Array ( [0] => {{Short description|Biological signalling molecule}} [1] => {{cs1 config|name-list-style=vanc}} [2] => {{Other uses}} [3] => [[File:Hormone Transport.png|thumb|283x283px|Left: A hormone feedback loop in a female adult. (1) [[follicle-stimulating hormone]], (2) [[luteinizing hormone]], (3) [[progesterone]], (4) [[estradiol]]. Right: [[auxin]] transport from leaves to roots in [[Arabidopsis thaliana|''Arabidopsis thaliana'']]]] [4] => A '''hormone''' (from the [[Ancient Greek|Greek]] participle {{lang|grc|ὁρμῶν}}, "setting in motion") is a class of [[cell signaling|signaling molecules]] in [[multicellular organism]]s that are sent to distant organs or tissues by complex biological processes to regulate [[physiology]] and [[behavior]].{{Cite book|title=Biology for a Changing World, with Physiology| vauthors = Shuster M |isbn= 978-1-4641-5113-2 |edition=Second|location=New York, NY | publisher = W. H. Freeman |oclc=884499940|date = 2014-03-14}} Hormones are required for the correct development of [[animal]]s, [[plant]]s and [[fungi]]. Due to the broad definition of a hormone (as a signaling molecule that exerts its effects far from its site of production), numerous kinds of molecules can be classified as hormones. Among the substances that can be considered hormones, are [[eicosanoid]]s (e.g. [[prostaglandin]]s and [[thromboxane]]s), [[steroid]]s (e.g. [[Estrogen|oestrogen]] and [[brassinosteroid]]), [[amino acid]] derivatives (e.g. [[epinephrine]] and [[auxin]]), [[protein]] or [[peptide]]s (e.g. [[insulin]] and [[CLE peptide]]s), and [[gas]]es (e.g. [[ethylene]] and [[nitric oxide]]). [5] => [6] => Hormones are used to communicate between [[organ (anatomy)|organs]] and [[Tissue (biology)|tissues]]. In [[vertebrate]]s, hormones are responsible for regulating a wide range of processes including both [[physiological]] processes and [[behavioral]] activities such as [[digestion]], [[metabolism]], [[respiration (physiology)|respiration]], [[sensory perception]], [[sleep]], [[excretion]], [[lactation]], [[stress (physiology)|stress]] induction, [[human development (biology)|growth and development]], [[motor coordination|movement]], [[reproduction]], and [[mood (psychology)|mood]] manipulation.{{cite book | vauthors = Neave N | title= Hormones and behaviour: a psychological approach | year= 2008 | publisher= Cambridge Univ. Press | location= Cambridge | isbn= 978-0-521-69201-4}}{{cite journal | title= Hormones and Behaviour: A Psychological Approach (review) | journal=Perspectives in Biology and Medicine | publisher=Project Muse | volume=53 | issue=1 | year=2010 | issn=1529-8795 | doi=10.1353/pbm.0.0141 | pages=152–155 | vauthors = Gibson CL | s2cid=72100830 }}{{cite web | title= Hormones | url= https://medlineplus.gov/hormones.html | work= MedlinePlus | publisher= U.S. National Library of Medicine}} In plants, hormones modulate almost all aspects of development, from [[germination]] to [[senescence]].{{Cite web|title=Hormone - The hormones of plants|url=https://www.britannica.com/science/hormone|access-date=2021-01-05|website=Encyclopedia Britannica|language=en}} [7] => [8] => Hormones affect distant cells by binding to specific [[receptor (biochemistry)|receptor]] proteins in the target cell, resulting in a change in cell function. When a hormone binds to the receptor, it results in the activation of a [[signal transduction]] pathway that typically activates gene [[transcription (genetics)|transcription]], resulting in increased [[gene expression|expression]] of target [[protein]]s. Hormones can also act in non-genomic pathways that synergize with genomic effects.{{cite journal | vauthors = Ruhs S, Nolze A, Hübschmann R, Grossmann C | title = 30 Years of the Mineralocorticoid Receptor: Nongenomic effects via the mineralocorticoid receptor | journal = The Journal of Endocrinology | volume = 234 | issue = 1 | pages = T107–T124 | date = July 2017 | pmid = 28348113 | doi = 10.1530/JOE-16-0659 | doi-access = free }} Water-soluble hormones (such as peptides and amines) generally act on the surface of target cells via [[second messenger system|second messengers]]. Lipid soluble hormones, (such as [[steroid]]s) generally pass through the plasma membranes of target cells (both [[cell membrane|cytoplasmic]] and [[nuclear membrane|nuclear]]) to act within their [[cell nucleus|nuclei]]. Brassinosteroids, a type of polyhydroxysteroids, are a sixth class of plant hormones and may be useful as an anticancer drug for endocrine-responsive tumors to cause [[apoptosis]] and limit plant growth. Despite being lipid soluble, they nevertheless attach to their receptor at the cell surface.{{cite journal | vauthors = Wang ZY, Seto H, Fujioka S, Yoshida S, Chory J | title = BRI1 is a critical component of a plasma-membrane receptor for plant steroids | journal = Nature | volume = 410 | issue = 6826 | pages = 380–3 | date = March 2001 | pmid = 11268216 | doi = 10.1038/35066597 | bibcode = 2001Natur.410..380W | s2cid = 4412000 }} [9] => [10] => In vertebrates, [[endocrine gland]]s are specialized organs that [[Secretion|secrete]] hormones into the [[endocrine system|endocrine signaling system]]. Hormone secretion occurs in response to specific biochemical signals and is often subject to [[Negative feedback|negative feedback regulation]]. For instance, high [[blood sugar]] (serum glucose concentration) promotes [[insulin]] synthesis. Insulin then acts to reduce glucose levels and maintain [[homeostasis]], leading to reduced insulin levels. Upon secretion, water-soluble hormones are readily transported through the circulatory system. Lipid-soluble hormones must bond to [[carrier plasma glycoprotein]]s (e.g., [[thyroxine-binding globulin]] (TBG)) to form [[ligand (biochemistry)|ligand]]-protein complexes. Some hormones, such as insulin and growth hormones, can be released into the bloodstream already fully active. Other hormones, called [[prohormone]]s, must be activated in certain cells through a series of steps that are usually tightly controlled.{{Cite book| vauthors = Miller BF, Keane CB |url=https://www.worldcat.org/oclc/36465055|title=Miller-Keane Encyclopedia & dictionary of medicine, nursing & allied health.|date=1997|publisher=Saunders |isbn=0-7216-6278-1|edition=6th|location=Philadelphia|oclc=36465055}} The [[endocrine system]] [[secrete]]s hormones directly into the [[circulatory system|bloodstream]], typically via [[capillary#Types|fenestrated capillaries]], whereas the [[exocrine system]] secretes its hormones indirectly using [[duct (anatomy)|ducts]]. Hormones with [[paracrine]] function diffuse through the [[interstitial fluid|interstitial space]]s to nearby target tissue. [11] => [12] => Plants lack specialized organs for the secretion of hormones, although there is spatial distribution of hormone production. For example, the hormone auxin is produced mainly at the tips of young [[Leaf|leaves]] and in the [[Meristem|shoot apical meristem]]. The lack of specialised glands means that the main site of hormone production can change throughout the life of a plant, and the site of production is dependent on the plant's age and environment.{{Cite web|title=Plant Hormones/Nutrition|url=https://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPLANTHORM.html#:~:text=They%20are%20produced%20in%20the,lighter%20side%20of%20the%20plant.|access-date=2021-01-07|website=www2.estrellamountain.edu|archive-date=2021-01-09|archive-url=https://web.archive.org/web/20210109180441/https://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPLANTHORM.html#:~:text=They%20are%20produced%20in%20the,lighter%20side%20of%20the%20plant.|url-status=dead}} [13] => [14] => ==Introduction and overview== [15] => {{Further|Signal transduction}} [16] => [17] => Hormone producing cells are found in the [[endocrine system|endocrine glands]], such as the [[thyroid gland]], [[ovary|ovaries]], and [[testes]].{{Cite web| vauthors = Wisse B |date= 13 June 2021 |title=Endocrine glands|url=https://medlineplus.gov/ency/imagepages/1093.htm |access-date=November 18, 2021|work = MedlinePlus | publisher = U.S. National Library of Medicine }} Hormonal signaling involves the following steps:{{cite book|vauthors=Nussey S, Whitehead S |title=Endocrinology: an integrated approach|year= 2001 |publisher= Bios Scientific Publ. |location= Oxford |pmid=20821847 |isbn= 978-1-85996-252-7 |url= https://www.ncbi.nlm.nih.gov/books/NBK22/}} [18] => # '''[[Biosynthesis]]''' of a particular hormone in a particular tissue. [19] => # '''Storage and [[cellular secretion|secretion]]''' of the hormone. [20] => # '''Transport''' of the hormone to the target cell(s). [21] => # '''Recognition''' of the hormone by an [[membrane protein|associated cell membrane]] or [[intracellular]] [[receptor (biochemistry)|receptor]] protein. [22] => # '''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 [[downregulation]] in hormone production. This is an example of a [[homeostasis|homeostatic]] [[negative feedback loop]]. [23] => # '''Breakdown''' of the hormone. [24] => [25] => [[Exocytosis]] and other methods of [[cell membrane|membrane transport]] are used to secrete hormones when the endocrine glands are signaled. 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.{{citation needed|date=May 2022}} [26] => [27] => ==Discovery== [28] => ===Arnold Adolph Berthold (1849)=== [29] => [30] => [[Arnold Adolph Berthold]] was a German [[physiology|physiologist]] and [[zoology|zoologist]], who, in 1849, had a question about the function of the [[testicle|testes]]. He noticed in castrated roosters that they did not have the same sexual behaviors as [[rooster]]s with their testes intact. He decided to run an experiment on male roosters to examine this phenomenon. He kept a group of roosters with their testes intact, and saw that they had normal sized wattles and combs (secondary [[sex organ|sexual organs]]), a normal crow, and normal sexual and aggressive behaviors. He also had a group with their testes surgically removed, and noticed that their secondary sexual organs were decreased in size, had a weak crow, did not have sexual attraction towards females, and were not aggressive. He realized that this organ was essential for these behaviors, but he did not know how. To test this further, he removed one testis and placed it in the abdominal cavity. The roosters acted and had normal physical [[anatomy]]. He was able to see that location of the testes does not matter. He then wanted to see if it was a [[genetics|genetic]] factor that was involved in the testes that provided these functions. He transplanted a testis from another rooster to a rooster with one testis removed, and saw that they had normal behavior and physical anatomy as well. Berthold determined that the location or genetic factors of the testes do not matter in relation to sexual organs and behaviors, but that some [[chemical]] in the testes being secreted is causing this phenomenon. It was later identified that this factor was the hormone [[testosterone]].{{cite book |title=Principles of Endocrinology and Hormone Action | vauthors = Belfiore A, LeRoith PE |isbn=978-3-319-44675-2|location=Cham | publisher = Springer |oclc=1021173479|date=2018}}{{cite book |title=Endocrine Physiology| veditors = Molina PE |date= 2018|publisher= McGraw-Hill Education |isbn=978-1-260-01935-3 |oclc=1034587285}} [31] => [32] => === Charles and Francis Darwin (1880) === [33] => Although known primarily for his work on the [[Evolution|Theory of Evolution]], [[Charles Darwin]] was also keenly interested in plants. Through the 1870s, he and his son [[Francis Darwin|Francis]] studied the movement of plants towards light. They were able to show that light is perceived at the tip of a young stem (the [[coleoptile]]), whereas the bending occurs lower down the stem. They proposed that a 'transmissible substance' communicated the direction of light from the tip down to the stem. The idea of a 'transmissible substance' was initially dismissed by other plant biologists, but their work later led to the discovery of the first plant hormone.{{cite journal | vauthors = Whippo CW, Hangarter RP | title = Phototropism: bending towards enlightenment | journal = The Plant Cell | volume = 18 | issue = 5 | pages = 1110–9 | date = May 2006 | pmid = 16670442 | doi = 10.1105/tpc.105.039669 | pmc = 1456868 | doi-access = free }} In the 1920s Dutch scientist [[Frits Warmolt Went]] and Russian scientist [[Nikolai Cholodny]] (working independently of each other) conclusively showed that asymmetric accumulation of a growth hormone was responsible for this bending. In 1933 this hormone was finally isolated by Kögl, Haagen-Smit and Erxleben and given the name '[[auxin]]'.{{cite journal | vauthors = Wieland OP, De Ropp RS, Avener J | title = Identity of auxin in normal urine | journal = Nature | volume = 173 | issue = 4408 | pages = 776–7 | date = April 1954 | pmid = 13165644 | doi = 10.1038/173776a0 | bibcode = 1954Natur.173..776W | s2cid = 4225835 | url = https://www.nature.com/articles/173776a0 }}{{cite journal | vauthors = Holland JJ, Roberts D, Liscum E | title = Understanding phototropism: from Darwin to today | journal = Journal of Experimental Botany | volume = 60 | issue = 7 | pages = 1969–78 | date = 2009-05-01 | pmid = 19357428 | doi = 10.1093/jxb/erp113 | doi-access = free }} [34] => [35] => ===Oliver and Schäfer (1894)=== [36] => British physician [[George Oliver (physician)|George Oliver]] and physiologist [[Edward Albert Sharpey-Schafer|Edward Albert Schäfer]], professor at University College London, collaborated on the physiological effects of adrenal extracts. They first published their findings in two reports in 1894, a full publication followed in 1895.{{cite journal | vauthors = | title = Proceedings of the Physiological Society, March 10, 1894. No. I | journal = The Journal of Physiology | volume = 16 | issue = 3–4 | pages = i-viii | date = April 1894 | pmid = 16992168 | pmc = 1514529 | doi = 10.1113/jphysiol.1894.sp000503 }}{{cite journal | vauthors = Oliver G, Schäfer EA | title = The Physiological Effects of Extracts of the Suprarenal Capsules | journal = The Journal of Physiology | volume = 18 | issue = 3 | pages = 230–276 | date = July 1895 | pmid = 16992252 | pmc = 1514629 | doi = 10.1113/jphysiol.1895.sp000564 }} Though frequently falsely attributed to [[secretin]], found in 1902 by Bayliss and Starling, Oliver and Schäfer's adrenal extract containing [[adrenaline]], the substance causing the physiological changes, was the first hormone to be discovered. The term hormone would later be coined by Starling.{{cite book | vauthors = Bayliss WM, Starling EH | veditors = Leicester HM |chapter=The Mechanism of Pancreatic Secretion |doi=10.4159/harvard.9780674366701.c111 |title=Source Book in Chemistry, 1900–1950 |publisher=Harvard University Press |isbn=978-0-674-36670-1 |year=1968| pages = 311–313 }} [37] => [38] => ===Bayliss and Starling (1902)=== [39] => [40] => [[William Bayliss]] and [[Ernest Starling]], a [[physiology|physiologist]] and [[biologist]], respectively, wanted to see if the [[nervous system]] had an impact on the [[human digestive system|digestive system]]. They knew that the [[pancreas]] was involved in the secretion of [[digestive fluid]]s after the passage of food from the [[stomach]] to the [[gastrointestinal tract|intestines]], which they believed to be due to the nervous system. They cut the nerves to the pancreas in an animal model and discovered that it was not nerve impulses that controlled secretion from the pancreas. It was determined that a factor secreted from the intestines into the [[bloodstream]] was stimulating the pancreas to secrete digestive fluids. This was named [[secretin]]: a hormone. [41] => [42] => ==Types of signaling== [43] => Hormonal effects are dependent on where they are released, as they can be released in different manners.{{cite book|title=Endocrine physiology | vauthors = Molina PE |date=2018|publisher=McGraw-Hill Education|isbn=978-1-260-01935-3|oclc=1034587285}} Not all hormones are released from a cell and into the blood until it binds to a receptor on a target. The major types of hormone signaling are: [44] => {| class="wikitable" [45] => |+Signaling Types - Hormones [46] => !SN [47] => !Types [48] => !Description [49] => |- [50] => |1 [51] => |[[Endocrine system|Endocrine]] [52] => |Acts on the target cells after being released into the bloodstream. [53] => |- [54] => |2 [55] => |[[Paracrine signaling|Paracrine]] [56] => |Acts on the nearby cells and does not have to enter general circulation. [57] => |- [58] => |3 [59] => |[[Autocrine signaling|Autocrine]] [60] => |Affects the cell types that secreted it and causes a biological effect. [61] => |- [62] => |4 [63] => |[[Intracrine]] [64] => |Acts intracellularly on the cells that synthesized it. [65] => |} [66] => [67] => ==Chemical classes== [68] => As hormones are defined functionally, not structurally, they may have diverse chemical structures. Hormones occur in [[multicellular organism]]s ([[plant]]s, [[animal]]s, [[fungus|fungi]], [[brown algae]], and [[red algae]]). These compounds occur also in [[unicellular organism]]s, and may act as [[signaling molecule]]s however there is no agreement that these molecules can be called hormones.{{cite journal | vauthors = Lenard J | title = Mammalian hormones in microbial cells | journal = Trends in Biochemical Sciences | volume = 17 | issue = 4 | pages = 147–50 | date = April 1992 | pmid = 1585458 | doi = 10.1016/0968-0004(92)90323-2 }}{{cite journal| vauthors = Janssens PM|title=Did vertebrate signal transduction mechanisms originate in eukaryotic microbes?|journal=Trends in Biochemical Sciences|volume=12|pages=456–459|doi=10.1016/0968-0004(87)90223-4|year=1987}} [69] => [70] => === Vertebrates === [71] => {{Further|List of human hormones}} [72] => {| class="wikitable" [73] => |+Hormone types in Vertebrates [74] => !SN [75] => !Types [76] => !Description [77] => |- [78] => |1 [79] => |Proteins/ [80] => Peptides [81] => |[[Peptide hormone]]s are made of a chain of [[amino acid]]s that can range from just 3 to hundreds. Examples include [[oxytocin]] and [[insulin]]. Their sequences are encoded in [[DNA]] and can be modified by [[alternative splicing]] and/or [[post-translational modification]]. They are packed in vesicles and are [[hydrophile|hydrophilic]], meaning that they are soluble in water. Due to their hydrophilicity, they can only bind to receptors on the membrane, as travelling through the membrane is unlikely. However, some hormones can bind to intracellular receptors through an [[intracrine]] mechanism. [82] => |- [83] => |2 [84] => |Amino Acid [85] => Derivatives [86] => |[[Amino acid]] hormones are derived from amino acids, most commonly [[Tyrosine]]. They are stored in vesicles. Examples include [[Melatonin]] and [[Thyroxine]]. [87] => |- [88] => |3 [89] => |Steroids [90] => |[[Steroid]] hormones are derived from cholesterol. Examples include the sex hormones [[estradiol]] and [[testosterone]] as well as the stress hormone [[cortisol]].{{cite book| vauthors = Marieb E |title=Anatomy & physiology|publisher=Pearson Education, Inc|year=2014|isbn=978-0-321-86158-0|location=Glenview, IL}} Steroids contain four fused rings. They are [[lipophilic]] and hence can cross membranes to bind to intracellular [[nuclear receptor]]s. [91] => |- [92] => |4 [93] => |Eicosanoids [94] => |[[Eicosanoid]]s hormones are derived from lipids such as [[arachidonic acid]], [[lipoxin]]s, thromboxanes and [[prostaglandin]]s. Examples include [[prostaglandin]] and [[thromboxane]]. These hormones are produced by [[cyclooxygenase]]s and [[lipoxygenase]]s. They are hydrophobic and act on membrane receptors. [95] => |- [96] => |5 [97] => |Gases [98] => |Ethylene and Nitric Oxide [99] => |}[[File:1802 Examples of Amine Peptide Protein and Steroid Hormone Structure.jpg|thumb|00px|Different types of hormones are secreted in the human body, with different biological roles and functions.]] [100] => [101] => === Invertebrates === [102] => Compared with vertebrates, [[insect]]s and [[crustacean]]s possess a number of structurally unusual hormones such as the [[juvenile hormone]], a [[sesquiterpenoid]].{{cite journal | vauthors = Heyland A, Hodin J, Reitzel AM | title = Hormone signaling in evolution and development: a non-model system approach | journal = BioEssays | volume = 27 | issue = 1 | pages = 64–75 | date = January 2005 | pmid = 15612033 | doi = 10.1002/bies.20136 }} [103] => [104] => === Plants === [105] => {{Further|Plant hormone}} [106] => Examples include [[abscisic acid]], [[auxin]], [[cytokinin]], [[Ethylene as a plant hormone|ethylene]], and [[gibberellin]].{{cite journal | vauthors = Wang YH, Irving HR | title = Developing a model of plant hormone interactions | journal = Plant Signaling & Behavior | volume = 6 | issue = 4 | pages = 494–500 | date = April 2011 | pmid = 21406974 | pmc = 3142376 | doi = 10.4161/psb.6.4.14558 | bibcode = 2011PlSiB...6..494W }} [107] => [108] => ==Receptors== [109] => [[File:Steroid and Lipid Hormones.svg|thumb|400px|The left diagram shows a steroid (lipid) hormone (1) entering a cell and (2) binding to a receptor protein in the nucleus, causing (3) mRNA synthesis which is the first step of protein synthesis. The right side shows protein hormones (1) binding with receptors which (2) begins a transduction pathway. The transduction pathway ends (3) with transcription factors being activated in the nucleus, and protein synthesis beginning. In both diagrams, a is the hormone, b is the cell membrane, c is the cytoplasm, and d is the nucleus.]] Most hormones initiate a cellular response by initially binding to either [[cell surface receptor]]s or [[intracellular receptor]]s. A cell may have several different [[Receptor (biochemistry)|receptors]] that recognize the same hormone but activate different [[signal transduction]] pathways, or a cell may have several different receptors that recognize different hormones and activate the same biochemical pathway.{{Cite web|url=https://www.khanacademy.org/science/biology/cell-signaling/mechanisms-of-cell-signaling/a/intracellular-signal-transduction|title=Signal relay pathways|website=Khan Academy|access-date=2019-11-13}} [110] => [111] => Receptors for most [[peptide hormone|peptide]] as well as many [[eicosanoid]] hormones are embedded in the [[cell membrane]] as cell surface receptors, and the majority of these belong to the [[G protein-coupled receptor]] (GPCR) class of seven [[alpha helix]] [[transmembrane]] proteins. The interaction of hormone and receptor typically triggers a cascade of secondary effects within the [[cytoplasm]] of the cell, described as [[signal transduction]], 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 [[second messenger|secondary messengers]] (e.g., [[cyclic AMP]]). Some [[protein hormone]]s also interact with [[intracellular]] receptors located in the [[cytoplasm]] or [[cell nucleus|nucleus]] by an [[intracrine]] mechanism.{{Cite journal| vauthors = Lodish H, Berk A, Zipursky SL, Matsudaira P, Baltimore D, Darnell J |date=2000|title=G Protein –Coupled Receptors and Their Effectors|url=https://www.ncbi.nlm.nih.gov/books/NBK21718/|journal=Molecular Cell Biology | edition = 4th }}{{cite journal | vauthors = Rosenbaum DM, Rasmussen SG, Kobilka BK | title = The structure and function of G-protein-coupled receptors | journal = Nature | volume = 459 | issue = 7245 | pages = 356–63 | date = May 2009 | pmid = 19458711 | pmc = 3967846 | doi = 10.1038/nature08144 | bibcode = 2009Natur.459..356R }} [112] => [113] => For [[steroid hormone|steroid]] or [[thyroid hormone|thyroid]] hormones, their [[steroid hormone receptor|receptors]] are located [[intracellular|inside the cell]] within the [[cytoplasm]] of the target cell. These receptors belong to the [[nuclear receptor]] family of ligand-activated [[transcription factor]]s. To bind their receptors, these hormones must first cross the cell membrane. They can do so because they are lipid-soluble. The combined hormone-receptor [[protein complex|complex]] then moves across the nuclear membrane into the nucleus of the cell, where it binds to specific [[DNA sequences]], regulating the expression of certain [[genes]], and thereby increasing the levels of the proteins encoded by these genes.{{cite journal | vauthors = Beato M, Chávez S, Truss M | title = Transcriptional regulation by steroid hormones | journal = Steroids | volume = 61 | issue = 4 | pages = 240–51 | date = April 1996 | pmid = 8733009 | doi = 10.1016/0039-128X(96)00030-X | s2cid = 20654561 }} However, it has been shown that not all steroid receptors are located inside the cell. Some are associated with the [[plasma membrane]].{{cite journal | vauthors = Hammes SR | title = The further redefining of steroid-mediated signaling | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 100 | issue = 5 | pages = 2168–70 | date = March 2003 | pmid = 12606724 | pmc = 151311 | doi = 10.1073/pnas.0530224100 | bibcode = 2003PNAS..100.2168H | doi-access = free }} [114] => [115] => ==Effects in humans== [116] => Hormones have the following effects on the body:{{Cite book|title=Clearopathy| vauthors = Lall S |publisher=Partridge Publishing India|year=2013|isbn=978-1-4828-1588-7|location=India|pages=1}} [117] => * stimulation or inhibition of growth [118] => * wake-sleep cycle and other [[circadian rhythm]]s [119] => * [[mood swing]]s [120] => * induction or suppression of [[apoptosis]] (programmed cell death) [121] => * activation or inhibition of the [[immune system]] [122] => * regulation of [[metabolism]] [123] => * preparation of the body for [[mating]], [[fighting]], [[fight-or-flight response|fleeing]], and other activity [124] => * preparation of the body for a new phase of life, such as [[puberty]], [[parenting]], and [[menopause]] [125] => * control of the [[reproductive cycle]] [126] => * hunger cravings [127] => [128] => A hormone may also regulate the production and release of other hormones. Hormone signals control the internal environment of the body through [[homeostasis]]. [129] => [130] => ==Regulation== [131] => The rate of hormone biosynthesis and secretion is often regulated by a [[homeostasis|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.{{cite book | vauthors = Campbell M, Jialal I | chapter = Physiology, Endocrine Hormones |date=2019 |url=http://www.ncbi.nlm.nih.gov/books/NBK538498/ | title = StatPearls |publisher=StatPearls Publishing |pmid=30860733|access-date=13 November 2019 }}{{cite journal | vauthors = Röder PV, Wu B, Liu Y, Han W | title = Pancreatic regulation of glucose homeostasis | journal = Experimental & Molecular Medicine | volume = 48 | issue = 3 | pages = e219 | date = March 2016 | pmid = 26964835 | pmc = 4892884 | doi = 10.1038/emm.2016.6 }} [132] => [[File:Negative Feedback Gif.gif|thumb|Blood glucose levels are maintained at a constant level in the body by a negative feedback mechanism. When the blood glucose level is too high, the pancreas secretes insulin and when the level is too low, the pancreas then secretes glucagon. The flat line shown represents the homeostatic set point. The sinusoidal line represents the blood glucose level.]] [133] => Hormone secretion can be stimulated and inhibited by: [134] => * Other hormones (''stimulating''- or ''releasing'' -hormones) [135] => * Plasma concentrations of ions or nutrients, as well as binding [[globulin]]s [136] => * [[Neuron]]s and mental activity [137] => * Environmental changes, e.g., of light or temperature [138] => [139] => One special group of hormones is the [[tropic hormone]]s that stimulate the hormone production of other [[endocrine system|endocrine glands]]. For example, [[thyroid-stimulating hormone]] (TSH) causes growth and increased activity of another endocrine gland, the [[thyroid]], which increases output of [[thyroid hormone]]s.{{Cite book|title=Allergy-hormone links| vauthors = Shah SB, Saxena R |date=2012 |publisher= Jaypee Brothers Medical Publishers (P) Ltd |isbn=978-93-5025-013-6 |location=New Delhi |oclc=761377585 }} [140] => [141] => To release active hormones quickly into the [[circulatory system|circulation]], hormone biosynthetic cells may produce and store biologically inactive hormones in the form of [[prehormone|pre-]] or [[prohormone]]s. These can then be quickly converted into their active hormone form in response to a particular stimulus. [142] => [143] => [[Eicosanoid]]s are considered to act as local hormones. They are considered to be "local" because they possess specific effects on target cells close to their site of formation. They also have a rapid degradation cycle, making sure they do not reach distant sites within the body."Eicosanoids". www.rpi.edu. Retrieved 2017-02-08. [144] => [145] => Hormones are also regulated by receptor agonists. Hormones are ligands, which are any kinds of molecules that produce a signal by binding to a receptor site on a protein. Hormone effects can be inhibited, thus regulated, by competing ligands that bind to the same target receptor as the hormone in question. When a competing ligand is bound to the receptor site, the hormone is unable to bind to that site and is unable to elicit a response from the target cell. These competing ligands are called antagonists of the hormone.{{Cite book|title=Human physiology : an integrated approach| vauthors = Silverthorn DU, Johnson BR, Ober WC, Ober CW |isbn=978-0-321-98122-6|edition=Seventh|location= San Francisco | publisher = Pearson |oclc=890107246|year = 2016}} [146] => [147] => ==Therapeutic use== [148] => {{Main|Hormone therapy}} [149] => Many hormones and their [[structural analog|structural]] and [[functional analog (chemistry)|functional analogs]] are used as [[medication]]. The most commonly prescribed hormones are [[estrogen]]s and [[progestogen]]s (as methods of [[hormonal contraception]] and as [[Hormone replacement therapy (menopause)|HRT]]),{{cite web |url= https://my.clevelandclinic.org/health/treatments/15245-hormone-therapy |title= Hormone Therapy |publisher= Cleveland Clinic}} [[thyroxine]] (as [[levothyroxine]], for [[hypothyroidism]]) and [[steroid]]s (for [[autoimmune disease]]s and several [[pulmonology|respiratory disorders]]). [[Insulin]] is used by many [[diabetes mellitus|diabetics]]. Local preparations for use in [[otolaryngology]] often contain [[pharmacology|pharmacologic]] equivalents of [[adrenaline]], while [[steroid]] and [[vitamin D]] creams are used extensively in [[dermatology|dermatological]] practice.{{Cite book | vauthors = Sfetcu N |url=https://books.google.com/books?id=8jF-AwAAQBAJ&dq=Local+preparations+for+use+in+otolaryngology+often+contain+pharmacologic+equivalents+of+adrenaline%2C+while+steroid+and+vitamin+D+creams+are+used+extensively+in+dermatological+practice&pg=PA1126 |title=Health & Drugs: Disease, Prescription & Medication |date=2014-05-02 |publisher=Nicolae Sfetcu |language=en}} [150] => [151] => A "pharmacologic dose" or "supraphysiological 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, though not without potentially adverse side effects. An example is the ability of pharmacologic doses of [[glucocorticoid]]s to suppress [[inflammation]]. [152] => [153] => ==Hormone-behavior interactions== [154] => At the neurological level, behavior can be inferred based on hormone concentration, which in turn are influenced by hormone-release patterns; the numbers and locations of hormone receptors; and the efficiency of hormone receptors for those involved in gene transcription. Hormone concentration does not incite behavior, as that would undermine other external stimuli; however, it influences the system by increasing the probability of a certain event to occur.Nelson, R. J. (2021). Hormones & behavior. In R. Biswas-Diener & E. Diener (Eds), ''Noba textbook series: Psychology.'' Champaign, IL: DEF publishers. Retrieved from http://noba.to/c6gvwu9m [155] => [156] => Not only can hormones influence behavior, but also behavior and the environment can influence hormone concentration.{{Citation| vauthors = Nelson RJ |title=Hormones and Behavior: Basic Concepts|date=2010|url=https://linkinghub.elsevier.com/retrieve/pii/B9780080453378002369|encyclopedia=Encyclopedia of Animal Behavior|pages=97–105|publisher=Elsevier|language=en|doi=10.1016/b978-0-08-045337-8.00236-9|isbn=978-0-08-045337-8|s2cid=7479319 |access-date=2021-11-18}} Thus, a feedback loop is formed, meaning behavior can affect hormone concentration, which in turn can affect behavior, which in turn can affect hormone concentration, and so on.{{cite journal | vauthors = Garland T, Zhao M, Saltzman W | title = Hormones and the Evolution of Complex Traits: Insights from Artificial Selection on Behavior | journal = Integrative and Comparative Biology | volume = 56 | issue = 2 | pages = 207–24 | date = August 2016 | pmid = 27252193 | pmc = 5964798 | doi = 10.1093/icb/icw040 }} For example, hormone-behavior feedback loops are essential in providing constancy to episodic hormone secretion, as the behaviors affected by episodically secreted hormones directly prevent the continuous release of said hormones.{{Cite book|url=https://www.worldcat.org/oclc/1022119040|title=Principles of hormone/behavior relations|publisher=[[Academic Press]]| vauthors = Pfaff DW, Rubin RT, Schneider JE, Head GA |year=2018|isbn=978-0-12-802667-0|edition=2nd|location=London, United Kingdom|language=en-GB|oclc=1022119040}} [157] => [158] => Three broad stages of reasoning may be used to determine if a specific hormone-behavior interaction is present within a system:{{citation needed|date=May 2022}} [159] => * The frequency of occurrence of a hormonally dependent behavior should correspond to that of its hormonal source. [160] => * A hormonally dependent behavior is not expected if the hormonal source (or its types of action) is non-existent. [161] => * The reintroduction of a missing behaviorally dependent hormonal source (or its types of action) is expected to bring back the absent behavior. [162] => [163] => ==Comparison with neurotransmitters== [164] => Though colloquially oftentimes used interchangeably, there are various clear distinctions between hormones and [[neurotransmitter]]s:{{Cite book|title=Campbell biology | vauthors = Reece JB, Urry LA, Cain ML, Wasserman SA, Minorsky PV, Jackson RB, Campbell NA |isbn=978-0-321-77565-8 |edition=Tenth |location=Boston | publisher = Pearson |oclc=849822337 |year = 2014}}{{Cite book|url=https://archive.org/details/essentialneurosc0000sieg|title=Essential neuroscience| vauthors = Siegel A, Sapru H, Hreday N, Siegel H |date=2006|publisher=Lippincott Williams & Wilkins|isbn=0-7817-5077-6|location=Philadelphia|oclc=60650938|url-access=registration}} [165] => * A hormone can perform functions over a larger spatial and temporal scale than can a neurotransmitter, which often acts in micrometer-scale distances.{{Cite book|url=https://www.worldcat.org/oclc/44627256|title=Neuroscience|date=2001|publisher=Sinauer Associates| vauthors = Purves D, Williams SM |isbn=0-87893-742-0|edition=2nd|location=Sunderland, Mass.|oclc=44627256}} [166] => * Hormonal signals can travel virtually anywhere in the circulatory system, whereas neural signals are restricted to pre-existing [[nerve tract]]s. [167] => * Assuming the travel distance is equivalent, neural signals can be transmitted much more quickly (in the range of milliseconds) than can hormonal signals (in the range of seconds, minutes, or hours). Neural signals can be sent at speeds up to 100 meters per second.{{Cite book|title=Molecular biology of the cell| vauthors = Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P |date=2002|publisher=Garland Science |isbn=0-8153-3218-1|edition=4th|location=New York|oclc=48122761}} [168] => * Neural signalling is an all-or-nothing (digital) action, whereas hormonal signalling is an action that can be continuously variable as it is dependent upon hormone concentration. [169] => [170] => Neurohormones are a type of hormone that share a commonality with neurotransmitters. They are produced by endocrine cells that receive input from neurons, or neuroendocrine cells.{{Cite book|url=https://archive.org/details/isbn_9780716738732|title=Life, the science of biology|date=2001|publisher=Sinauer Associates| vauthors = Purves WK, Kirkwood W | isbn= 0-7167-3873-2|edition=6th|location=Sunderland, MA|oclc=45064683|url-access=registration}} Both classic hormones and neurohormones are secreted by endocrine tissue; however, neurohormones are the result of a combination between endocrine reflexes and neural reflexes, creating a neuroendocrine pathway. While endocrine pathways produce chemical signals in the form of hormones, the neuroendocrine pathway involves the electrical signals of neurons. In this pathway, the result of the electrical signal produced by a neuron is the release of a chemical, which is the neurohormone'''.''' Finally, like a classic hormone, the neurohormone is released into the bloodstream to reach its target. [171] => [172] => ==Binding proteins== [173] => Hormone transport and the involvement of binding proteins is an essential aspect when considering the function of hormones.{{Cite journal | journal = OpenStaxCollege |date=2013-03-06 |title=Hormones |url=https://pressbooks-dev.oer.hawaii.edu/anatomyandphysiology/chapter/hormones/ |language=en}} [174] => [[File:Hormones.svg|thumb|This is a diagram that represents and describer what hormones are and their activity in the bloodstream. Hormones flow in and out of the bloodstream and are able to bind to Target cells to activate the role of the hormone. This is with the help of the bloodstream flow and the secreting cell. Hormones regulate: metabolism, growth and development, tissue function, sleep, reproduction, etc. This diagram also lists the important hormones in a human body.]] [175] => The formation of a complex with a binding protein has several benefits: the effective half-life of the bound hormone is increased, and a reservoir of bound hormones is created, which evens the variations in concentration of unbound hormones (bound hormones will replace the unbound hormones when these are eliminated).Boron WF, Boulpaep EL. Medical physiology: a cellular and molecular approach. Updated 2. Philadelphia, Pa: Saunders Elsevier; 2012. An example of the usage of hormone-binding proteins is in the thyroxine-binding protein which carries up to 80% of all thyroxine in the body, a crucial element in regulating the metabolic rate.{{Cite journal| vauthors = Oppenheimer JH |date=1968-05-23|title=Role of Plasma Proteins in the Binding, Distribution and Metabolism of the Thyroid Hormones|url=http://www.nejm.org/doi/abs/10.1056/NEJM196805232782107|journal=New England Journal of Medicine|language=en|volume=278|issue=21|pages=1153–1162|doi=10.1056/NEJM196805232782107|pmid=4172185|issn=0028-4793}} [176] => [177] => == See also == [178] => {{Div col|colwidth=10em}} [179] => * [[Autocrine signaling]] [180] => * [[Adipokine]] [181] => * [[Cytokine]] [182] => * [[Hepatokine]] [183] => * [[Endocrine disease]] [184] => * [[Endocrine system]] [185] => * [[Endocrinology]] [186] => * [[Environmental hormones]] [187] => * [[Growth factor]] [188] => * [[Intracrine]] [189] => * [[List of investigational sex-hormonal agents]] [190] => * [[Metabolomics]] [191] => * [[Myokine]] [192] => * [[Neohormone]] [193] => * [[Neuroendocrinology]] [194] => * [[Paracrine signaling]] [195] => * [[Plant hormone]]s, a.k.a. plant growth regulators [196] => * [[Semiochemical]] [197] => * [[Sex-hormonal agent]] [198] => * [[Sexual motivation and hormones]] [199] => * [[Xenohormone]] [200] => * [[List of human hormones]] [201] => {{Div col end}} [202] => [203] => == References == [204] => {{Reflist|30em}} [205] => [206] => == External links == [207] => * [http://crdd.osdd.net/raghava/hmrbase/ HMRbase: A database of hormones and their receptors] [208] => * {{MeSH name|Hormones}} [209] => * {{Merriam-Webster|Hormone}} [210] => [211] => {{Hormones}} [212] => {{Signal transduction}} [213] => [214] => {{Authority control}} [215] => [216] => [[Category:Hormones|*]] [217] => [[Category:Physiology]] [218] => [[Category:Endocrinology]] [219] => [[Category:Cell signaling]] [220] => [[Category:Signal transduction]] [221] => [[Category:Human female endocrine system]] [] => )
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Hormone

Hormones are chemical messengers produced by various glands and tissues in the human body. They play a crucial role in regulating a wide range of physiological processes, including growth and development, metabolism, reproduction, and mood.

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They play a crucial role in regulating a wide range of physiological processes, including growth and development, metabolism, reproduction, and mood. The Wikipedia page on hormones provides a comprehensive overview of these chemical substances, exploring their types, functions, and mechanisms of action. The page begins by introducing the concept of hormones and explaining their importance in maintaining homeostasis within the body. It then delves into the different types of hormones, categorizing them based on their chemical structure and mode of action. The main classes covered include steroids, peptide hormones, and amino acid-derived hormones. Beyond classification, the page investigates the major endocrine glands and organs responsible for hormone production, such as the pituitary gland, thyroid gland, adrenal glands, and pancreas. It explores their respective hormone secretions and their roles in various physiological processes. Additionally, the page identifies other organs and tissues that produce hormones, including the hypothalamus, ovaries, testes, and placenta. From there, the discussion expands to hormone regulation and signaling mechanisms. It explains how hormones circulate in the blood and reach their target cells, where they bind to specific receptors, triggering various physiological responses. The page also examines feedback loops and feedback inhibition, illustrating how the body maintains hormone balance. Furthermore, the Wikipedia page highlights specific hormones and their functions. It outlines the role of hormones in growth and development, detailing the impact of growth hormone, insulin-like growth factors, and sex hormones. It also discusses the involvement of hormones in metabolism, addressing insulin, glucagon, and thyroid hormones. The page delves into the crucial roles of hormones in reproduction and sexual development, covering reproductive hormones such as follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone. It further explores the impact of hormones on mood and behavior, examining the effects of serotonin, dopamine, and endorphins. The article concludes by summarizing hormone-related disorders and their treatment, such as hypothyroidism, diabetes, and hormonal imbalances. It emphasizes the importance of hormone therapy and the role of medications in restoring hormonal balance. Overall, the Wikipedia page on hormones provides a comprehensive overview of these vital chemical messengers, covering their types, functions, regulations, and related disorders. It serves as a valuable resource for anyone seeking knowledge in the field of endocrinology and human physiology.

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