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Classical models of unemployment occurs when wages are too high for employers to be willing to hire more workers. Consistent with classical unemployment, frictional unemployment occurs when appropriate job vacancies exist for a worker, but the length of time needed to search for and find the job leads to a period of un...
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Structural unemployment covers a variety of possible causes of unemployment including a mismatch between workers' skills and the skills required for open jobs. Large amounts of structural unemployment can occur when an economy is transitioning industries and workers find their previous set of skills are no longer in de...
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While some types of unemployment may occur regardless of the condition of the economy, cyclical unemployment occurs when growth stagnates. Okun's law represents the empirical relationship between unemployment and economic growth. The original version of Okun's law states that a 3% increase in output would lead to a 1% ...
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Money is a "means of final payment" for goods in most price system economies, and is the unit of account in which prices are typically stated. Money has general acceptability, relative consistency in value, divisibility, durability, portability, elasticity in supply, and longevity with mass public confidence. It includ...
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As a medium of exchange, money facilitates trade. It is essentially a measure of value and more importantly, a store of value being a basis for credit creation. Its economic function can be contrasted with barter (non-monetary exchange). Given a diverse array of produced goods and specialized producers, barter may enta...
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At the level of an economy, theory and evidence are consistent with a positive relationship running from the total money supply to the nominal value of total output and to the general price level. For this reason, management of the money supply is a key aspect of monetary policy.
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Governments implement fiscal policy to influence macroeconomic conditions by adjusting spending and taxation policies to alter aggregate demand. When aggregate demand falls below the potential output of the economy, there is an output gap where some productive capacity is left unemployed. Governments increase spending ...
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For example, unemployed home builders can be hired to expand highways. Tax cuts allow consumers to increase their spending, which boosts aggregate demand. Both tax cuts and spending have multiplier effects where the initial increase in demand from the policy percolates through the economy and generates additional econo...
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The effects of fiscal policy can be limited by crowding out. When there is no output gap, the economy is producing at full capacity and there are no excess productive resources. If the government increases spending in this situation, the government uses resources that otherwise would have been used by the private secto...
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Sceptics of fiscal policy also make the argument of Ricardian equivalence. They argue that an increase in debt will have to be paid for with future tax increases, which will cause people to reduce their consumption and save money to pay for the future tax increase. Under Ricardian equivalence, any boost in demand from ...
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Public economics is the field of economics that deals with economic activities of a public sector, usually government. The subject addresses such matters as tax incidence (who really pays a particular tax), cost-benefit analysis of government programmes, effects on economic efficiency and income distribution of differe...
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Much of economics is positive, seeking to describe and predict economic phenomena. Normative economics seeks to identify what economies "ought" to be like.
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Welfare economics is a normative branch of economics that uses microeconomic techniques to simultaneously determine the allocative efficiency within an economy and the income distribution associated with it. It attempts to measure social welfare by examining the economic activities of the individuals that comprise soci...
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International trade studies determinants of goods-and-services flows across international boundaries. It also concerns the size and distribution of gains from trade. Policy applications include estimating the effects of changing tariff rates and trade quotas. International finance is a macroeconomic field which examine...
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Labor economics seeks to understand the functioning and dynamics of the markets for wage labor. Labor markets function through the interaction of workers and employers. Labor economics looks at the suppliers of labor services (workers), the demands of labor services (employers), and attempts to understand the resulting...
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Development economics examines economic aspects of the economic development process in relatively low-income countries focusing on structural change, poverty, and economic growth. Approaches in development economics frequently incorporate social and political factors.
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Economics has historically been subject to criticism that it relies on unrealistic, unverifiable, or highly simplified assumptions, in some cases because these assumptions simplify the proofs of desired conclusions. For example, the economist Friedrich Hayek claimed that economics (at least historically) used a scienti...
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Prominent historical mainstream economists such as Keynes and Joskow observed that much of the economics of their time was conceptual rather than quantitative, and difficult to model and formalize quantitatively. In a discussion on oligopoly research, Paul Joskow pointed out in 1975 that in practice, serious students o...
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Issues like central bank independence, central bank policies and rhetoric in central bank governors discourse or the premises of macroeconomic policies (monetary and fiscal policy) of the state are a focus of contention and criticism.
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In the 1990s, feminist critiques of neoclassical economic models gained prominence, leading to the formation of feminist economics. Feminist economists call attention to the social construction of economics and claims to highlight the ways in which its models and methods reflect masculine preferences. Primary criticism...
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Economics has been derogatorily dubbed "the dismal science", first coined by the Victorian historian Thomas Carlyle in the 19th century. It is often stated that Carlyle gave it this nickname as a response to the work of Thomas Robert Malthus, who predicted widespread starvation resulting from projections that populatio...
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Economics is one social science among several and has fields bordering on other areas, including economic geography, economic history, public choice, energy economics, , family economics and institutional economics.
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Law and economics, or economic analysis of law, is an approach to legal theory that applies methods of economics to law. It includes the use of economic concepts to explain the effects of legal rules, to assess which legal rules are economically efficient, and to predict what the legal rules will be. A seminal article ...
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Political economy is the interdisciplinary study that combines economics, law, and political science in explaining how political institutions, the political environment, and the economic system (capitalist, socialist, mixed) influence each other. It studies questions such as how monopoly, rent-seeking behaviour, and ex...
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Energy economics is a broad scientific subject area which includes topics related to energy supply and energy demand. Georgescu-Roegen reintroduced the concept of entropy in relation to economics and energy from thermodynamics, as distinguished from what he viewed as the mechanistic foundation of neoclassical economics...
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The sociological subfield of economic sociology arose, primarily through the work of Émile Durkheim, Max Weber and Georg Simmel, as an approach to analysing the effects of economic phenomena in relation to the overarching social paradigm (i.e. modernity). Classic works include Max Weber's "The Protestant Ethic and the ...
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Gary Becker in 1974 presented an economic theory of social interactions, whose applications included the family, charity, merit goods and multiperson interactions, and envy and hatred.
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The professionalization of economics, reflected in the growth of graduate programmes on the subject, has been described as "the main change in economics since around 1900". Most major universities and many colleges have a major, school, or department in which academic degrees are awarded in the subject, whether in the ...
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In the private sector, professional economists are employed as consultants and in industry, including banking and finance. Economists also work for various government departments and agencies, for example, the national treasury, central bank or National Bureau of Statistics. See Economic analyst.
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There are dozens of prizes awarded to economists each year for outstanding intellectual contributions to the field, the most prominent of which is the Nobel Memorial Prize in Economic Sciences, though it is not a Nobel Prize.
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Contemporary economics uses mathematics. Economists draw on the tools of calculus, linear algebra, statistics, game theory, and computer science. Professional economists are expected to be familiar with these tools, while a minority specialize in econometrics and mathematical methods.
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Harriet Martineau (1802-1876) was a widely-read populariser of classical economic thought. Mary Paley Marshall (1850-1944), the first women lecturer at a British economics faculty, wrote "The Economics of Industry" with her husband Alfred Marshall. Joan Robinson (1903-1983) was an important post-Keynesian economist. Th...
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Women's authorship share in prominent economic journals reduced from 1940 to the 1970s, but has subsequently risen, with different patterns of gendered coauthorship. Women remain globally under-represented in the profession (19% of authors in the RePEc database in 2018), with national variation.
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Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine to the adenosine A receptor, which enhances release of the neurotransmitter acetylc...
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Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, and is chemically related to the adenine and guanine bases of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is found in the seeds, fruits, nuts, or leaves of a number of plants native to Africa, East Asia and South America, and help...
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Caffeine has both positive and negative health effects. It can treat and prevent the premature infant breathing disorders bronchopulmonary dysplasia of prematurity and apnea of prematurity. Caffeine citrate is on the WHO Model List of Essential Medicines. It may confer a modest protective effect against some diseases, ...
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Caffeine is classified by the US Food and Drug Administration as generally recognized as safe. Toxic doses, over 10 grams per day for an adult, are much higher than the typical dose of under 500 milligrams per day. The European Food Safety Authority reported that up to 400 mg of caffeine per day (around 5.7 mg/kg of bo...
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Caffeine is a central nervous system stimulant that may reduce fatigue and drowsiness. At normal doses, caffeine has variable effects on learning and memory, but it generally improves reaction time, wakefulness, concentration, and motor coordination. The amount of caffeine needed to produce these effects varies from pe...
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Caffeine can delay or prevent sleep and improves task performance during sleep deprivation. Shift workers who use caffeine make fewer mistakes that could result from drowsiness.
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A systematic review and meta-analysis from 2014 found that concurrent caffeine and -theanine use has synergistic psychoactive effects that promote alertness, attention, and task switching; these effects are most pronounced during the first hour post-dose.
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Caffeine is a proven ergogenic aid in humans. Caffeine improves athletic performance in aerobic (especially endurance sports) and anaerobic conditions. Moderate doses of caffeine (around 5 mg/kg) can improve sprint performance, cycling and running time trial performance, endurance (i.e., it delays the onset of muscle f...
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Caffeine improves muscular strength and power, and may enhance muscular endurance. Caffeine also enhances performance on anaerobic tests. Caffeine consumption before constant load exercise is associated with reduced perceived exertion. While this effect is not present during exercise-to-exhaustion exercise, performance...
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For the general population of healthy adults, Health Canada advises a daily intake of no more than 400 mg. This limit was found to be safe by a 2017 systematic review on caffeine toxicology.
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In healthy children, moderate caffeine intake under 400 mg produces effects that are "modest and typically innocuous". As early as 6 months old, infants can metabolize caffeine at the same rate as that of adults. Higher doses of caffeine (>400 mg) can cause physiological, psychological and behavioral harm, particularly...
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Health Canada has not developed advice for adolescents because of insufficient data. However, they suggest that daily caffeine intake for this age group be no more than 2.5 mg/kg body weight. This is because the maximum adult caffeine dose may not be appropriate for light-weight adolescents or for younger adolescents w...
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The metabolism of caffeine is reduced in pregnancy, especially in the third trimester, and the half-life of caffeine during pregnancy can be increased up to 15 hours (as compared to 2.5 to 4.5 hours in non-pregnant adults). Current evidence regarding the effects of caffeine on pregnancy and for breastfeeding are inconc...
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The UK Food Standards Agency has recommended that pregnant women should limit their caffeine intake, out of prudence, to less than 200 mg of caffeine a day – the equivalent of two cups of instant coffee, or one and a half to two cups of fresh coffee. The American Congress of Obstetricians and Gynecologists (ACOG) concl...
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There are conflicting reports in the scientific literature about caffeine use during pregnancy. A 2011 review found that caffeine during pregnancy does not appear to increase the risk of congenital malformations, miscarriage or growth retardation even when consumed in moderate to high amounts. Other reviews, however, c...
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Caffeine in coffee and other caffeinated drinks can affect gastrointestinal motility and gastric acid secretion. In postmenopausal women, high caffeine consumption can accelerate bone loss.
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Acute ingestion of caffeine in large doses (at least 250–300 mg, equivalent to the amount found in 2–3 cups of coffee or 5–8 cups of tea) results in a short-term stimulation of urine output in individuals who have been deprived of caffeine for a period of days or weeks. This increase is due to both a diuresis (increase...
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Minor undesired symptoms from caffeine ingestion not sufficiently severe to warrant a psychiatric diagnosis are common and include mild anxiety, jitteriness, insomnia, increased sleep latency, and reduced coordination. Caffeine can have negative effects on anxiety disorders. According to a 2011 literature review, caffe...
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In moderate doses, caffeine has been associated with reduced symptoms of depression and lower suicide risk. Two reviews indicate that increased consumption of coffee and caffeine may reduce the risk of depression.
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Some textbooks state that caffeine is a mild euphoriant, while others state that it is not a euphoriant.
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Caffeine-induced anxiety disorder is a subclass of the DSM-5 diagnosis of substance/medication-induced anxiety disorder.
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Whether caffeine can result in an addictive disorder depends on how addiction is defined. Compulsive caffeine consumption under any circumstances has not been observed, and caffeine is therefore not generally considered addictive. However, some diagnostic models, such as the and ICD-10, include a classification of caff...
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Caffeine does not appear to be a reinforcing stimulus, and some degree of aversion may actually occur, with people preferring placebo over caffeine in a study on drug abuse liability published in an NIDA research monograph. Some state that research does not provide support for an underlying biochemical mechanism for ca...
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"Caffeine addiction" was added to the ICDM-9 and ICD-10. However, its addition was contested with claims that this diagnostic model of caffeine addiction is not supported by evidence. The American Psychiatric Association's does not include the diagnosis of a "caffeine addiction" but proposes criteria for the disorder f...
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Withdrawal can cause mild to clinically significant distress or impairment in daily functioning. The frequency at which this occurs is self-reported at 11%, but in lab tests only half of the people who report withdrawal actually experience it, casting doubt on many claims of dependence. Mild physical dependence and wit...
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The ICD-11 includes caffeine dependence as a distinct diagnostic category, which closely mirrors the DSM-5's proposed set of criteria for "caffeine-use disorder".  Caffeine use disorder refers to dependence on caffeine characterized by failure to control caffeine consumption despite negative physiological consequences....
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Tolerance to the effects of caffeine occurs for caffeine-induced elevations in blood pressure and the subjective feelings of nervousness. Sensitization, the process whereby effects become more prominent with use, occurs for positive effects such as feelings of alertness and wellbeing. Tolerance varies for daily, regula...
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A protective effect of caffeine against Alzheimer's disease and dementia is possible but the evidence is inconclusive. It may protect people from liver cirrhosis. Caffeine may lessen the severity of acute mountain sickness if taken a few hours prior to attaining a high altitude. One meta analysis has found that caffein...
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Caffeine increases intraocular pressure in those with glaucoma but does not appear to affect normal individuals.
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The DSM-5 also includes other caffeine-induced disorders consisting of caffeine-induced anxiety disorder, caffeine-induced sleep disorder and unspecified caffeine-related disorders. The first two disorders are classified under "Anxiety Disorder" and "Sleep-Wake Disorder" because they share similar characteristics. Othe...
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Consumption of per day is associated with a condition known as "<dfn>caffeinism</dfn>." Caffeinism usually combines caffeine dependency with a wide range of unpleasant symptoms including nervousness, irritability, restlessness, insomnia, headaches, and palpitations after caffeine use.
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Caffeine overdose can result in a state of central nervous system overstimulation known as caffeine intoxication, a clinically significant temporary condition that develops during, or shortly after, the consumption of caffeine. This syndrome typically occurs only after ingestion of large amounts of caffeine, well over ...
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According to the International Classification of Diseases (ICD-11), cases of very high caffeine intake (e.g. > 5 g) may result in caffeine intoxication with symptoms including mania, depression, lapses in judgment, disorientation, disinhibition, delusions, hallucinations or psychosis, and rhabdomyolysis.
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High caffeine consumption in energy drinks (at least 1 liter or 320 mg of caffeine) was associated with short-term cardiovascular side effects including hypertension, prolonged QT interval, and heart palpitations. These cardiovascular side effects were not seen with smaller amounts of caffeine consumption in energy dri...
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As of 2007 there is no known antidote or reversal agent for caffeine intoxication. Treatment of mild caffeine intoxication is directed toward symptom relief; severe intoxication may require peritoneal dialysis, hemodialysis, or hemofiltration. Intralipid infusion therapy is indicated in cases of imminent risk of cardia...
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Death from caffeine ingestion appears to be rare, and most commonly caused by an intentional overdose of medications. In 2016, 3702 caffeine-related exposures were reported to Poison Control Centers in the United States, of which 846 required treatment at a medical facility, and 16 had a major outcome; and several caff...
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Caffeine is a substrate for CYP1A2, and interacts with many substances through this and other mechanisms.
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According to DSST, alcohol provides a reduction in performance and caffeine has a significant improvement in performance. When alcohol and caffeine are consumed jointly, the effects produced by caffeine are affected, but the alcohol effects remain the same. For example, when additional caffeine is added, the drug effec...
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Smoking tobacco increases caffeine clearance by 56%. Cigarette smoking induces the cytochrome P450 1A2 enzyme that breaks down caffeine, which may lead to increased caffeine tolerance and coffee consumption for regular smokers.
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Birth control pills can extend the half-life of caffeine, requiring greater attention to caffeine consumption.
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Caffeine sometimes increases the effectiveness of some medications, such as those for headaches. Caffeine was determined to increase the potency of some over-the-counter analgesic medications by 40%.
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The pharmacological effects of adenosine may be blunted in individuals taking large quantities of methylxanthines like caffeine. Some other examples of methylxanthines include the medications theophylline and aminophylline, which are prescribed to relieve symptoms of asthma or COPD.
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In the absence of caffeine and when a person is awake and alert, little adenosine is present in CNS neurons. With a continued wakeful state, over time adenosine accumulates in the neuronal synapse, in turn binding to and activating adenosine receptors found on certain CNS neurons; when activated, these receptors produc...
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Caffeine is an antagonist of adenosine A receptors, and knockout mouse studies have specifically implicated antagonism of the A receptor as responsible for the wakefulness-promoting effects of caffeine. Antagonism of A receptors in the ventrolateral preoptic area (VLPO) reduces inhibitory GABA neurotransmission to the ...
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Antagonism of adenosine receptors by caffeine also stimulates the medullary vagal, vasomotor, and respiratory centers, which increases respiratory rate, reduces heart rate, and constricts blood vessels. Adenosine receptor antagonism also promotes neurotransmitter release (e.g., monoamines and acetylcholine), which endo...
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Because caffeine is both water- and lipid-soluble, it readily crosses the blood–brain barrier that separates the bloodstream from the interior of the brain. Once in the brain, the principal mode of action is as a nonselective antagonist of adenosine receptors (in other words, an agent that reduces the effects of adenos...
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In addition to its activity at adenosine receptors, caffeine is an inositol trisphosphate receptor 1 antagonist and a voltage-independent activator of the ryanodine receptors (RYR1, RYR2, and RYR3). It is also a competitive antagonist of the ionotropic glycine receptor.
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While caffeine does not directly bind to any dopamine receptors, it influences the binding activity of dopamine at its receptors in the striatum by binding to adenosine receptors that have formed GPCR heteromers with dopamine receptors, specifically the A–D receptor heterodimer (this is a receptor complex with 1 adenos...
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Caffeine also causes the release of dopamine in the dorsal striatum and nucleus accumbens core (a substructure within the ventral striatum), but not the nucleus accumbens shell, by antagonizing A receptors in the axon terminal of dopamine neurons and A–A heterodimers (a receptor complex composed of 1 adenosine A recept...
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Caffeine, like other xanthines, also acts as a phosphodiesterase inhibitor. As a competitive nonselective phosphodiesterase inhibitor, caffeine raises intracellular cyclic AMP, activates protein kinase A, inhibits TNF-alpha and leukotriene synthesis, and reduces inflammation and innate immunity. Caffeine also affects t...
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Caffeine from coffee or other beverages is absorbed by the small intestine within 45 minutes of ingestion and distributed throughout all bodily tissues. Peak blood concentration is reached within 1–2 hours. It is eliminated by first-order kinetics. Caffeine can also be absorbed rectally, evidenced by suppositories of e...
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Caffeine's biological half-life – the time required for the body to eliminate one-half of a dose – varies widely among individuals according to factors such as pregnancy, other drugs, liver enzyme function level (needed for caffeine metabolism) and age. In healthy adults, caffeine's half-life is between 3 and 7 hours. ...
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Caffeine is metabolized in the liver by the cytochrome P450 oxidase enzyme system, in particular, by the CYP1A2 isozyme, into three dimethylxanthines, each of which has its own effects on the body:
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1,3,7-Trimethyluric acid is a minor caffeine metabolite. 7-Methylxanthine is also a metabolite of caffeine. Each of the above metabolites is further metabolized and then excreted in the urine. Caffeine can accumulate in individuals with severe liver disease, increasing its half-life.
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A 2011 review found that increased caffeine intake was associated with a variation in two genes that increase the rate of caffeine catabolism. Subjects who had this mutation on both chromosomes consumed 40 mg more caffeine per day than others. This is presumably due to the need for a higher intake to achieve a comparab...
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Pure anhydrous caffeine is a bitter-tasting, white, odorless powder with a melting point of 235–238 °C. Caffeine is moderately soluble in water at room temperature (2 g/100 mL), but very soluble in boiling water (66 g/100 mL). It is also moderately soluble in ethanol (1.5 g/100 mL). It is weakly basic (pK of conjugate ...
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The xanthine core of caffeine contains two fused rings, a pyrimidinedione and imidazole. The pyrimidinedione in turn contains two amide functional groups that exist predominantly in a zwitterionic resonance the location from which the nitrogen atoms are double bonded to their adjacent amide carbons atoms. Hence all six...
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Commercial supplies of caffeine are not usually manufactured synthetically because the chemical is readily available as a byproduct of decaffeination.
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Extraction of caffeine from coffee, to produce caffeine and decaffeinated coffee, can be performed using a number of solvents. Following are main methods:
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"Decaffeinated" coffees do in fact contain caffeine in many cases – some commercially available decaffeinated coffee products contain considerable levels. One study found that decaffeinated coffee contained 10 mg of caffeine per cup, compared to approximately 85 mg of caffeine per cup for regular coffee.
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Caffeine can be quantified in blood, plasma, or serum to monitor therapy in neonates, confirm a diagnosis of poisoning, or facilitate a medicolegal death investigation. Plasma caffeine levels are usually in the range of 2–10 mg/L in coffee drinkers, 12–36 mg/L in neonates receiving treatment for apnea, and 40–400 mg/L ...
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Some analog substances have been created which mimic caffeine's properties with either function or structure or both. Of the latter group are the xanthines DMPX and 8-chlorotheophylline, which is an ingredient in dramamine. Members of a class of nitrogen substituted xanthines are often proposed as potential alternative...
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Caffeine, as do other alkaloids such as cinchonine, quinine or strychnine, precipitates polyphenols and tannins. This property can be used in a quantitation method.
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Around thirty plant species are known to contain caffeine. Common sources are the "beans" (seeds) of the two cultivated coffee plants, "Coffea arabica" and "Coffea canephora" (the quantity varies, but 1.3% is a typical value); and of the cocoa plant, "Theobroma cacao"; the leaves of the tea plant; and kola nuts. Other ...
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Caffeine in plants acts as a natural pesticide: it can paralyze and kill predator insects feeding on the plant. High caffeine levels are found in coffee seedlings when they are developing foliage and lack mechanical protection. In addition, high caffeine levels are found in the surrounding soil of coffee seedlings, whi...
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The differing perceptions in the effects of ingesting beverages made from various plants containing caffeine could be explained by the fact that these beverages also contain varying mixtures of other methylxanthine alkaloids, including the cardiac stimulants theophylline and theobromine, and polyphenols that can form i...
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Products containing caffeine include coffee, tea, soft drinks ("colas"), energy drinks, other beverages, chocolate, caffeine tablets, other oral products, and inhalation products. According to a 2020 study in the United States, coffee is the major source of caffeine intake in middle-aged adults, while soft drinks and t...
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