hormone

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Endocrine glands are among the most important glands in the human body. Hormones secreted by these (credit: Encyclopædia Britannica, Inc.)

Organic compound (often a steroid or peptide) that is produced in one part of a multicellular organism and travels to another part to exert its action. Hormones regulate physiological activities including growth, reproduction, and homeostasis in vertebrates; molting and maintenance of the larval state ( larva) in insects; and growth, bud dormancy, and leaf shedding in plants. Most vertebrate hormones originate in specialized tissues ( endocrine system; gland) and are carried to their targets through the circulation. Among the many mammalian hormones are ACTH, sex hormones, thyroxine, insulin, and epinephrine. Insect hormones include ecdysone, thoracotropic hormone, and juvenile hormone. Plant hormones include ethylene, abscisin, auxins, gibberellins, and cytokinins.

For more information on hormone, visit Britannica.com.

One of the chemical messengers produced by endocrine glands, whose secretions are liberated directly into the bloodstream and transported to a distant part or parts of the body, where they exert a specific effect for the benefit of the body as a whole. The endocrine glands involved in the maintenance of normal body conditions are pituitary, thyroid, parathyroid, adrenal, pancreas, ovary, and testis. However, these organs are not the only tissues concerned in the hormonal regulation of body processes. For example, the duodenal mucosa, which is not organized as an endocrine gland, elaborates a substance called secretin which stimulates the pancreas to produce its digestive juices. The placenta is also a very important hormone-producing tissue. See separate articles on the individual glands.

The hormones obtained from extracts of the endocrine glands may be classified into four groups according to their chemical constitution: (1) phenol derivatives, such as epinephrine, norepinephrine, thyroxine, and triiodothyronine; (2) proteins, such as the anterior pituitary hormones, with the exception of adrenocorticotropic hormone (ACTH), human chorionic gonadotropin, pregnant-mare-serum gonadotropin, and thyroglobulin; (3) peptides, such as insulin, glucagon, ACTH, vasopressin, oxytocin, and secretin; and (4) steroids, such as estrogens, androgens, progesterone, and corticoids. Hormones, with a few exceptions like pituitary growth hormone and insulin, may also be classified as either tropic hormones or target-organ hormones. The former work indirectly through the organs or glands which they stimulate, whereas the latter exert a direct effect on peripheral tissues. See also Endocrine system (vertebrate).

Compounds produced in the body in endocrine glands, and released into the bloodstream, where they act as chemical messengers to affect other tissues and organs.

A chemical produced in one part of the body (an endocrine gland), which has its effects in another part (the target structures). Hormones are chemical messengers transported in the bloodstream; they regulate and coordinate the activity of many organs in the body.

Despite the advent of e-mail the majority of people still communicate by letter or telephone. Similarly there are two ways in which messages are sent round the body. The first is via the nervous system, which like the phone system is ‘hard wired’ and usually operates on a point to point basis. The second way is by means of hormones — chemical messengers — circulating in the blood, which effectively acts as a postal system. Just as, when someone sends out a circular in the mail, those who are interested act on the information and those who are not discard the letter, so when an endocrine gland secretes a hormone the appropriate cells respond while the rest are unaffected. Classically, hormones are defined as chemical substances secreted directly into the bloodstream that act on a distant target organ or type of cell.

Historical background

Diseases resulting from lack of a hormone (such as diabetes mellitus), or excess production (such as thyrotoxicosis), have been known for centuries, although the cause was not recognized. A nineteenth-century anatomist called Henle, after whom a section of the renal tubules was named, was the first person to describe glands without ducts that secreted their products directly into the bloodstream. Then in 1855 the Frenchman, Claude Bernard, who laid the foundations of physiology, distinguished the products of these so-called ductless glands from those glandular secretions, such as saliva and sweat, which are effectively outside the body, by calling them ‘internal secretions’: hence the name ‘endocrine’ (endon: Greek for within) as opposed to ‘exocrine’ secretion (ex: Greek for outside).

The first person who tried to use extracts of endocrine glands for therapeutic purposes was Brown-Sequard, a French physician, neurologist, and endocrinologist, who in 1889 employed testicular extracts from animals to treat male ageing. A few years later, in 1902, Bayliss and Starling, working in University College London, prepared an extract from the duodenum which stimulated secretion of pancreatic digestive juices when it was injected into the bloodstream. They called the product ‘secretin’, and coined the term ‘hormone’, meaning ‘to excite’ or ‘to set in motion’. Since then a wide variety of hormones have been identified. The steps in identifying whether a given gland or tissue has an endocrine function are first to demonstrate changes on its removal and then to demonstrate reversal of those changes, either when the gland is reimplanted at any site where it can link up with a blood supply, or when an extract of the gland is injected into the blood. The active principle can then be isolated, purified, and the chemical structure characterized. Ways of measuring the identified hormone (assays) can be established, and finally one can confirm that venous blood leaving the gland has a higher concentration of the hormone than the arterial blood entering it.

The role of hormones

The major endocrine glands are the pituitary, the thyroid, the four parathyroids, the pancreas, the two adrenals, and the paired testes or ovaries (See endocrine). Hormones are also produced by organs or tissues whose function is not primarily an endocrine one: the digestive tract, the heart, and the kidneys all produce hormones. Even nerve cells produce them. For example, the hormones controlling secretion from the anterior lobe of the pituitary gland are synthesized in the hypothalamus, but they are released into the local blood supply to the anterior pituitary, rather than entering the general circulation. These cells are said to have a neuroendocrine function. Furthermore, it is now recognized that hormones need not even be released into blood vessels. The hormonal products of some nerve cells stimulate adjacent neurones and thus act as neuromodulators, while in the digestive tract hormones act on surrounding cells and are said to have a paracrine function (para: Greek for beside). Finally, some hormones, such as growth factors, can act on the originating cell itself; in this case they are described as exhibiting autocrine control. The classical definition has therefore been extended to include chemical messengers which are secreted by certain cells, and which reach and act upon cells which are receptive to them, whether local or distant.

Chemical nature of hormones

Chemically, most hormones belong to one of three major groups: proteins and peptides, steroids (fat-soluble molecules whose basic structure is a skeleton of four carbon rings), or derivatives of the amino acid tyrosine, characterized by a 6-carbon, or benzene, ring. There are some hormones, such as melatonin from the pineal gland and the locally acting prostaglandins, which cannot be included in any of these groups, but may share a number of their characteristics. The glands which produce protein and peptide hormones are the pituitary, certain cells of the thyroid, the parathyroids, and the pancreas. Steroids are produced by the cortex or outer layer of the adrenal gland and by the ovaries and testes. The tyrosine derivatives are the thyroid hormones, and the catecholamines (adrenaline and noradrenaline) which are produced in the medulla of the adrenal glands.

Knowledge of the chemical nature of a hormone is important as it enables one to predict how the hormone is produced, how rapidly it can be released in response to a stimulus, in what form it circulates in the blood, how it acts, the time course of its effect, and the route of administration therapeutically.

Hormone synthesis and secretion

The mechanisms underlying the synthesis of protein and peptide hormones, such as growth hormone and insulin, are just the same as the synthesis of any other protein, involving transcription of the gene and translation of a messenger RNA (mRNA). Generally the mRNA contains the code for a longer peptide than the normal form of the hormone. These extended forms are called pro-hormones and there may even be pre-pro-hormones, as for example pre-pro-insulin. The active hormone is cleaved from these molecules. The pro-hormone is stored in secretory granules, then released by a process of exocytosis, — the membrane of the storage granule fuses with the plasma membrane, which in turn parts, allowing the contents of the granule to be discharged.

Steroid hormones, such as cortisol and the sex hormones, are all synthesized from cholesterol, with a variety of enzymes mediating the transformations into the different products. Since they are fat soluble, and therefore readily cross membranes, they cannot be stored, but are synthesized as needed. Their release is therefore slower than that of peptide hormones.

The thyroid hormones are formed as part of a large protein, thyroglobulin, which can be stored, while the catecholamines are synthesized by a multi-enzyme process and are also stored in granules.

Neither the steroid hormones nor the thyroid hormones are readily soluble in water, and they circulate in the plasma in association with proteins. The importance of this is that the compound molecules are too large to be filtered out of the blood in the kidney and so are not lost in the urine, which is one of the reasons why they remain in the plasma for days. Peptide hormones, by contrast, disappear within an hour or so, because they are both broken down in plasma and tissues and also lost in the urine. Protein and peptide hormones have therefore to be administered more frequently if used therapeutically, although longer acting preparations are available. Another problem with the administration of these hormones is the fact that they cannot be given by mouth as they would be broken down in the digestive tract. This presents particular problems for diabetics, who have regularly to inject themselves, whereas people with thyroid hormone deficiency only have to take pills.

Hormone action

The chemical nature of the hormone also affects the mechanism of action. All hormones act on cells by way of their ‘receptors’. Each hormone has its own receptor to which it binds, matching rather like a lock and key. This is why hormones circulating throughout the body in the blood may leave capillaries to enter the extracellular fluid of many tissues, but act only on those cells which possess the appropriate receptor. Proteins and peptides cannot enter the cell and so act via cell membrane receptors, producing their effects by ‘second messengers’, which are activated in the cell as soon as the hormone binds to the receptor. Thus peptide hormones can produce quite rapid responses. Steroid and thyroid hormones, by contrast, can enter the cell and bind to intracellular receptors, producing their effects by stimulating the production of new proteins. There is therefore a relatively long lag period before the response to these hormones is seen.

Hormones produce a variety of responses throughout the body and may be grouped according to their actions, although there is overlap between the groups.

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Regulation of hormone release

The commonest form of control in biological systems is negative feedback, and this forms the basis for the control of hormone release. In this type of feedback loop any perturbation of the controlled variable results in a response to return it to the pre-determined level. An example of this is the control of blood sugar concentrations. A rise in blood glucose (after a sugary drink or food) acts on the pancreas to stimulate insulin secretion, which in turn lowers blood glucose by storing it away inside cells.

A more complex system is seen in the control of pituitary hormone secretion. For hormones which control secretion from a target gland, there is simple negative feedback, with the target organ secretion inhibiting pituitary hormone release (for example, the secretion of thyroid-stimulating hormone is inhibited by a rise in circulating thyroid hormone). However there is also control from the hypothalamus via stimulating and inhibiting hormones. The hypothalamus receives a huge array of inputs originating both in the body and in the external environment, so that by this route a large variety of factors influence the output of the pituitary gland, and hence the other endocrine glands, which it in turn controls.

Endocrine disorders

In a such a complex regulatory system, one would predict that disordered function would have significant consequences. The most common endocrine disorder is diabetes mellitus, with disorders of thyroid function coming second. Endocrine disorders may stem from over- or undersecretion of a given hormone. Oversecretion may be due to a tumour either in the tissue normally producing the hormone or in one growing in an abnormal location — for example in the lung. It may alternatively be due to inappropriate secretion from the whole gland. There is, for example, an autoimmune disease of the thyroid: thyrotoxicosis or ‘Grave's disease’, in which antibodies stimulate the gland to oversecretion. Apparent underactivity of an endocrine gland may in fact be due to a failure of the target tissues to respond to a particular hormone. For example, those who develop diabetes later in life may have an elevated rather than a low concentration of insulin in the blood. This is because their tissues are relatively unresponsive to the hormone. There may even be failure to convert a hormone to its more active form. In the male some tissues are responsive to dihydrotestosterone rather than testosterone itself, and so a deficiency of the enzyme catalyzing this conversion produces the appearance of testosterone deficiency.

Most endocrine disorders can now be successfully treated. Diagnosis and treatment, however, require accurate measurement of blood hormone concentrations. Early assays were bioassays performed on animal tissue, and these are still used in checking the activity of hormone preparations made for medicinal purposes. However, routine determination in blood now involves the technique of radioimmunoassay; when care is taken in setting this up, even very low concentrations of hormone can be determined quite rapidly on a large number of samples.

So the days are past when diabetes mellitus led inexorably to coma and death; when a mother might decline with a mysterious illness after giving birth because of post-partum pituitary degeneration; or when a young woman could ‘burn out’ with thyrotoxicosis — to name but a few of the endocrine disorders which could be seriously debilitating or fatal before the twentieth century.

— Mary L. Forsling

Bibliography

• Rubenstein, E. (1980). Diseases caused by impaired communication among cells, Scientific American, March, 78-87.
• Snyder, S. H. (1985). The molecular basis of communication between cells, Scientific American, October, 114-23

See endocrine. See also adrenal gland; glands; hypothalamus; insulin; peptides; pituitary gland; sex hormones; steroids; thyroid gland; water balance.

A chemical produced in one part of the body, which has its effects on another part (target cells). Endocrine glands are the sites of secretion. The bloodstream transports the hormones to their target tissues. Hormones act as chemical messengers. helping to regulate specific body functions.

Chemical substances, produced in the body by endocrine glands, that are transported by the blood to other organs to stimulate their function. Adrenaline, estrogen, insulin, and testosterone are all hormones.

Emanating from or pertaining to hormones.

• h. antibodies — hormones can be used as antigens and antibodies produced against them so that reproductive functions can be retarded or enhanced.
• h. dermatoses — skin diseases caused by an abnormality of any of the many hormones that influence the skin and adnexa, particularly growth of hair. See also endocrine alopecia.
• h. hypersensitivity — a papulocrustous dermatitis associated with hypersensitivity to endogenous gonadal hormones. Seen most commonly in bitches during stages of the estrus cycle.
• h. pregnancy diagnosis — performed commercially in cows by determining that progesterone levels in milk are maintained after mating instead of declining by the 20th day.
• h. synergism — when their combined effect is greater than the simple addition of each of their individual effects.

The biochemical secretions of the endocrine glands that, in relatively small quantities, partially regulate the physiologic activity of the tissues, organs, organ systems, and other endocrine glands, and of the nervous system itself. The hormonal secretions are conducted and distributed throughout the body by the circulation of the bloodstream and tissue fluids.

• Endocrine System and Glands - hormone: organic substance, such as insulin, prolactin, adrenalin, estrogen, or testosterone, produced by endocrine glands and carried by bloodstream to produce a metabolic effect
• Physiology - hormone: chemical agent usu. released by ductless gland that has regulatory effect on functions in other parts of body
• PHARMACOLOGY - hormone: substance produced by endocrine gland that travels to another body site where it alters structure or function
• Mental States, Processes, and Behavior - hormone: any of various chemicals secreted by glands that affect behavior

For other uses, see Hormone (disambiguation).

Epinephrine (adrenaline), a catecholamine-type hormone

A hormone (from Greek ὁρμή, "impetus") is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one cell to another.^[1] All multicellular organisms produce hormones; plant hormones are also called phytohormones. Hormones in animals are often transported in the blood. Cells respond to a hormone when they express a specific receptor for that hormone. The hormone binds to the receptor protein, resulting in the activation of a signal transduction mechanism that ultimately leads to cell type-specific responses.

Endocrine hormone molecules are secreted (released) directly into the bloodstream, whereas exocrine hormones (or ectohormones) are secreted directly into a duct, and, from the duct, they flow either into the bloodstream or from cell to cell by diffusion in a process known as paracrine signalling.

Recently it has been found that a variety of exogenous modern chemical compounds have hormone-like effects on both humans and wildlife. Their interference with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body can change the homeostasis, reproduction, development, and/or behavior, just as endogenously produced hormones do."^[2]

Contents 1 Hormones as signals 2 Interactions with receptors 3 Physiology of hormones 4 Effects of hormones 5 Chemical classes of hormones 6 Pharmacology 7 Important human hormones 8 See also 9 References 10 External links

Hormones as signals

Hormonal signaling involves the following:^{[citation needed]}

1. Biosynthesis of a particular hormone in a particular tissue
2. Storage and secretion of the hormone
3. Transport of the hormone to the target cell(s)
4. Recognition of the hormone by an associated cell membrane or intracellular receptor protein
5. Relay and amplification of the received hormonal signal via a signal transduction process: This then leads to a cellular response. The reaction of the target cells may then be recognized by the original hormone-producing cells, leading to a down-regulation in hormone production. This is an example of a homeostatic negative feedback loop.
6. Degradation of the hormone.

Hormone cells are typically of a specialized cell type, residing within a particular endocrine gland, such as thyroid gland, ovaries, and testes. Hormones exit their cell of origin via exocytosis or another means of membrane transport. The hierarchical model is an oversimplification of the hormonal signaling process. Cellular recipients of a particular hormonal signal may be one of several cell types that reside within a number of different tissues, as is the case for insulin, which triggers a diverse range of systemic physiological effects. Different tissue types may also respond differently to the same hormonal signal. Because of this, hormonal signaling is elaborate and hard to dissect.^{[citation needed]}

Interactions with receptors

Most hormones initiate a cellular response by initially combining with either a specific intracellular or cell membrane associated receptor protein. A cell may have several different receptors that recognize the same hormone and activate different signal transduction pathways, or a cell may have several different receptors that recognize different hormones and activate the same biochemical pathway.

For many hormones, including most protein hormones, the receptor is membrane-associated and embedded in the plasma membrane at the surface of the cell. The interaction of hormone and receptor typically triggers a cascade of secondary effects within the cytoplasm of the cell, often involving phosphorylation or dephosphorylation of various other cytoplasmic proteins, changes in ion channel permeability, or increased concentrations of intracellular molecules that may act as secondary messengers (e.g., cyclic AMP). Some protein hormones also interact with intracellular receptors located in the cytoplasm or nucleus by an intracrine mechanism.

For hormones such as steroid or thyroid hormones, their receptors are located intracellularly within the cytoplasm of their target cell. To bind their receptors, these hormones must cross the cell membrane. They can do so because they are lipid-soluble. The combined hormone-receptor complex then moves across the nuclear membrane into the nucleus of the cell, where it binds to specific DNA sequences, effectively amplifying or suppressing the action of certain genes, and affecting protein synthesis.^[3] However, it has been shown that not all steroid receptors are located intracellularly. Some are associated with the plasma membrane.^[4]

An important consideration, dictating the level at which cellular signal transduction pathways are activated in response to a hormonal signal, is the effective concentration of hormone-receptor complexes that are formed. Hormone-receptor complex concentrations are effectively determined by three factors:

1. The number of hormone molecules available for complex formation
2. The number of receptor molecules available for complex formation
3. The binding affinity between hormone and receptor.

The number of hormone molecules available for complex formation is usually the key factor in determining the level at which signal transduction pathways are activated, the number of hormone molecules available being determined by the concentration of circulating hormone, which is in turn influenced by the level and rate at which they are secreted by biosynthetic cells. The number of receptors at the cell surface of the receiving cell can also be varied, as can the affinity between the hormone and its receptor.

Physiology of hormones

Most cells are capable of producing one or more molecules, which act as signaling molecules to other cells, altering their growth, function, or metabolism. The classical hormones produced by cells in the endocrine glands mentioned so far in this article are cellular products, specialized to serve as regulators at the overall organism level. However, they may also exert their effects solely within the tissue in which they are produced and originally released.

The rate of hormone biosynthesis and secretion is often regulated by a homeostatic negative feedback control mechanism. Such a mechanism depends on factors that influence the metabolism and excretion of hormones. Thus, higher hormone concentration alone cannot trigger the negative feedback mechanism. Negative feedback must be triggered by overproduction of an "effect" of the hormone.

Hormone secretion can be stimulated and inhibited by:

• Other hormones (stimulating- or releasing -hormones)
• Plasma concentrations of ions or nutrients, as well as binding globulins
• Neurons and mental activity
• Environmental changes, e.g., of light or temperature

One special group of hormones is the tropic hormones that stimulate the hormone production of other endocrine glands. For example, thyroid-stimulating hormone (TSH) causes growth and increased activity of another endocrine gland, the thyroid, which increases output of thyroid hormones.

A recently identified class of hormones is that of the "hunger hormones" - ghrelin, orexin, and PYY 3-36 - and "satiety hormones" - e.g., cholecystokinin, leptin, nesfatin-1, obestatin.

To release active hormones quickly into the circulation, hormone biosynthetic cells may produce and store biologically inactive hormones in the form of pre- or prohormones. These can then be quickly converted into their active hormone form in response to a particular stimulus.

Effects of hormones

Hormones have the following effects on the body:

• stimulation or inhibition of growth
• mood swings
• induction or suppression of apoptosis (programmed cell death)
• activation or inhibition of the immune system
• regulation of metabolism
• preparation of the body for mating, fighting, fleeing, and other activity
• preparation of the body for a new phase of life, such as puberty, parenting, and menopause
• control of the reproductive cycle
• hunger cravings
• sexual arousal

A hormone may also regulate the production and release of other hormones. Hormone signals control the internal environment of the body through homeostasis.

Chemical classes of hormones

Vertebrate hormones fall into three chemical classes:

• Peptide hormones consist of chains of amino acids. Examples of small peptide hormones are TRH and vasopressin. Peptides composed of scores or hundreds of amino acids are referred to as proteins. Examples of protein hormones include insulin and growth hormone. More complex protein hormones bear carbohydrate side-chains and are called glycoprotein hormones. Luteinizing hormone, follicle-stimulating hormone and thyroid-stimulating hormone are glycoprotein hormones. There is also another type of hydrophilic hormone called nonpeptide hormones. Although they don't have peptide connections, they are assimilated as peptide hormones.
• Lipid and phospholipid-derived hormones derive from lipids such as linoleic acid and arachidonic acid and phospholipids. The main classes are the steroid hormones that derive from cholesterol and the eicosanoids. Examples of steroid hormones are testosterone and cortisol. Sterol hormones such as calcitriol are a homologous system. The adrenal cortex and the gonads are primary sources of steroid hormones. Examples of eicosanoids are the widely studied prostaglandins.
• Monoamines derived from aromatic amino acids like phenylalanine, tyrosine, tryptophan by the action of aromatic amino acid decarboxylase enzymes.

Pharmacology

Many hormones and their analogues are used as medication. The most commonly prescribed hormones are estrogens and progestagens (as methods of hormonal contraception and as HRT), thyroxine (as levothyroxine, for hypothyroidism) and steroids (for autoimmune diseases and several respiratory disorders). Insulin is used by many diabetics. Local preparations for use in otolaryngology often contain pharmacologic equivalents of adrenaline, while steroid and vitamin D creams are used extensively in dermatological practice.

A "pharmacologic dose" of a hormone is a medical usage referring to an amount of a hormone far greater than naturally occurs in a healthy body. The effects of pharmacologic doses of hormones may be different from responses to naturally occurring amounts and may be therapeutically useful. An example is the ability of pharmacologic doses of glucocorticoid to suppress inflammation.

Important human hormones

See: List of human hormones

See also

• Endocrinology
• Endocrine system
• Neuroendocrinology
• Plant hormones or plant growth regulators
• Autocrine signaling
• Paracrine signaling
• Intracrine
• Cytokine
• Growth factor
• Hormone disruptor
• Sexual motivation and hormones

References

1. ^ "Hormones". http://www.nlm.nih.gov/medlineplus/hormones.html. 
2. ^ Crisp TM, Clegg ED, Cooper RL, Wood WP, Anderson DG, Baetcke KP, Hoffmann JL, Morrow MS, Rodier DJ, Schaeffer JE, Touart LW, Zeeman MG, Patel YM (1998). "Environmental endocrine disruption: An effects assessment and analysis". Environ. Health Perspect. 106 (Suppl 1): 11–56. PMC 1533291. PMID 9539004. //www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1533291. 
3. ^ Beato M, Chavez S and Truss M (1996). "Transcriptional regulation by steroid hormones". Steroids 61 (4): 240–251. doi:10.1016/0039-128X(96)00030-X. PMID 8733009. 
4. ^ Hammes SR (2003). "The further redefining of steroid-mediated signaling". Proc Natl Acad Sci USA 100 (5): 21680–2170. doi:10.1073/pnas.0530224100. PMC 151311. PMID 12606724. //www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=151311. 

External links

• The Hormone Foundation
• Article on hormones and their receptors
• HMRbase: A database of hormones and their receptors
• MeSH Hormones

v t e Endocrine system: hormones (Peptide hormones · Steroid hormones) Endocrine glands Hypothalamic- pituitary Hypothalamus GnRH · TRH · Dopamine · CRH · GHRH/Somatostatin  · Melanin concentrating hormone Posterior pituitary Vasopressin · Oxytocin Anterior pituitary α (FSH FSHB, LH LHB, TSH TSHB, CGA) · Prolactin · POMC (CLIP, ACTH, MSH, Endorphins, Lipotropin) · GH Adrenal axis Adrenal cortex: aldosterone · cortisol · DHEA Adrenal medulla: epinephrine · norepinephrine Thyroid axis Thyroid: thyroid hormone (T3 and T4) · calcitonin Parathyroid: PTH Gonadal axis Testis: testosterone · AMH · inhibin Ovary: estradiol · progesterone · activin and inhibin · relaxin (pregnancy) Placenta: hCG · HPL · estrogen · progesterone Islet-Acinar Axis Pancreas: glucagon · insulin · amylin · somatostatin · pancreatic polypeptide Pineal gland Pineal gland: melatonin Non-end. glands Thymus: Thymosin (Thymosin α1, Thymosin beta) · Thymopoietin · Thymulin Digestive system: Stomach: gastrin · ghrelin · Duodenum: CCK · Incretins (GIP, GLP-1)  · secretin · motilin · VIP · Ileum: enteroglucagon · peptide YY · Liver/other: Insulin-like growth factor (IGF-1, IGF-2) Adipose tissue: leptin · adiponectin · resistin Skeleton: Osteocalcin Kidney: JGA (renin) · peritubular cells (EPO) · calcitriol · prostaglandin Heart: Natriuretic peptide (ANP, BNP) M: END anat/phys/devp/horm noco(d)/cong/tumr, sysi/epon proc, drug (A10/H1/H2/H3/H5)

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Dansk (Danish)
n. - hormon, hormonpræparat

idioms:

• hormone replacement therapy    hormontilskud

Nederlands (Dutch)
hormoon

Français (French)
n. - hormone

idioms:

• hormone replacement therapy    hormonothérapie substitutive

Deutsch (German)
n. - Hormon

idioms:

• hormone replacement therapy    Behandlung mit Östrogen, um die Menopause-Symptome abzuschwächen

Ελληνική (Greek)
n. - (βιολ., μτφ.) ορμόνη

idioms:

• hormone replacement therapy    θεραπεία αναπλήρωσης ορμονών

Italiano (Italian)
ormone

idioms:

• hormone replacement therapy    terapia ormonale

Português (Portuguese)
n. - hormônio (m) (Med.)

idioms:

• hormone replacement therapy    hormonoterapia (f) substitutiva (Med.)

Русский (Russian)
гормон

idioms:

• hormone replacement therapy    гормоно-заместительная терапия

Español (Spanish)
n. - hormona

idioms:

• hormone replacement therapy    hormonoterapia

Svenska (Swedish)
n. - hormon

中文（简体）(Chinese (Simplified))
荷尔蒙, 激素

idioms:

• hormone replacement therapy    更换荷尔蒙治疗法

中文（繁體）(Chinese (Traditional))
n. - 荷爾蒙, 激素

idioms:

• hormone replacement therapy    更換荷爾蒙治療法

한국어 (Korean)
n. - 호르몬

日本語 (Japanese)
n. - ホルモン

idioms:

• hormone replacement therapy    ホルモン置き換え治療

العربيه (Arabic)
‏(الاسم) الهرمون, مادة تفرزها بعض الغدد الصم قتزيد من نشاط الاعضاء التي تستقبلها عن طريق الدم, مادة صنعيه تعمل عمل الهرمون‏

עברית (Hebrew)
n. - ‮חומר המיוצרבגוף ומועבר לנוזלי הרקמות כדי להמריץ תאים או רקמות לפעולה, הורמון, חומר מלאכותי המשפיע כהורמון‬

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