without a doctor’s prescription. It is very easy to overdose without individual prescription, and an excess of serotonin in the body can even lead to death.Plus, unlike dopamine, serotonin levels can be raised more or less safely by eating something suitable. The fact is that serotonin is formed in the body from the amino acid tryptophan, and that is why foods rich in tryptophan (for example, dark chocolate, nuts, dates and bananas) lead to some emotional uplift. A kind of natural antidepressant.
However, remember that these foods are high in fat or sugar. Therefore, eating chocolate bars or bananas in kilograms to improve your mood is not worth it.But for eating tomatoes, which are also rich in tryptophan, there are no such restrictions.
Cause an increase in serotonin levels and sweetness. Here, the chemical path from food to the brain is longer: glucose entering the composition of carbohydrates causes the release of insulin into the blood, which stimulates the breakdown of proteins into amino acids in tissues, and, accordingly, an increase in the level of tryptophan in the blood.
But there is danger here too. First, excess carbohydrates leads to excess weight. And, secondly, there is a chance to get “sweet tooth syndrome”: the body quickly gets used to the fact that sweets lead to an increase in serotonin levels, and with any hint of depression requires as much additional sweets as possible.In addition, the synthesis of serotonin in the body is stimulated by itself – thanks to sunlight. That is why many are depressed if they are nocturnal, or in winter. So it is useful to take most of the vacation not in the summer, when there is so much sun, but in the cloudy season – in late autumn and winter. Leave where the daylight hours are still long enough.
Just don’t get carried away with tanning. Sunburn and melanoma are too high a price to pay for the excess of serotonin, and it can be light where the temperatures are low for visiting the beach.Endorphins – a gift for pregnant women
Endorphins are produced by the body in response to stress in order to reduce pain. By binding to the so-called opiate receptors, they suppress pain and induce euphoria – a kind of reward for the body for getting rid of pain.
Many drugs (opium, for example) – work in the same way, it’s not for nothing that the receptors are called opiate. Only drugs are stronger and have time to bind to receptors first.
However, artificial stimulation of opiate receptors, as in the case of dopamine, causes rapid and persistent dependence.And, as soon as the artificial stimulant disappears, the body starts to have problems – both with pain and with euphoria. The so-called withdrawal syndrome is triggered: the appearance of symptoms that the substance worked to eliminate.
Is there a way to increase the amount of endorphins in the body without harming the body? Of course there is. Firstly, biochemists have the opinion that the euphoria from contact with works of art and the euphoria of orgasm are of an endorphin nature.
Secondly, a small amount of endorphins are produced during moderate exercise.This is how the body prepares itself for stress, which is stress. To increase endorphins, long-term regular exercise is required. There is even such a term – “runner’s euphoria” – a state of light emotional uplift during a long run. Therefore, run, jump and dance for your pleasure – in the truest sense of the word.
Well, and thirdly, nature has made a gift to all women – starting from the third month of pregnancy, endorphins enter the bloodstream. Nice bonus!
90,000 Chemistry of mood: how emotions arise in the body and what to do about it :: Health :: RBC Style
© Kinga Cichewicz / Unsplash
15 February 2018
Biologist and journalist Varya Barkalova explains how the mechanisms that are responsible for our mood work, and which of these processes we can take control of.
Emotion is a psychophysiological process: it is not only the experiences that we experience in response to some event, but also the entire physiological “substrate” – what is happening in the body at this time.
The emotional process has three components: experience (awareness at the level of the psyche), physiological processes in the nervous, endocrine, respiratory and other systems of the body, as well as “response” – a complex of expressing emotions, for example, in the form of facial expressions, laughter or crying.
That is, when the body reacts to some stimulus, reactions are triggered that ultimately lead to the manifestation of emotions. But the same reactions can be triggered in other ways, such as chemicals or other body processes that affect similar metabolic pathways.
This means that we can experience sadness or joy for no apparent reason. The absence of a “real reason” for sadness does not make the experience itself fake. But understanding how and why it occurs will help to control unwanted emotions and not be ashamed of them if it did not work out.
We analyze what is behind our emotions and what internal and external factors can affect them.
Internal processes: hormones and neurotransmitters
All organs in our body do not work by themselves.They are subject to neurohumoral regulation: all processes are controlled by the nervous system and the hormone system associated with it. Emotions are no exception. Hormones not only control the growth and functioning of cells, tissues and organs, but also serve as neurotransmitters – “mediators” between the nervous system and the body.
- Fast reactions. When the body needs to react immediately – in case of danger or if the situation catches us by surprise – the level of adrenaline in the blood rises sharply. This is a “stress hormone”, it is responsible for the mobilization of the body.When the brain assesses the situation as stressful, neurons transmit a command to the adrenal glands – the glands that synthesize adrenaline. You may be familiar with the feeling of being “hot.” It is the adrenal glands that secrete adrenaline, and it is instantly carried through the body by the blood. Evolution has laid down a complex of reactions that must occur in a living creature to help it avoid danger: under the influence of adrenaline, mental activity, nervousness, anxiety and anxiety increase. Adrenaline raises your heart rate and increases muscle tone.
Tip. The popular advice to breathe deeply to calm down is not accidental: the heart rate is directly related to breathing, deep long exhalations (do not inhale!) Calm the heartbeat, and the body slowly triggers reactions inverse to adrenaline arousal.
- Pleasure and encouragement. The adrenal glands produce another important substance, dopamine. In terms of chemical structure, it is close to adrenaline (strictly speaking, adrenaline is “made” from dopamine molecules), but it acts differently.Dopamine is involved in the body’s “reward system”: it is produced when the body does something useful for itself, such as having sex (important for procreation) or eating sweet food (gets a lot of energy), and fixes the action in the mind as pleasant. Thus, it is this neurotransmitter that is responsible for the feeling of pleasure. Since a person is social and highly developed enough to experience pleasure not only from sexual intercourse and eating, the “reward system” works in other situations, including communication with loved ones, success in creativity and much more.Unlike artificial stimulation of this system (for example, with the help of drugs – analogs of dopamine), repetition of pleasant situations does not dull it.
Serotonin is also responsible for a positive state and joyful emotions. Compared to dopamine, it has a different structure and functions in a different way. While dopamine induces feelings of pleasure up to euphoria, serotonin is responsible for the feeling of confidence and calmness. It is its lack that leads to depressive states, and many antidepressants just work with serotonin metabolism: they block its reuptake receptors, and serotonin molecules circulate in the blood longer.
Tip . It sounds trite, but it is doing what you love that causes the longest and most stable release of dopamine and, accordingly, a feeling of satisfaction. Take the time to do what you really enjoy.
- Hormonal background. Women’s bad mood is often attributed to “hormones,” but what is behind this generalization? The hormonal background – the concentration and relative content of various hormones in the blood – is cyclical, and there are several such cycles, each of a different scale.The fastest is the daily cycle. It involves growth hormone, testosterone and cortisol. The latter is also called the stress hormone, but it works differently than adrenaline in a stressful situation. In the morning hours, the concentration of cortisol rises, due to which the heart rate increases and carbohydrate metabolism is activated, and the body receives a “push” to awaken. By the evening, the amount of cortisol drops, and we become less active, but calm. If you do not get enough sleep for a long time or force the body to work “for wear and tear”, the daily hormonal cycle gets lost, which, in turn, leads to increased sleep problems and other consequences, including emotional ones: unreasonable fears and anxiety, despondency, apathy.Chronic stress occurs – a vicious circle that is sometimes difficult to break without outside intervention.
Tip. It is important to understand that in such situations it is pointless to scold yourself for negative emotions and say “Pull yourself together!”, But it is better to seek medical help.
- Circadian rhythm and lighting. Melatonin is responsible for the general regulation of the circadian rhythm. This is the substance that controls our “biological clock”. Although it is not a neurotransmitter and does not directly affect the nervous system, it releases many other substances, including dopamine and serotonin.Experiments have shown that melatonin injections relieve stress, reduce anxiety and generally remove negative emotions. However, melatonin has such a broad effect on the body that the path of its influence is difficult to trace. Its deficiency leads to a number of negative consequences, mostly not in the emotional sphere, including premature aging and an increased risk of tumors. Excess is also not helpful and can lead to depression. The synthesis and release of melatonin depend on lighting: an excess of light decreases its production, and a lack of light increases it.In humans, 70% of the daily secretion of melatonin is accounted for at night.
Tip. Make sure your sleep is comfortable. Reduce artificial lighting in the evening before bed and minimize light noise at night. If outside light bothers you at night, consider using blackout curtains or rearranging your bedroom.
© Michał Grosicki / Unsplash
- Hormones and menstruation. Another hormonal cycle is associated with the menstrual cycle in the female body. The hormones that every month prepare the body of a woman of reproductive age for conception also affect the psyche. However, their effect on emotions is often overrated. The hormones that work during the cycle – estrogens, luteinizing and follicle-stimulating hormones, and others – are not neurotransmitters and cannot directly evoke emotions. A fair amount of negative feelings during menstruation itself appears for indirect reasons: due to constant pain, faintness and general weakness.The brain receives similar signals during illness and inhibits any excitement. And the reasons why severe premenstrual syndrome occurs are still not exactly known.
Tip. If you know you will experience mood swings on certain days, try to create the most comfortable environment for your body and mind. Avoid additional stress from the outside: cyclical changes in the body are stress in themselves.
- Hormonal changes. Hormonal activity changes throughout life. Changes occur in both the male and female body, but in women they are expressed more actively in the form of the onset of menopause. This is a natural process associated with the cessation of estrogen secretion. As in the case of the menstrual cycle, the onset of menopause can be tolerated in different ways – from completely asymptomatic to significant changes in the body and severe mood swings.
Tip. Hormone replacement therapy effectively combats negative symptoms of menopause.It involves taking small doses of hormones – estrogens, progestins and sometimes androgens: their ratio and dosage are prescribed by the doctor based on the results of biochemical analysis.
External chemistry: food and smell
Our feelings are influenced not only by hormones produced by our own body, but also by some substances that we receive from the outside.
- Food as a source of neurotransmitters. Few substances in our body are synthesized from scratch. Usually complex molecules are obtained from simpler or similar ones – the so-called precursor molecules. Neurotransmitters are no exception. So, the precursor of dopamine is the amino acid tyrosine, which in turn is formed from another amino acid, phenylalanine. Phenylalanine belongs to essential amino acids: the human body is not able to synthesize it itself and can only be obtained from food. Serotonin is formed from the essential amino acid tryptophan.Tryptophan is also a precursor to melatonin. That is, without a number of amino acids entering the body from outside, neurotransmitters simply cannot appear, and the processes for which they are responsible will be disrupted.
Tip. A varied diet thus contributes to not only physical health, but also mental health. Make sure that there are enough protein-rich foods in the diet: the body “disassembles” proteins into their constituent amino acids, and already uses them for its own syntheses.
- Sugar. Ordinary sugar is a simple carbohydrate: the sucrose molecule consists of glucose and fructose and is easily broken down into them in the body. Many already know how glucose “works”: it serves as a source of energy for all processes occurring in the body, from muscle movement to the functioning of organs. Fluctuations in blood glucose levels are associated not only with physical condition, but also psychological. Firstly, hypoglycemia – low blood sugar – leads to inhibition of all energy-consuming processes, primarily muscle contractions and mental activity.There is a headache, depression. The second effect of sugar on emotions is direct: when it gets on the tongue, simple carbohydrates activate receptors that command the release of dopamine. Roughly speaking, I ate a chocolate bar – I felt joy. Unfortunately, as soon as the sweet tooth is eaten, the receptors are released and dopamine stops flowing.
Tip. It is important to maintain a stable blood glucose level. It is the sharp jumps in the level (it does not matter, up or down) that lead to mood swings.Avoid overusing simple carbohydrates or skipping meals.
- Caffeine. In addition to increased blood pressure, increased heart rate and other attributes of vigor, coffee causes mood elevation. This is also due to dopamine, but not as straightforward as with sugar. Caffeine molecules sit on a specific group of receptors and block them, and this, in turn, activates dopamine receptors – they become more susceptible to a neurotransmitter, even if there is little of it in the blood.Caffeine also has another property: it blocks the action of the enzyme phosphodiesterase, as a result of which the destruction of the secondary neurotransmitter, which helps adrenaline to act, does not occur. A secondary neurotransmitter accumulates in cells, and adrenaline, even in small amounts, works harder – coffee excites the nervous system.
Tip. Small amounts of coffee and tea tone blood vessels well and are a good way to slightly improve your mood. But don’t forget that increased consumption of caffeine can lead to sleep disturbances that can lead to prolonged stress.
- Alcohol. Ethyl alcohol has the property of accumulating in the brain: soon after consumption in the brain tissue, its content exceeds that in the blood. In low doses, alcohol activates inhibitory neurotransmitters, resulting in muscle relaxation, drowsiness, and mild euphoria. An increase in ethanol concentration leads to the release of endorphins (these are substances similar to opiates, but produced by the body itself), which, in turn, are associated with the release of dopamine.It also plays a role in generating euphoria. Finally, upon reaching a certain concentration (it is individual for each person), there is a clouding of consciousness up to hallucinations, a malfunction of the adrenaline system with subsequent unpredictable occurrences of fear and anxiety, memory impairment and a number of other negative consequences for the psyche. The constant use of alcohol leads to the death of neurons.
Tip. The Ministry of Health warns about the dangers of alcohol for a reason. However, one glass of wine occasionally will not cause irreversible consequences.Just take it responsibly.
- The role of odors. As mentioned earlier, the body “remembers” pleasant situations and reacts to their repetition with a sense of joy. The same applies to negative cases: imprinting occurs – the imprinting of the situation. With the repetition of the conditions in which a certain situation arose, the feelings associated with it are repeated – there is a joint activation of neural pathways.Smell is the most ancient sensory system, it appeared in the evolutionary path of our ancestors earlier than others, therefore the reaction to smells is the most “deep” – neural pathways-associations are firmly established. This means that, for example, the scent of mother’s perfume will always evoke childhood joy in the memory, even if you accidentally feel it while crossing the metro at rush hour. And the smell of disinfectant in the dentist’s office can lead to involuntary fear. Such reactions are always individual and associated with personal experience.
However, there are some more or less general patterns. Roughly speaking, pleasant smells evoke pleasant emotions and vice versa. This is what scent marketing is based on – a technology that allows you to attract customers to a store and encourage them to buy. This includes simply maintaining a pleasant scent in boutiques or salons, and creating a specific scent for a company – a brand’s “aromatics”, and using special scents that evoke certain emotions and desires. For example, sellers of kitchen appliances often spray the aromas of cinnamon and vanilla in the sales area – the buyer has a feeling of the coziness of home cooking and the desire to buy a new stove or oven for it.And marketing research in the US and Germany showed that in shopping malls, shoppers spent 20% more time in scented rooms.
Tip. The ubiquitous use of scent marketing does not mean that you should only go shopping with a bad cold. But understanding the background odor in such situations can help avoid impulsive waste.
Gynecologists and endocrinologists often advise patients to check their hormonal levels and sometimes correct them.What hormones are, and which ones are especially important for women’s health, we will discuss.
The work of the endocrine system (ES) is comparable to the work of a symphony orchestra of several hundred musicians, capable of performing both the most gentle quiet melody and a powerful thousand-voice symphony. It also resembles a bright fireworks display, when the sky is illuminated with a myriad of multi-colored flares and lights. ES easily and masterly controls countless hormones – soundless and fast, like flashing lights, obedient and weightless, like musical sounds.
Faithful ES agents
ES is responsible for all chemistry in the human body. This is a laboratory that produces special substances – hormones that provide a chemical balance in the body. Hormones control the work of every cell in the body. Each hormone is responsible for its own organ, but also interacts with other hormones. If the endocrine glands produce the right amount of hormones, then everything in the body is balanced and healthy. If the gland malfunctions, the work of the organ controlled by its hormones is also disrupted.The mystery of nature is still how and from what substances the endocrine glands produce hormones, and what happens to hormones when they have served their purpose.
The pituitary gland is the main endocrine gland. She directs the work of the entire ES with the help of four hormones it produces – somatotropic, gonadotropic, mammotropic, thyroid-stimulating.
Growth hormone, or growth hormone, is responsible for the growth and development of cells and the whole organism as a whole.It also manages the aging, repair and rejuvenation of cells. So a decrease in the production of growth hormone after 40 years in women by a chain reaction leads to menopause. The existence of people of dwarf and gigantic growth is also “on the conscience” of this hormone. Surprisingly, at different age periods of life, the pituitary gland produces different amounts of growth hormone: in infancy and childhood – a small amount, in adolescence – much more.
Mammotropic hormone or prolactin promotes the formation and production of milk after childbirth.
Gonadotropic hormones – hormones that stimulate the ovaries and female sex glands. There are two of them – FSH and LH, and they control the rhythmic work of the ovaries and uterus, provide the menstrual cycle. A few years before the start of the girl’s first menstruation, the pituitary gland receives instructions from the hypothalamus to produce these two hormones, preparing the launch of her reproductive system. FSH or follicle-stimulating hormone predominates in the blood during the first half of the menstrual cycle. It causes an increased secretion of estrogen by the ovaries and stimulates the maturation of follicles.LH or luteinizing hormone is the main hormone of the second phase of the cycle. As soon as one of the follicles matures, the pituitary gland releases LH into the blood, while sharply reducing the production of FSH (which in turn reduces the production of estrogen).
Thyroid stimulating hormones (TSH) control the thyroid gland and the production of thyroid hormones.
In ancient times, scientists believed that the thyroid gland in women exists to make the female neck smoother and more beautiful.As it turned out, the thyroid gland carries not only an aesthetic, but also a practical load, since its hormones are responsible for the metabolism in the body. These hormones are called thyroid hormones. There are two of them: thyroxine (T4) and triiodothyronine (T3) (More about them on page 6). In addition, thyroid hormones help growth hormone in the implementation of the growth function.
The two main ones are insulin and glucagon. They work in balance to regulate blood sugar.
Insulin reduces sugar content, affects fat metabolism.Impaired insulin secretion is the cause of diabetes mellitus. The need for insulin occurs when the glucose level in the blood rises. Insulin enters the bloodstream and, first, makes the membranes of the body’s cells more permeable to glucose. It further promotes the conversion of glucose into glycogen, which is deposited in the liver and muscles. So the blood sugar is reduced.
Glucagon, on the other hand, “extracts” glycogen from storage and increases blood sugar.
These two hormones are also involved in controlling the activity of the pancreas itself, either stimulating or blocking the synthesis of digestive enzymes.
Hormones of the upper adrenal cortex
The most famous of all is adrenaline, the first hormone that scientists have managed to study and synthesize. Adrenaline is consistently associated with stress. As soon as a threat to human health arises, the adrenal glands release adrenaline into the blood, after which the body’s defenses are mobilized (in particular, brain activity and cardiac function are activated). This endocrine organ also produces other important hormones.
Gluosteroids (cortisone, corticosterone, hydrocortisone) stimulate the absorption of carbohydrates, fats and proteins, inhibit the development of inflammatory processes.
Mineralocorticoids activate the metabolism of inorganic substances – minerals, sodium, potassium, chlorides and, in spite of the hormones of the previous group, stimulate the development of inflammatory processes.
Sex hormones (estrogens, androgens, progesterone) form the differentiation of primary sexual characteristics in the fetus even before birth.Later, they provide external attributes such as femininity and masculinity. When the ovaries stop producing female hormones in sufficient quantities, sex hormones, produced in small quantities by the adrenal glands, come to their aid. They will be needed by a woman in menopause and postmenopause as a source of strength and balance.
Androgen (male hormone), promotes the development of muscles and hair in women. in addition, it affects the strengthening of the sebaceous glands during the formation of femininity.It stimulates the appearance of pubic hair, specific female odors, balanced sweating, which is no longer typical for a child’s body, but for a woman’s. If this function is disturbed, acne and excessive hairiness appear. Androgen is also responsible for the balance in the body of female and male hormones.
They are called “guardian angels” of the attributes of femininity. The girl develops in the same way as the boy, until the ovaries begin to produce the main female hormone, estrogen.After that, the formation proceeds according to the female type.
Estrogen is a general term that groups many different substances with the same physiological action. Signs of a woman’s physical maturity, such as menstruation and pregnancy, depend on it. The quality of the skin, the size of the breasts, the distribution of hair, the growth and hardness of bones, the function of the endocrine glands and the nervous system depend on it, it affects the emotional state. Most internal organs have specific receptors for estrogen, and a decrease in estrogen production is reflected in each organ.A decrease in estrogen production leads to menopause. Estrogen is a powerful growth regulator, stopping, for example, the growth of long bones (estrogen commands the pituitary gland to reduce the secretion of growth hormone). Slowing down is one of the functions that the ovaries endow estrogen with during late childhood in girls.
As already mentioned, estrogens are also produced by the adrenal cortex, and also by the corpus luteum, which remains when the egg has left the follicle and went to meet its destiny – sperm.
Progesterone is also produced by the corpus luteum during the second period of the cycle. It stimulates the lining of the uterus (endometrium) and prepares a “home” for the fertilized egg cell.