An abbreviation is a shortened form of a word or phrase. It consists of a group of letters taken from the phrase. For example, the word abbreviation can itself be represented by the abbreviation abbr. abbrv. or abbrev. In strict analysis, abbreviations should not be confused with contractions, acronyms, or initialisms, with which they share some semantic and phonetic functions, though all four are connected by the term "abbreviation" in loose parlance. An abbreviation is a shortening by any method. A contraction of a word is made by omitting certain letters or syllables and bringing together the first and last letters or elements. A contraction is an abbreviation, but an abbreviation is not a contraction. Acronyms and initialisms are regarded as subsets of abbreviations, they are abbreviations that consist of the initial parts of words. Abbreviations have a long history, created; this might be done to save time and space, to provide secrecy. Shortened words were used and initial letters were used to represent words in specific applications.
In classical Greece and Rome, the reduction of words to single letters was common. In Roman inscriptions, "Words were abbreviated by using the initial letter or letters of words, most inscriptions have at least one abbreviation." However, "some could have more than one meaning, depending on their context."Abbreviations in English were used from its earliest days. Manuscripts of copies of the old English poem Beowulf used many abbreviations, for example 7 or & for and, y for since, so that "not much space is wasted"; the standardisation of English in the 15th through 17th centuries included such a growth in the use of abbreviations. At first, abbreviations were sometimes represented with various suspension signs, not only periods. For example, sequences like ‹er› were replaced with ‹ɔ›, as in ‹mastɔ› for master and ‹exacɔbate› for exacerbate. While this may seem trivial, it was symptomatic of an attempt by people manually reproducing academic texts to reduce the copy time. An example from the Oxford University Register, 1503: Mastɔ subwardenɔ y ɔmēde me to you.
And wherɔ y wrot to you the last wyke that y trouyde itt good to differrɔ thelectionɔ ovɔ to quīdenaɔ tinitatis y have be thougħt me synɔ that itt woll be thenɔ a bowte mydsomɔ. The Early Modern English period, between the 15th and 17th centuries, had abbreviations like ye for Þe, used for the word the: "hence, by misunderstanding, Ye Olde Tea Shoppe."During the growth of philological linguistic theory in academic Britain, abbreviating became fashionable. The use of abbreviation for the names of J. R. R. Tolkien and his friend C. S. Lewis, other members of the Oxford literary group known as the Inklings, are sometimes cited as symptomatic of this. A century earlier in Boston, a fad of abbreviation started that swept the United States, with the globally popular term OK credited as a remnant of its influence. After World War II, the British reduced the use of the full stop and other punctuation points after abbreviations in at least semi-formal writing, while the Americans more kept such use until more and still maintain it more than Britons.
The classic example, considered by their American counterparts quite curious, was the maintenance of the internal comma in a British organisation of secret agents called the "Special Operations, Executive"—"S. O. E"—which is not found in histories written after about 1960, but before that, many Britons were more scrupulous at maintaining the French form. In French, the period only follows an abbreviation if the last letter in the abbreviation is not the last letter of its antecedent: "M." is the abbreviation for "monsieur" while "Mme" is that for "madame". Like many other cross-channel linguistic acquisitions, many Britons took this up and followed this rule themselves, while the Americans took a simpler rule and applied it rigorously. Over the years, the lack of convention in some style guides has made it difficult to determine which two-word abbreviations should be abbreviated with periods and which should not; the U. S. media tend to use periods in two-word abbreviations like United States, but not personal computer or television.
Many British publications have done away with the use of periods in abbreviations. Minimization of punctuation in typewritten material became economically desirable in the 1960s and 1970s for the many users of carbon-film ribbons since a period or comma consumed the same length of non-reusable expensive ribbon as did a capital letter. Widespread use of electronic communication through mobile phones and the Internet during the 1990s allowed for a marked rise in colloquial abbreviation; this was due to increasing popularity of textual communication services such as instant- and text messaging. SMS, for instance, supports message lengths of 160 characters at most; this brevity gave rise to an informal abbreviation scheme sometimes called Textese, with which 10% or more of the words in a typical SMS message are abbreviated. More Twitter, a popular social networking service, began driving abbreviation use with 140 character message limits. In modern English, there are several conventions for abbreviations, the choice may be confusing.
The only rule universally accepted is th
The μ-opioid receptors are a class of opioid receptors with a high affinity for enkephalins and beta-endorphin, but a low affinity for dynorphins. They are referred to as μ-opioid peptide receptors; the prototypical μ-opioid receptor agonist is morphine, the primary psychoactive alkaloid in opium. It is an inhibitory G-protein coupled receptor that activates the Gi alpha subunit, inhibiting adenylate cyclase activity, lowering cAMP levels. A cryo-electron microscopy structure of the µ-opioid receptor–Gi protein complex was published in 2018. Three variants of the μ-opioid receptor are well characterized, though RT-PCR has identified up to 10 total splice variants in humans, they can exist either postsynaptically depending upon cell types. The μ-opioid receptors exist presynaptically in the periaqueductal gray region, in the superficial dorsal horn of the spinal cord. Other areas where they have been located include the external plexiform layer of the olfactory bulb, the nucleus accumbens, in several layers of the cerebral cortex, in some of the nuclei of the amygdala, as well as the nucleus of the solitary tract.
Some MORs are found in the intestinal tract. Activation of these receptors inhibits peristaltic action which causes constipation, a major side effect of μ agonists. MOR can mediate acute changes in neuronal excitability via suppression of presynaptic release of GABA. Activation of the MOR leads to different effects on dendritic spines depending upon the agonist, may be an example of functional selectivity at the μ-receptor; the physiological and pathological roles of these two distinct mechanisms remain to be clarified. Both might be involved in opioid addiction and opioid-induced deficits in cognition. Activation of the μ-opioid receptor by an agonist such as morphine causes analgesia, sedation reduced blood pressure, nausea, decreased respiration and decreased bowel motility leading to constipation; some of these effects, such as analgesia, euphoria and decreased respiration, tend to lessen with continued use as tolerance develops. Miosis and reduced bowel motility tend to persist; the canonical MOR1 isoform is responsible for morphine-induced analgesia, whereas the alternatively spliced MOR1D isoform is required for morphine-induced itching.
As with other G protein-coupled receptors, signalling by the μ-opioid receptor is terminated through several different mechanisms, which are upregulated with chronic use, leading to rapid tachyphylaxis. The most important regulatory proteins for the MOR are the β-arrestins arrestin beta 1 and arrestin beta 2, the RGS proteins RGS4, RGS9-2, RGS14, RGSZ2. Long-term or high-dose use of opioids may lead to additional mechanisms of tolerance becoming involved; this includes downregulation of MOR gene expression, so the number of receptors presented on the cell surface is reduced, as opposed to the more short-term desensitisation induced by β-arrestins or RGS proteins. Another long-term adaptation to opioid use can be upregulation of glutamate and other pathways in the brain which can exert an opioid-opposing effect, so reduce the effects of opioid drugs by altering downstream pathways, regardless of MOR activation. Fatal opioid overdose occurs due to bradypnea and decreased cardiac output. A potentiation effect occurs when opioids are combined with ethanol, benzodiazepines, or barbiturates, which results in an increased risk for overdose to occur.
Substantial tolerance to respiratory depression develops and tolerant individuals can withstand larger doses. However, tolerance to respiratory depression is lost just as during withdrawal. Many overdoses occur in people who misuse their medication after being in withdrawal long enough to lose the tolerance to respiratory depression. Less massive overdoses have been known to cause circulatory collapse. Opioid overdoses can be reversed through the use of opioid antagonists, naloxone being the most used example. Δ-opioid receptor κ-opioid receptor "Opioid Receptors: μ". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Mu+Opioid+Receptor at the US National Library of Medicine Medical Subject Headings Human OPRM1 genome location and OPRM1 gene details page in the UCSC Genome Browser
Dopamine is an organic chemical of the catecholamine and phenethylamine families. It functions both as a hormone and a neurotransmitter, plays several important roles in the brain and body, it is an amine synthesized by removing a carboxyl group from a molecule of its precursor chemical L-DOPA, synthesized in the brain and kidneys. Dopamine is synthesized in plants and most animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons to send signals to other nerve cells; the brain includes several distinct dopamine pathways, one of which plays a major role in the motivational component of reward-motivated behavior. The anticipation of most types of rewards increases the level of dopamine in the brain, many addictive drugs increase dopamine release or block its reuptake into neurons following release. Other brain dopamine pathways are involved in motor control and in controlling the release of various hormones; these pathways and cell groups form a dopamine system, neuromodulatory.
In popular culture and media, dopamine is seen as the main chemical of pleasure, but the current opinion in pharmacology is that dopamine instead confers motivational salience. Outside the central nervous system, dopamine functions as a local paracrine messenger. In blood vessels, it acts as a vasodilator. With the exception of the blood vessels, dopamine in each of these peripheral systems is synthesized locally and exerts its effects near the cells that release it. Several important diseases of the nervous system are associated with dysfunctions of the dopamine system, some of the key medications used to treat them work by altering the effects of dopamine. Parkinson's disease, a degenerative condition causing tremor and motor impairment, is caused by a loss of dopamine-secreting neurons in an area of the midbrain called the substantia nigra, its metabolic precursor L-DOPA can be manufactured. There is evidence that schizophrenia involves altered levels of dopamine activity, most antipsychotic drugs used to treat this are dopamine antagonists which reduce dopamine activity.
Similar dopamine antagonist drugs are some of the most effective anti-nausea agents. Restless legs syndrome and attention deficit hyperactivity disorder are associated with decreased dopamine activity. Dopaminergic stimulants can be addictive in high doses, but some are used at lower doses to treat ADHD. Dopamine itself is available as a manufactured medication for intravenous injection: although it cannot reach the brain from the bloodstream, its peripheral effects make it useful in the treatment of heart failure or shock in newborn babies. A dopamine molecule consists of a catechol structure with one amine group attached via an ethyl chain; as such, dopamine is the simplest possible catecholamine, a family that includes the neurotransmitters norepinephrine and epinephrine. The presence of a benzene ring with this amine attachment makes it a substituted phenethylamine, a family that includes numerous psychoactive drugs. Like most amines, dopamine is an organic base; as a base, it is protonated in acidic environments.
The protonated form is water-soluble and stable, but can become oxidized if exposed to oxygen or other oxidants. In basic environments, dopamine is not protonated. In this free base form, it is less water-soluble and more reactive; because of the increased stability and water-solubility of the protonated form, dopamine is supplied for chemical or pharmaceutical use as dopamine hydrochloride—that is, the hydrochloride salt, created when dopamine is combined with hydrochloric acid. In dry form, dopamine hydrochloride is a fine colorless powder. Dopamine is synthesized in a restricted set of cell types neurons and cells in the medulla of the adrenal glands; the primary and minor metabolic pathways are: Primary: L-Phenylalanine → L-Tyrosine → L-DOPA → Dopamine Minor: L-Phenylalanine → L-Tyrosine → p-Tyramine → Dopamine Minor: L-Phenylalanine → m-Tyrosine → m-Tyramine → DopamineThe direct precursor of dopamine, L-DOPA, can be synthesized indirectly from the essential amino acid phenylalanine or directly from the non-essential amino acid tyrosine.
These amino acids are found in nearly every protein and so are available in food, with tyrosine being the most common. Although dopamine is found in many types of food, it is incapable of crossing the blood–brain barrier that surrounds and protects the brain, it must therefore be synthesized inside the brain to perform its neuronal activity. L-Phenylalanine is converted into L-tyrosine by the enzyme phenylalanine hydroxylase, with molecular oxygen and tetrahydrobiopterin as cofactors. L-Tyrosine is converted into L-DOPA by the enzyme tyrosine hydroxylase, with tetrahydrobiopterin, O2, iron as cofactors. L-DOPA is converted into dopamine by the enzyme aromatic L-amino acid decarboxylase, with pyridoxal phosphate as the cofactor. Dopamine itself is used as precursor in the synthesis o
Morpheus is a god associated with sleep and dreams. In Ovid's Metamorphoses he is the son of Sleep. From the medieval period, the name began to stand more for the god of dreams, or of sleep. In Ovid's Metamorphoses, Morpheus is one of the thousand sons of Somnus, his name derives from the Greek word for form, his function was to appear in dreams in human guise. According to Ovid "no other is more skilled than he in representing the gait, the features, the speech of men. Like other gods associated with sleep, Ovid makes. Ovid called Morpheus and his brothers, the other sons of Somnus, the Somnia, saying that they appear in dreams "mimicking many forms". Ovid gives names to two more of these sons of Sleep. One called Icelos, by the gods, but Phobetor by men, "takes the form of beast or bird or the long serpent", Phantasos, who "puts on deceptive shapes of earth, water, all lifeless things"; the three brothers' names are found nowhere earlier than Ovid, are Ovidian inventions. Tripp calls these three figures "literary, not mythical concepts".
However Griffin suggests that this division of dream forms between Morpheus and his brothers including their names, may have been of Hellenistic origin. Robert Burton, in his 1621 Anatomy of Melancholy, refers to a depiction of Morpheus, saying "Philostratus paints in a white and black coat, with a horn and ivory box full of dreams, of the same colours, to signify good and bad". In Carl Michael Bellman's Fredman's Epistle No. 72, "Glimmande nymf", Morpheus is invoked as the "god of sleep". Friedrich Sertürner derived the name of the opiate drug morphine from the name of Morpheus. Gates of horn and ivory Oneiroi Britten Austin, The Life and Songs of Carl Michael Bellman: Genius of the Swedish Rococo. Allhem, Malmö American-Scandinavian Foundation, New York, 1967. ISBN 978-3-932759-00-0. Burton, The Anatomy of Melancholy, New York: J. W. Moore, J. Wiley, 1850. Online version at the University of Michigan Library. Griffin, A. H. F. A Commentary on Ovid, Metamorphoses XI, Hermathena, 162/163, Dublin, JSTOR 23041237.
Grimal, The Dictionary of Classical Mythology, Wiley-Blackwell, 1996, ISBN 9780631201021. Kearns, E. "Morpheus", in S. Hornblower & A. Spawforth, Oxford Classical Dictionary, Oxford, ISBN 9780198661726CS1 maint: Uses editors parameter. Ovid. Metamorphoses, Volume II: Books 9-15. Translated by Frank Justus Miller. Revised by G. P. Goold. Loeb Classical Library No. 43. Cambridge, Massachusetts: Harvard University Press, 1916. Online version at Harvard University Press. Tripp, Crowell's Handbook of Classical Mythology, Ty Crowell Co. ISBN 069022608X
Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use disorder, reversing opioid overdose, suppressing cough, suppressing opioid induced constipation, as well as for executions in the United States. Potent opioids such as carfentanil are only approved for veterinary use. Opioids are frequently used non-medically for their euphoric effects or to prevent withdrawal. Side effects of opioids may include itchiness, nausea, respiratory depression and euphoria. Tolerance and dependence will develop with continuous use, requiring increasing doses and leading to a withdrawal syndrome upon abrupt discontinuation; the euphoria attracts recreational use and frequent, escalating recreational use of opioids results in addiction. An overdose or concurrent use with other depressant drugs results in death from respiratory depression.
Opioids act by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract. These receptors mediate the somatic effects of opioids. Opioid drugs include partial agonists, like the anti-diarrhea drug loperamide and antagonists like naloxegol for opioid-induced constipation, which do not cross the blood-brain barrier, but can displace other opioids from binding to those receptors; because opioids are addictive and may result in fatal overdose, most are controlled substances. In 2013, between 28 and 38 million people used opioids illicitly. In 2011, an estimated 4 million people in the United States used opioids recreationally or were dependent on them; as of 2015, increased rates of recreational use and addiction are attributed to over-prescription of opioid medications and inexpensive illicit heroin. Conversely, fears about over-prescribing, exaggerated side effects and addiction from opioids are blamed for under-treatment of pain.
Opioids include opiates, an older term that refers to such drugs derived from opium, including morphine itself. Other opioids are semi-synthetic and synthetic drugs such as hydrocodone and fentanyl; the terms opiate and narcotic are sometimes encountered as synonyms for opioid. Opiate is properly limited to the natural alkaloids found in the resin of the opium poppy although some include semi-synthetic derivatives. Narcotic, derived from words meaning'numbness' or'sleep', as an American legal term, refers to cocaine and opioids, their source materials. In some jurisdictions all controlled drugs are classified as narcotics; the term can have pejorative connotations and its use is discouraged where, the case. The weak opioid codeine, in low doses and combined with one or more other drugs, is available without a prescription and can be used to treat mild pain. Other opioids are reserved for the relief of moderate to severe pain. Opioids are effective for the treatment of acute pain. For immediate relief of moderate to severe acute pain opioids are the treatment of choice due to their rapid onset and reduced risk of dependence.
However a new report showed a clear risk of prolonged opioid use when opioid analgesics are initiated for an acute pain management following surgery or trauma. They have been found to be important in palliative care to help with the severe, disabling pain that may occur in some terminal conditions such as cancer, degenerative conditions such as rheumatoid arthritis. In many cases opioids are a successful long-term care strategy for those with chronic cancer pain. Guidelines have suggested that the risk of opioids is greater than their benefits when used for most non-cancer chronic conditions including headaches, back pain, fibromyalgia, thus they should be used cautiously in chronic non-cancer pain. If used the benefits and harms should be reassessed at least every three months. In treating chronic pain, opioids are an option to be tried after other less risky pain relievers have been considered, including paracetamol/acetaminophen or NSAIDs like ibuprofen or naproxen; some types of chronic pain, including the pain caused by fibromyalgia or migraine, are preferentially treated with drugs other than opioids.
The efficacy of using opioids to lessen chronic neuropathic pain is uncertain. Opioids are contraindicated as a first-line treatment for headache because they impair alertness, bring risk of dependence, increase the risk that episodic headaches will become chronic. Opioids can cause heightened sensitivity to headache pain; when other treatments fail or are unavailable, opioids may be appropriate for treating headache if the patient can be monitored to prevent the development of chronic headache. Opioids are being used more in the management of non-malignant chronic pain; this practice has now led to a new and growing problem with misuse of opioids. Because of various negative effects the use of opioids for long term management of chronic pain is not indicated unless other less risky pain relievers have been found ineffective. Chronic pain which occurs only periodically, such as that from nerve pain and fibromyalgia is better treated with medications other than opioids. Paracetamol and nonsteroidal anti-inflammatory drugs including ibuprofen and naproxen are considered safer alternatives.
They are used combined with opioids, such as paracetamol co
Scotland is a country, part of the United Kingdom. Sharing a border with England to the southeast, Scotland is otherwise surrounded by the Atlantic Ocean to the north and west, by the North Sea to the northeast and by the Irish Sea to the south. In addition to the mainland, situated on the northern third of the island of Great Britain, Scotland has over 790 islands, including the Northern Isles and the Hebrides; the Kingdom of Scotland emerged as an independent sovereign state in the Early Middle Ages and continued to exist until 1707. By inheritance in 1603, James VI, King of Scots, became King of England and King of Ireland, thus forming a personal union of the three kingdoms. Scotland subsequently entered into a political union with the Kingdom of England on 1 May 1707 to create the new Kingdom of Great Britain; the union created a new Parliament of Great Britain, which succeeded both the Parliament of Scotland and the Parliament of England. In 1801, the Kingdom of Great Britain and Kingdom of Ireland enacted a political union to create a United Kingdom.
The majority of Ireland subsequently seceded from the UK in 1922. Within Scotland, the monarchy of the United Kingdom has continued to use a variety of styles and other royal symbols of statehood specific to the pre-union Kingdom of Scotland; the legal system within Scotland has remained separate from those of England and Wales and Northern Ireland. The continued existence of legal, educational and other institutions distinct from those in the remainder of the UK have all contributed to the continuation of Scottish culture and national identity since the 1707 union with England; the Scottish Parliament, a unicameral legislature comprising 129 members, was established in 1999 and has authority over those areas of domestic policy which have been devolved by the United Kingdom Parliament. The head of the Scottish Government, the executive of the devolved legislature, is the First Minister of Scotland. Scotland is represented in the UK House of Commons by 59 MPs and in the European Parliament by 6 MEPs.
Scotland is a member of the British–Irish Council, sends five members of the Scottish Parliament to the British–Irish Parliamentary Assembly. Scotland is divided into councils. Glasgow City is the largest subdivision in Scotland in terms of population, with Highland being the largest in terms of area. "Scotland" comes from the Latin name for the Gaels. From the ninth century, the meaning of Scotia shifted to designate Gaelic Scotland and by the eleventh century the name was being used to refer to the core territory of the Kingdom of Alba in what is now east-central Scotland; the use of the words Scots and Scotland to encompass most of what is now Scotland became common in the Late Middle Ages, as the Kingdom of Alba expanded and came to encompass various peoples of diverse origins. Repeated glaciations, which covered the entire land mass of modern Scotland, destroyed any traces of human habitation that may have existed before the Mesolithic period, it is believed the first post-glacial groups of hunter-gatherers arrived in Scotland around 12,800 years ago, as the ice sheet retreated after the last glaciation.
At the time, Scotland was covered in forests, had more bog-land, the main form of transport was by water. These settlers began building the first known permanent houses on Scottish soil around 9,500 years ago, the first villages around 6,000 years ago; the well-preserved village of Skara Brae on the mainland of Orkney dates from this period. Neolithic habitation and ritual sites are common and well preserved in the Northern Isles and Western Isles, where a lack of trees led to most structures being built of local stone. Evidence of sophisticated pre-Christian belief systems is demonstrated by sites such as the Callanish Stones on Lewis and the Maes Howe on Orkney, which were built in the third millennium BCE; the first written reference to Scotland was in 320 BC by Greek sailor Pytheas, who called the northern tip of Britain "Orcas", the source of the name of the Orkney islands. During the first millennium BCE, the society changed to a chiefdom model, as consolidation of settlement led to the concentration of wealth and underground stores of surplus food.
The first Roman incursion into Scotland occurred in 79 AD. After the Roman victory, Roman forts were set along the Gask Ridge close to the Highland line, but by three years after the battle, the Roman armies had withdrawn to the Southern Uplands; the Romans erected Hadrian's Wall in northern England and the Limes Britannicus became the northern border of the Roman Empire. The Roman influence on the southern part of the country was considerable, they introduced Christianity to Scotland. Beginning in the sixth century, the area, now Scotland was divided into three areas: Pictland, a patchwork of small lordships in central Scotland; these societies were based on the family unit and had sharp divisions in wealth, although the vast majority were poor and worked full-time in subsistence agriculture. The Picts kept slaves through the ninth century. Gaelic influence over Pictland and Northumbria was facilitated by the large number of Gaelic-speaking clerics working as missionaries. Operating in the sixth ce
Euphoria is the experience of pleasure or excitement and intense feelings of well-being and happiness. Certain natural rewards and social activities, such as aerobic exercise, listening to or making music, dancing, can induce a state of euphoria. Euphoria is a symptom of certain neurological or neuropsychiatric disorders, such as mania. Romantic love and components of the human sexual response cycle are associated with the induction of euphoria. Certain drugs, many of which are addictive, can cause euphoria, which at least motivates their recreational use. Hedonic hotspots – i.e. the pleasure centers of the brain – are functionally linked. Activation of one hotspot results in the recruitment of the others. Inhibition of one hotspot results in the blunting of the effects of activating another hotspot. Therefore, the simultaneous activation of every hedonic hotspot within the reward system is believed to be necessary for generating the sensation of an intense euphoria; the word "euphoria" is derived from the Ancient Greek terms εὐφορία: εὖ eu meaning "well" and φέρω pherō meaning "to bear".
It is semantically opposite to dysphoria. A 1706 English dictionary defines euphoria as "the well bearing of the Operation of a Medicine, i.e. when the patient finds himself eas'd or reliev'd by it". In the 1860s, the English physician Thomas Laycock described euphoria as the feeling of bodily well-being and hopefulness. Sigmund Freud's 1884 monograph Über Coca described consumption of cocaine producing "the normal euphoria of a healthy person", while about 1890 the German neuropsychiatrist Carl Wernicke lectured about the "abnormal euphoria" in patients with mania. A 1903 article in The Boston Daily Globe refers to euphoria as "pleasant excitement" and "the sense of ease and well-being". In 1920 Popular Science magazine described euphoria as "a high sounding name" meaning "feeling fit": making life worth living, motivating drug use, ill formed in certain mental illnesses. Robert S. Woodworth's 1921 textbook Psychology: A study of mental life, describes euphoria as an organic state, the opposite of fatigue, "means about the same as feeling good."In 1940 The Journal of Psychology defined euphoria as a "state of general well being... and pleasantly toned feeling."
A decade finding ordinary feelings of well being difficult to evaluate, American addiction researcher Harris Isbell redefined euphoria as behavioral changes and objective signs typical of morphine. However, in 1957 British pharmacologist D. A. Cahal did not regard opioid euphoria as medically undesirable but an effect which "enhance the value of a major analgesic." The 1977 edition of A Concise Encyclopaedia of Psychiatry called euphoria "a mood of contentment and well-being," with pathologic associations when used in a psychiatric context. As a sign of cerebral disease, it was described as bland and out of context, representing an inability to experience negative emotion. In the 21st century, euphoria is defined as a state of great happiness, well-being and excitement, which may be normal, or abnormal and inappropriate when associated with psychoactive drugs, manic states, or brain disease or injury. Hedonic hotspots – i.e. the pleasure centers of the brain – are functionally linked. Activation of one hotspot results in the recruitment of the others.
Inhibition of one hotspot results in the blunting of the effects of activating another hotspot. Therefore, the simultaneous activation of every hedonic hotspot within the reward system is believed to be necessary for generating the sensation of euphoria. Many different types of stimuli can induce euphoria, including psychoactive drugs, natural rewards, social activities. Affective disorders such as unipolar mania or bipolar disorder can involve euphoria as a symptom. Continuous physical exercise aerobic exercise, can induce a state of euphoria. Exercise is known to affect dopamine signaling in the nucleus accumbens, producing euphoria as a result, through increased biosynthesis of three particular neurochemicals: anandamide, β-endorphin, phenethylamine. Euphoria can occur as a result of dancing to music, music-making, listening to arousing music. Neuroimaging studies have demonstrated that the reward system plays a central role in mediating music-induced pleasure. Pleasurable arousing music increases dopamine neurotransmission in the dopaminergic pathways that project to the striatum.
5% of the population experiences a phenomenon termed "musical anhedonia", in which individuals do not experience pleasure from listening to arousing music despite having the ability to perceive the intended emotion, conveyed in passages of music. The various stages of copulation may be described as inducing euphoria in some people. Various analysts have described either the entire act of copulation, the moments leading to orgasm, or the orgasm itself as the pinnacle of human pleasure or euphoria. A euphoriant is a type of psychoactive drug. Most euphoriants are addictive drugs due to their reinforcing properties and ability to activate the brain's reward system. Dopaminergic stimulants like amphetamine, cocaine, MDMA, methylphenidate are euphoriants. Nicotine is a parasympathetic stimulant. Chewing areca nut (se