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Received: 26 November 2019 Revised: 10 January 2020 Accepted: 19 January 2020 DOI: 10.1111/obr.13005 PEDIATRICS/PHYSIOLOGY Adipokines: A gear shift in puberty Desirée Nieuwenhuis | Natàlia Pujol-Gualdo Amanda J. Kiliaan Department of Anatomy, Radboud university medical center, Donders Institute for Brain, Cognition and Behaviour, Preclinical Imaging Center PRIME, Nijmegen, The Netherlands Correspondence Amanda J. Kiliaan, PhD, Associate Professor, Department of Anatomy, Donders Institute for Brain, Cognition, and Behaviour, Preclinical Imaging Center PRIME, Radboud university medical center, 6500 HB Nijmegen, Geert Grooteplein 21N 6525 EZ Nijmegen, The Netherlands. Email: amanda.kiliaan@radboudumc.nl Funding information Europees Fonds voor Regionale Ontwikkeling (EFRO), Grant/Award Number: BriteN 2016 1 | INTRODUCTION The prevalence of obesity in adolescents and children is increasing in | Ilse A.C. Arnoldussen | Summary In this review, we discuss the role of adipokines in the onset of puberty in children with obesity during adrenarche and gonadarche and provide a clear and detailed overview of the biological processes of two major players, leptin and adiponectin. Adipokines, especially leptin and adiponectin, seem to induce an early onset of puberty in girls and boys with obesity by affecting the hypothalamic-pituitary- gonadal (HPG) axis. Moreover, adipokines and their receptors are expressed in the gonads, suggesting a role in sexual maturation and reproduction. All in all, adipokines may be a clue in understanding mechanisms underlying the onset of puberty in child- hood obesity and puberty onset variability. KEYWORDS adipokines, obesity, puberty 1,2 the age of 5 years were overweight or were with obesity in 2016, and 3 Obesity is defined by an excessive accumulation of white adipose tissue (WAT), and it is often indicated by a body mass index (BMI) 4 above 30. Two main types of adipose tissue were described: WAT and brown adipose tissue (BAT), which differ in morphology and func- 5-7 Ilse A.C. Arnoldussen and Amanda J. Kiliaan contributed equally to this work. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2020 The Authors. Obesity Reviews published by John Wiley & Sons Ltd on behalf of World Obesity Federation Obesity Reviews. 2020;21:e13005. wileyonlinelibrary.com/journal/obr 1 of 10 https://doi.org/10.1111/obr.13005 alarming rates. Specifically, worldwide, 41 million children below this number is expected to increase to 70 million in 2025. obesity is associated with various severe health complications, includ- ing increased risk of diabetes mellitus type 2, hypertension, heart dis- eases, and disturbances in sex hormone levels. 5,6 and mitochondria and plays a role in thermogenesis. Adipocytes in tion. BAT consists of adipocytes containing multiple lipid droplets WAT contain only a few mitochondria and a single lipid droplet. Adipose tissue has several functions including the storage of energy, thermogenesis, and the production and secretion of adipokines Generally, two physiological processes, adrenarche and gonadarche, 11,24 Childhood 5,7,8 a key role in puberty onset. Puberty is known as a period through which the body changes physically, being a physiological process resulting in the maturation of children, i.e. they develop sexual characteristics and obtain reproduc- 9,11 Adipokines are involved in a number of physiological processes including blood pressure, metabo- lism, glucose, and vascular homeostasis and may play amongst others 8-10 (hormones, cytokines, and peptides). tive functions. between obesity and puberty,2,12-23 the biological mechanisms under- lying obesity and puberty onset remain unclear. Hereafter, we review in detail the role of adipokines in the onset of puberty in childhood obesity. Although many studies have shown associations 2 | INITIATION OF PUBERTY PHYSIOLOGICAL PROCESSES IN THE interact to regulate the onset of puberty. During adrenarche, the adrenal cortex secretes steroid hormones (including 2 of 10 NIEUWENHUIS ET AL. androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate (DHEAS), androstenedione, and cortisol), insulin-like growth factor, and growth hormone, which contribute to the pubertal insights on new genetic loci (e.g. melanocortin-4 receptor, mitochon- drial carrier 2, and mitogen-activated protein kinase 13) and on sev- eral pathways that regulate the timing of puberty; however, it partly 34 9,24,25 Both adrenarche and gonadarche are involved in the development growth spurt, body odor, skin oiliness, and skeletal maturation. explains puberty timing variation. Thereby, defining the role of 25 adipokines is of importance in elucidating the variability in puberty as the expression of adipokines is sex-specific and is altered with body composition, adiposity, and during growth spurts. Moreover, adipokines and their receptors are expressed in gonads and several brain regions suggesting involvement in the onset of puberty and sex- ual maturation. Lastly, adipokines interfere in processes regulating timing and duration of puberty, for instance in the HPA and HPG axes which are both key players during adrenarche and gonadarche. Involvement of adipokines in the onset of puberty and specifically in individuals with obesity will be further reviewed in the next 2,24 3 | Puberty onset in girls is assessed using different markers, such as thelarche (breast development), menarche (the start of of pubic hair. pituitary-gonadal (HPG) axis is activated,2,26 and several hormones have been identified to participate in the activation of the HPG axis During gonadarche (Figure 1), the hypothalamic- 2,27 Kisspeptin, neurokinin B, and dynorphin are released by specialized including kisspeptin, neurokinin B, dynorphin, leptin, and ghrelin. 28 key regulator of the pulsatile secretion of gonadotropin releasing neurons, the KNDy neurons in the hypothalamus. Kisspeptin is a 29,30 B stimulates, and dynorphin inhibits the release of kisspeptin, which hormone (GnRH) from the hypothalamus. In addition, neurokinin implies that both coordinate a pulsatile release of kisspeptin. 31 Sub- sections. sequently, the activated HPG axis induces the pituitary gland to secrete luteinising hormone (LH) and follicle stimulating hormone (FSH). As a result, gametogenesis occurs, and the gonads will release sex hormones. Consequently, secondary sex characteristics develop including breast development in girls and an increased testicular vol- 2,26,32 is possibly due to differences in levels of body fat, hypothalamic-pitui- THE ONSET OF PUBERTY IN GIRLS ume in boys. The age at puberty onset varies greatly among individuals, which 19 35 menstruation), and pubic hair development. 33 genome-wide association studies have provided important new tary-adrenal (HPA) axis activity, and genetic background. Recent The average age of However, this age differs between cultures and ethnicities, and since 1980, age at menarche is girls at start of menarche is 12.4 years. 36 significantly decreasing. 36-39 F I G U R E 1 Hormonal regulation in the initiation of puberty in boys and girls. The secretion of kisspeptin, neurokinin B, and dynorphin from KNDy neurons initiate the release of gonadotropin releasing hormone (GnRH) from the hypothalamus. This activates the pituitary gland to produce and secrete luteinising hormone (LH) and follicle stimulating hormone (FSH), which in turn stimulate the gonads to produce estrogen and testosterone in girls and boys, respectively 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License NIEUWENHUIS ET AL. 3 of 10 T A B L E 1 Summary of included studies Authors Year Country Study Design Primary Outcome Sex Sample Size (n) Age (y) Data Collection Lian et al21 2019 China Cross-sectional Puberty starts earlier in Chinese Han girls with obesity compared with Chinese Han girls with normal weight. Girls 2996 9-19 2012 and 2013 Biro et al12 Lazzeri et al20 2018 USA 2018 Italy Longitudinal Cross-sectional Body mass index had a greater effect on age at menarche than did race and ethnicity. Girls 946 6-16 2004-2014 Li et al23 2018 China Longitudinal For both, boys and girls, a higher BMI (ie, overweight and obese) is associated with earlier onset of puberty Girls Girls Boys Girls 542 Deng et al22 Flom et al15 2017 China Cross-sectional Increased BMI is associated with early timing spermarche and menarche. Boys Girls Girls 1278258 9-15 2005-2012 He et al24 Holmgren et al17 2017 China 2017 Sweden Cross-sectional Longitudinal Onset of puberty is not related to obesity in boys. Boys Boys Girls Girls 782 7-17 972 929 5839 Kelly et al19 2017 UK 2016 Brazil 2016 USA Longitudinal prospective cohort Higher BMI in girls is associated with the onset of menstruation at an earlier age. 11 10-18 11-17 Barcellos Gemelli et al25 Cross-sectional Longitudinal Excess weight is associated with early age of menarche. Girls 727 2014 2003-2009 Glass et al16 Lee et al26 In girls, but not in boys, greater adiposity is associated with the earlier onset of puberty. Boys Girls 135 Cabrera et al27 Leonibus et al14 2014 USA 2013 Italy Cross-sectional Longitudinal Thelarche occurred earlier than recently reported, while age of menarche remained unchanged. Girls 610 3-17.9 2007 2005-2012 Currie et al13 2012 Europe, USA, Canada Cross-sectional Overweight/obesity during childhood predicts the early onset of puberty in girls. Girls 20410 11, 13, 15 2005-2006 2017 USA Prospective birth cohort Overweight/obese status at the age of 7 ye was associated with increased risk of early menarche 788 From birth to menarche occurred Pregnancies 1959-1966 2016 USA Cross-sectional Boys with overweight enter puberty earlier compared with boys with normal weight or obesity, while puberty starts later in boys with obesity compared with boys with normal weight and overweight. Boys 3872 6-16 2005-2010 Overweight during childhood shows a relation with the early onset of puberty in girls. 6535 4259 695 11 15 5.8-12.2 2009/2010 2013/2014 2014-2017 Higher BMI during childhood is associated with early puberty. 2008 and 2009 2000-2002 Obesity during childhood is related to the earlier onset of puberty. Boys Girls 84 123 71 (Continues) 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 4 of 10 NIEUWENHUIS ET AL. 3.1 | Fat storage For the initiation of puberty, the timing of stimulation and/or inhibi- tion of different hormones is important, and additionally, a certain amount and distribution of body fat is needed in order to start menar- che, which emphasizes the importance of body fat. From an evolution- ary point of view, body fat increases in mammalian females during puberty onset, and it highlights the need to guarantee a healthy preg- 40 women with anorexia nervosa. particularly body fat localized predominantly on the gluteofemoral fat depots, is profoundly associated with start of menarche, more than nancy, offspring, and maternal survival. fat, sex-hormones, and neuroendocrine alterations can evolve in men- strual dysfunction, for instance, in women with severe obesity or in 41-43 44-46 to gluteofemoral fat depots suggesting that leptin may convey infor- amount of total body fat. mation on body fat distribution to the hypothalamus during puberty. An improper level of body Importantly, body fat distribution, Blood leptin levels are strongly related 45 3.2 | HPG axis The HPG axis is activated by the release of kisspeptin resulting in the release of GnRH from the hypothalamus, and LH and FSH from the pituitary gland. In girls, FSH is involved in the development of the folli- cles in the ovaries, and it promotes the secretion of estrogen. LH stim- ulates the production of androgen hormones and induces ovulation 48 9,47 the release of kisspeptin and neurokinin B, and kisspeptin thereby (Figure 1). The secretion of estrogen has an inhibitory effect on inhibits the GnRH release from the hypothalamus. pattern of GnRH is important for the regulation of the menstrual cycle. This roughly 28-day-cycle comprises several phases, including the follicular phase and luteal phase. During the follicular phase, increasing levels of FSH stimulate the maturation of follicles and the production of estrogen from the ovaries. This in turn inhibits the release of FSH from the pituitary gland. A high level of estrogen will induce the production of LH by the pituitary gland, resulting in ovula- tion. The matured follicle secretes progesterone thereby inhibiting the release of GnRH. When the corpus luteum is demolished, there is less 48 3.3 | Adipokines According to results from studies reported in Table 1, girls with obe- sity enter puberty earlier compared with girls with normal higher leptin concentrations inhibit the intake of food and increases inhibition of GnRH. As a consequence, the cycle will start again. whole process, starting from the activated HPG axis, results in the development of the secondary sex characteristics in girls including 9,47 thelarche and menarche. 13,14,16-23,49-51 weight. these girls might be found in the secretion of adipokines. For instance, leptin is positively associated with the amount of body fat. Generally, energy expenditure. 9,52-54 An explanation for the early onset of puberty in The expression This TABLE 1 (Continued) Authors Year Country Study Design Primary Outcome Sample Sex Size (n) Age (y) Data Collection Herman-Giddens et al28 2012 USA Cross-sectional Observed mean ages of beginning genital and pubic hair growth and early testicular volumes were earlier than in past studies, depending on the characteristic and race/ethnicity. Boys 4131 6-16 2005-2010 Sorensen et al29 Aksglaede et al30 2010 2009 Denmark Denmark Cross-sectional/longitudinal Longitudinal Puberty onset at earlier ages was associated with an increased BMI in boys. Boys 1528 5.8-19.9 1991-1993/2006-2008 1930-1969 Juul et al31 Ribeiro et al32 2007 2006 Denmark Portugal Retrospective cohort Cross-sectional Higher BMI is associated with early voice break. 11-15 10-15 1990-1999 Kaplowitz et al18 Abbreviation: BMI, body mass USA Cross-sectional The early onset of puberty in Caucasian girls is likely related to an increased BMI. 5-12 1992-1993 2001 index. The higher BMI in boys and girls at 7 y of age, the earlier they enter puberty. Boys 21 612 Girls 135 223 Boys 463 Boys 382 Girls 437 Girls 10 750 Early sexual maturation in boys and girls is associated with overweight. 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License NIEUWENHUIS ET AL. 5 of 10 Leptin may possibly play a role in adrenarche as its plasma level increases with higher levels of body fat and as it can modulate both girls. 33 ing adrenarche. In coherence, in children with obesity, the androgen These findings suggested that lower reproductive status was associated with higher total adiponectin concentrations and that a higher reproductive status was related to higher HMW adiponectin the HPA and HPG axes. These axes are functionally integrated dur- DHEAS was positively associated with leptin levels. Nevertheless, concentrations in girls. In addition, individuals with obesity often another study showed that enhanced adrenal androgen secretion in girls with premature adrenarche was not explained by leptin or BMI 55 ated with androgen levels in girls ; however, it was not related to levels. and IL-6. TNF-α alters, and IL-6 inhibits the expression of 56 8 In addition, the adipokine adiponectin was negatively associ- 57 differences of adiponectin seem to develop during the progression of 56 adiponectin (Figure 2). Thereby, a low level of total adiponectin and/or high levels of inflammatory cytokines in individuals with obe- sity can promote the onset of puberty. Many more adipokines are secreted by WAT including omentin, 52,65-67 9,36,62,68 adrenarche in girls with Prader-Willi syndrome. Interestingly, sex puberty. adrenarche; however, both are not required factors. Thus, leptin and adiponectin might be able to influence In gonadarche, leptin can stimulate the secretion of kisspeptin, and subsequently activation of the HPG axis, which eventually increases the expression of estrogen and androstenedione in the ova- 58 2,60 65-67 The expression of these ries (Figure 2). Ob gene in WAT, resulting in the synthesis and secretion of leptin. Thus, high levels of leptin promote onset of puberty in girls via secre- tion of kisspeptin, and estrogen stimulates leptin secretion addition- ally. Moreover, adiponectin can affect the HPG axis due to the expression of adiponectin receptors in the hypothalamus, pituitary In return, estrogen stimulates the expression of the 59 gland, and gonads. onset as it inhibits the secretion of kisspeptin and GnRH in the hypo- thalamus and the release of GH and LH in the pituitary gland, and 2,60-62 52,60 63 girls with central precocious puberty (CPP). Moreover, total adiponectin had negative correlations with progression of puberty in girls (defined by Tanner stages), whereas HMW adiponectin had FIGURE 2 Adipokinesaffectingthe initiation of puberty in girls. Leptin stimulates the release of kisspeptin in KNDy neurons, which activates the hypothalamus to produce gonadotropin releasing hormone (GnRH). In response to the release of GnRH, the pituitary gland secretes follicle stimulating hormone (FSH) and luteinising hormone (LH), which stimulates the ovaries to release estrogen resulting in the formation of secondary sex characteristics in girls. Estrogen stimulates the production of leptin. Adiponectin inhibits GnRH release resulting in reduced levels of GnRH and thereby a delayed onset of puberty. TNF- α and IL-6 inhibit the production of adiponectin and therefore stimulate the onset of puberty In detail, adiponectin is a regulator of puberty thereby inhibiting the onset of puberty (Figure 2). with obesity often have low levels of adiponectin. et al. showed that total adiponectin was significantly lower, whereas high molecular weight (HMW) adiponectin was significantly higher in ment. 55 63 develop a chronic low-grade inflammatory state, which can be indi- cated by a high level of circulating inflammatory cytokines like TNF-α 64 Individuals Sitticharoon positive associations with LH levels and the progression of puberty in 63 visfatin, resistin, and chemerin. and visfatin are expressed in the ovaries. adipokines in the ovaries suggests a role within the reproductive sys- tem; however, the exact biological processes have to be examined. Thus, specifically leptin, adiponectin, and inflammatory cytokines pro- duced by WAT could be permissive key players during an early onset of puberty in girls with obesity. As an exception, HMW adiponectin seems to have a stimulatory effect on peripheral repro- ductive function as HMW is not able to cross the blood brain 63 barrier. 4 | Markers that are used to assess puberty onset in boys are THE ONSET OF PUBERTY IN BOYS spermarche, voice break, testicular volume, and pubic hair develop- 35 spermarche develop in the early stages of puberty onset, voice In women, omentin, chemerin, While pubic hair development, larger testicular volume, and 69 testicular volume increases, which occurs at an average age of break usually appears in later stages of puberty. Generally, first 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 6 of 10 NIEUWENHUIS ET AL. 11.9 years, followed by the development of pubic hair at 12.2 years of average, and lastly, boys experience spermarche around an aver- 55 related with leptin levels. Thereby, leptin plausibly has a minor impact in adrenarche in boys. Since leptin receptors are found in the hypothalamus, pituitary gland, and testes, they might be involved in the onset of puberty by affecting the HPG axis during gonadarche. Leptin stimulates the release of kisspeptin and GnRH, and as a consequence, it accelerates the onset of puberty (Table 1, Figure 3). In contrast, adiponectin inhibits the secretion of GnRH, GH, LH, and FSH therewith delaying the onset of puberty. However, adiponectin levels are generally lower in men compared with women and even lower in men with obe- age age of 13.4 years. 70 4.1 | Fat storage Many aspects of the reproductive physiology are energetically demanding,71 and therefore, an adequate energy level is necessary. In boys, a dynamic change in body composition occurs around the age of 10 to 13 years, in which they gain approximately 40% of sity. culating inflammatory cytokines. levels can stimulate the HPG axis and therewith an early onset of puberty in boys. Nevertheless, leptin can inhibit the production of tes- 72 mostly consisting of lean mass, which causes exhaustion of most of fat. Subsequently, a growth spurt follows in which they gain tissue 72 in boys, an adequate amount of body fat is important in the onset of their body fat. These alterations in amount of body fat indicate that 4.2 | Puberty in boys is initiated by the release of kisspeptin. As mentioned before, this activates the HPG axis, resulting in the release of GnRH from the hypothalamus, and consequently the release of LH and FSH 9,74 puberty. tosterone from the testes, to estrogen (Figure 3). of the development of secondary sex characteristics in boys. Additionally, leptin can affect fertility in men as it can modulate the nutritional support of spermatogenesis, and moreover, dysfunction of spermatogenesis is associated with an increased leptin level and 73 58 2,60-62 HPG axis from the pituitary gland (Figure 1). and LH stimulates the secretion of testosterone from the testes, which inhibits the release of kisspeptin from the KNDy neurons and 9,48 in men, the release of kisspeptin is more consistent, causing a con- 29,48 subsequently GnRH from the hypothalamus. receptors expressed on KNDy neurons. In humans, KNDy neurons Contrarily to women, LH-induced testosterone levels lead to the stant release of LH. development of secondary sex characteristics in boys. differences between sexes in kisspeptin release are related to a sex- specific and sex steroid-dependent kisspeptin system as estrogen and progesterone modulate kisspeptin activity through the sex-steroid 48 in the infundibular nucleus are involved in negative and positive sex- 48 tal exposure to sex steroids and result in sex-specific differences in steroid feedbacks. kisspeptin release. These sexual dimorphisms are induced by perina- 75,76 4.3 | Adipokines The association between obesity and puberty onset in boys is rather controversial compared with findings in girls. Most studies reported an early onset of puberty in boys associated with increased ate adipose tissue from actual breast tissue. stages are more difficult to assess than female stages as boys lack a more determined marker such as menarche. Thirdly, puberty onset can be indicated by the activation of the HPG axis, and the presence of these secondary sex characteristics is the result of hormonal 2 14,17,22,23,50,51,77,78 BMI, 20,49 all while others reported no associations at Current markers used 79 16,80 or a delayed onset of puberty (Table 1). The presence of excessive adipose tissue can be involved in puberty onset in boys as the secretion of adipokines can modulate both adrenarche and gonadarche. Leptin can affect adrenarche by modulating both the HPG and HPA axes,33 and moreover, androgen levels were positively 55 nal androgen secretion in boys with premature adrenarche was not associated with plasma leptin levels. Nevertheless, enhanced adre- 9 In more detail, 61,62 adiponectin, and individuals with obesity often have high levels of cir- Moreover, inflammatory cytokines, TNF-α, and IL-6, inhibit expression of the leptin receptor in the testis. FSH induces spermatogenesis, too. function and role still have to be examined. 64 High leptin and low adiponectin and fat tissue can convert testosterone Both processes might result in the delay 29,61,79 81,82 In men, other adipokines like chemerin are found in the gonads 65 Thus, particularly high leptin and low adiponectin levels stimulate the HPG axis and thereby accelerate the onset of puberty in boys. Additionally, leptin can dysregulate the development of secondary sex characteristics and spermatogenesis by affecting testosterone levels and nutritional sup- port of spermatogenesis. 5 | LIMITATIONS AND FUTURE RESEARCH DIRECTIONS Even though multiple epidemiological studies have shown the link between puberty onset and obesity, there are some important limita- tions. Firstly, determining both the onset and stage of puberty is rather difficult. For instance, assessing the stage of breast develop- ment in girls with obesity is complicated as clinicians should differenti- 2 changes in response to the activated HPG axis. to determine the onset of puberty refer to secondary sex characteris- tics, such as testicular volume in boys and breast development in girls. A more accurate measurement of puberty onset would be to combine secondary sex characteristics with plasma or serum hormone level measurements such as LH, FSH, adipokines, e.g. leptin. Thereby, differences in puberty measurements could explain variations in the age of puberty onset between boys and girls within different Thereby, resistin is expressed in the testes of rats, but its exact 83 Secondly, male pubertal 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License NIEUWENHUIS ET AL. 7 of 10 FIGURE 3 Adipokines affecting the initiation of puberty in boys. Leptin activates kisspeptin secretion in KNDy neurons, this activates the production of gonadotropin releasing hormone (GnRH) from the hypothalamus. GnRH stimulates the pituitary gland to secrete follicle stimulating hormone (FSH) and luteinising hormone (LH), activating the production of testosterone from the testes allowing the development of secondary sex characteristics. Leptin also inhibits the production of testosterone, which may cause a delayed onset of puberty. Adiponectin inhibits GnRH release. Low levels of adiponectin, as a result of TNF-α and IL-6 expression, lead to a reduced inhibition of GnRH. In response to GnRH release, the pituitary gland will secrete FSH and LH, and the testes will produce testosterone resulting in the development of secondary sex characteristics in boys countries, and In addition, the inclusion of a of puberty. ferent time points is complicated, as subjects examined several decades ago presented pronounced differences concerning lifestyle patterns such as nutrition and exercise habits. Lastly, obesity or over- weight is often determined by BMI, a classification based on weight and height measurements. Additionally, it is important that all studies studies or across continents, ethnicities proper age range (8-16 years) is important when assessing the onset (Figure 4). 12-15,17,20-23,49,77-79,84,85 30,47 Furthermore, comparison between studies from dif- 86 Specifically in children, BMI is often dependent on age and growth use the same anthropometric standards and sex-specific cut-offs. 13,14,16-23,49-51,77-80 fat and would represent a more accurate measurement in its regard. Based on this review, several suggestions can be made for further research. Firstly, the roles of adipokines like resistin, chemerin, visfatin, and omentin in puberty onset, fertility, and sexual maturation should be examined in detail. Secondly, future research examining the onset of puberty should combine indicators of puberty onset (e.g. breast development or testicular volume) with plasma or serum hor- mone measurements such as LH, FSH, sex-steroids, adipokines (e.g. spurts. ment in case of growth spurts. distribution of body fat should be taken into account in determining puberty and obesity in children. For instance, the body adiposity index (BAI), which was introduced in 2011 by Bergman et al.,87 uses hip cir- cumference and height in order to estimate the percentage of body 87 Thereby, BMI is a less accurate measure- F I G U R E 4 87,88 Therefore, both percentage and Average age of puberty onset in Europe, China, and the United States according to several studies from Table 1. Age of puberty onset ranges from 8.47 to 13.33 years in girls and from 8.63 leptin), and body fat distribution (e.g. BAI,87 waist-hip ratio's and/or dual-energy X-ray absorptiometry (DXA)2). Additionally, defining con- sistent and general measurements of puberty in both boys and girls, combined with a proper age range (8-16 years), would facilitate the comparisons between different studies and their results. 12-15, 17, 20-23, 25-29, 31 to 13.7 years in boys. included if average age of markers used to assess puberty was not reported. Pink: girls. Blue: boys Studies (Table 1) were not 39, 56 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 8 of 10 NIEUWENHUIS ET AL. 6 | CONCLUSION In conclusion, epidemiological data regarding obesity and puberty onset in girls show similar outcomes as adiposity results in the early onset of puberty in girls. 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BMC Womens Health. 2018;18(1):168-174. thereby an early onset of obesity. leptin can inhibit the production of testosterone in boys and subse- quently inhibit the development of secondary sex characteristics affecting spermatogenesis. for other adipokines, like resistin and omentin, are present in the testes and ovaries suggesting a role in puberty or reproduction; 58, 71 however, their plausible function is still unknown. that adipokines may be key regulators in an early onset of puberty in both girls and boys with obesity, specifically by affecting the HPG axis during gonadarche. Future research should focus on assessing puberty onset by measuring consistent puberty markers and determine the percentage of body fat and its distribution and adipokines and hormone serum levels particularly involved in the HPG axis. CONFLICTS OF INTEREST The authors declare no conflict of interest. FUNDING INFORMATION This research was funded by Europees Fonds voor Regionale Ontwikkeling (EFRO), project BriteN 2016. ORCID Ilse A.C. Arnoldussen Amanda J. Kiliaan https://orcid.org/0000-0002-7395-5284 https://orcid.org/0000-0002-2158-6210 13, 14, 16-26, 29-32 Furthermore, several receptors Nevertheless, We conclude Search strategy We searched PubMed for articles published before Novem- ber 15th, 2019 using relevant keywords, including ‘onset of puberty and adiposity/obesity’, ‘onset of puberty’, ‘children with obesity’, ‘adipose tissue’, ‘childhood obesity’, ‘adiposity’, ‘obesity’, ‘adipokine(s)’, ‘HPG axis’, ‘adipokines ovary/ova- ries’, or ‘adipokines testes’, either alone or in combination. 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Obesity Reviews. 2020;21:e13005. https://doi.org/ 10.1111/obr.13005 1467789x, 2020, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/obr.13005, Wiley Online Library on [10/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are goverUtoevaluación de Práctica Pre-Profesional Nombre del Estudiante: ________ Fecha: ________ ### Parte 1: Reflexiones sobre la experiencia 1. ¿Cómo describirías tu experiencia general en el Hospital Escuela y Clínicas? - [ ] Excelente - [ ] Buena - [ ] Regular - [ ] Mala - [ ] Muy mala (Espacio para comentarios adicionales) _____________________ 2. ¿Qué habilidades o conocimientos consideras que has desarrollado durante tu práctica? (Selecciona todas las que apliquen) - [ ] Trabajo en equipo - [ ] Comunicación efectiva - [ ] Manejo de situaciones clínicas - [ ] Evaluación y diagnóstico - [ ] Otras: _______ (Espacio para comentarios adicionales) _____________________ 3. ¿Cuál fue el aspecto más valioso que te llevas de esta experiencia? (Respuesta abierta) _____________________ ### Parte 2: Sugerencias para el futuro 4. ¿Qué te gustaría que se mejorara o se añadiera en el programa para el próximo año? (Respuesta abierta) _____________________ 5. ¿Qué tipo de actividades adicionales crees que podrían enriquecer la experiencia de los futuros estudiantes? (Respuesta abierta) _____________________ ### Parte 3: Supervisión Institucional 6. ¿Cómo calificarías la supervisión institucional del área social durante tu práctica? - [ ] Excelente - [ ] Buena - [ ] Regular - [ ] Mala - [ ] Muy mala (Espacio para comentarios adicionales) _____________________ 7. ¿Qué aspectos de la supervisión consideras que fueron positivos? (Respuesta abierta) _____________________ 8. ¿Qué sugerencias tienes para mejorar la supervisión en el área social? (Respuesta abierta) _____________________ ### Parte 4: Exposición Final 9. ¿Cómo te sentiste con respecto a tu desempeño en la exposición final? - [ ] Muy satisfecho/a - [ ] Satisfecho/a - [ ] Neutral - [ ] Insatisfecho/a - [ ] Muy insatisfecho/a (Espacio para comentarios adicionales) _____________________ 10. ¿Qué elementos crees que fueron tus puntos fuertes durante la exposición? (Respuesta abierta) _____________________ 11. ¿Qué aspectos te gustaría mejorar en futuras exposiciones? (Respuesta abierta) _____________________ ### Parte 5: Comentarios finales 12. ¿Tienes algún comentario adicional que te gustaría compartir sobre tu experiencia en la práctica pre-profesional? (Respuesta abierta) _____________________Câu 1: Đặc trưng nào sau đây là một trong những yếu tố cốt lõi của trí tuệ nhân tạo? A. Tự động hóa quy trình làm việc B. Khả năng học tập và thích nghi từ dữ liệu C. Khả năng sử dụng năng lượng hiệu quả D. Thực hiện các phép tính toán học nhanh chóng Đáp án: B. Khả năng học tập và thích nghi từ dữ liệu Câu 2: Trí tuệ nhân tạo (AI) chủ yếu được sử dụng để làm gì? A. Phân tích dữ liệu và đưa ra quyết định dựa trên dữ liệu B. Thiết kế hệ thống mạng C. Giảm lượng tiêu thụ điện năng D. Thực hiện các công việc thể chất Đáp án: A. Phân tích dữ liệu và đưa ra quyết định dựa trên dữ liệu Câu 3: Hệ thống AI được gọi là “học máy” (machine learning) khi nó có khả năng: A. Tự động sửa chữa lỗi trong phần mềm B. Tạo ra các hệ thống mạng bảo mật C. Học hỏi và cải thiện hiệu suất mà không cần lập trình rõ ràng D. Tăng tốc độ xử lý của phần cứng Đáp án: C. Học hỏi và cải thiện hiệu suất Câu 4: Khả năng học của AI liên quan đến yếu tố nào sau đây? A. Học từ kinh nghiệm và dữ liệu mới để cải thiện hiệu suất B. Ghi nhớ tất cả các lệnh do con người cung cấp C. Chạy các chương trình mà không cần cập nhật D. Sửa lỗi phần mềm một cách tự động Đáp án: A. Học từ kinh nghiệm và dữ liệu mới để cải thiện hiệu suất Câu 5: Khả năng suy luận trong AI giúp hệ thống thực hiện điều gì? A. Phát triển khả năng thể hiện cảm xúc B. Sử dụng thông tin để đưa ra các quyết định có căn cứ C. Tăng tốc độ xử lý dữ liệu D. Sao chép chính xác các hành vi của con người Đáp án: B. Sử dụng thông tin để đưa ra các quyết định có căn cứ Câu 6: Khả năng nhận thức của AI là gì? A. Khả năng tự nhận biết và điều chỉnh hành vi của nó dựa trên môi trường B. Khả năng xử lý dữ liệu với tốc độ nhanh hơn C. Khả năng làm việc liên tục không cần nghỉ D. Khả năng thu thập dữ liệu từ các cảm biến và hệ thống khác Đáp án: A. Khả năng tự nhận biết và điều chỉnh hành vi của nó dựa trên môi trường Câu 7: Khả năng hiểu ngôn ngữ tự nhiên (NLP) của AI cho phép hệ thống: A. Xử lý văn bản và ngôn ngữ giống như con người B. Dịch thuật chính xác từ ngôn ngữ này sang ngôn ngữ khác C. Thay thế hoàn toàn con người trong việc viết và giao tiếp D. Tăng cường khả năng suy nghĩ trừu tượng Đáp án: A. Xử lý văn bản và ngôn ngữ giống như con người Câu 8: AI có khả năng giải quyết vấn đề khi nào? A. Khi nó sử dụng các thuật toán để tìm ra giải pháp tối ưu cho các vấn đề phức tạp B. Khi nó thay thế toàn bộ con người trong mọi công việc C. Khi nó tự động sửa chữa các lỗi phần mềm D. Khi nó cung cấp thông tin chi tiết về dữ liệu mà không cần bất kỳ sự can thiệp nào Đáp án: A. Khi nó sử dụng các thuật toán để tìm ra giải pháp tối ưu cho các vấn đề phức tạp Câu 9: Khả năng học của AI là gì? A. AI có thể học từ dữ liệu và kinh nghiệm mới. B. AI có thể tự sửa lỗi mà không cần dữ liệu đầu vào. C. AI có thể cải thiện hiệu suất thông qua học tập. D. AI không cần cập nhật khi học tập từ dữ liệu. Đáp án: • Đúng: A, C • Sai: B, D Câu 10: Khả năng suy luận của AI giúp hệ thống thực hiện điều gì? A. AI có thể đưa ra quyết định dựa trên dữ liệu. B. AI có thể suy nghĩ giống con người mà không cần dữ liệu. C. AI sử dụng thông tin để phân tích và đưa ra lựa chọn hợp lý. D. AI tự động đưa ra quyết định mà không cần học tập trước đó. Đáp án: • Đúng: A, C • Sai: B, D Câu 11: AI có khả năng nhận thức và điều chỉnh hành vi dựa trên môi trường xung quanh không? A. AI có thể nhận biết thay đổi trong môi trường và điều chỉnh hành vi. B. AI luôn cần con người giám sát để đưa ra quyết định. C. AI tự động thay đổi mà không cần lập trình lại khi môi trường thay đổi. D. AI không có khả năng điều chỉnh theo môi trường. Đáp án: • Đúng: A, C • Sai: B, D Câu 12: Khả năng giải quyết vấn đề của AI được biểu hiện như thế nào? A. AI có thể áp dụng các thuật toán để tìm ra giải pháp tối ưu. B. AI giải quyết vấn đề mà không cần dữ liệu đầu vào. C. AI tự động phân tích và đưa ra các phương án giải quyết dựa trên dữ liệu. D. AI chỉ có thể giải quyết vấn đề khi được lập trình trước. Đáp án: • Đúng: A, C • Sai: B, DCâu 1: Chất khử là A. chất nhường electron. B. chất nhận electron. C. chất nhường proton. D. chất nhận proton. Câu 2: Phản ứng oxi hóa - khử là A. phản ứng hóa học trong đó có sự chuyển proton. B. phản ứng hóa học trong đó có sự thay đổi số oxi hóa. C. phản ứng hóa học trong đó phải có sự biến đổi hợp chất thành đơn chất. D. phản ứng hóa học trong đó sự chuyển electron từ đơn chất sang hợp chất. Câu 3: Sự oxi hóa một chất là quá trình A. nhận electron của chất đó. B. làm giảm số oxi hóa của chất đó. C. nhường electron của chất đó. D. làm thay đổi số oxi hóa của chất đó. Câu 4: Phát biểu nào dưới đây không đúng? A. Sự khử là sự mất hay cho electron. B. Sự oxi hoá là sự mất electron. C. Chất khử là chất nhường electron. D. Chất oxi hoá là chất nhận electron. Câu 5: Trong các phản ứng sau, phản ứng nào là phản ứng oxi hóa - khử? A. CaCO3 CaO + CO2. B. 2KClO3 2KCl + 3O2. C. 2NaHCO3 Na2CO3 + H2O + SO2. D. 2Fe(OH)3 Fe2O3 + 3H2O. Câu 6: Cho phương trình phản ứng: Fe + CuSO4 Cu + FeSO4. Vai trò của Fe trong phản ứng là A. chất oxi hóa. B. chất bị khử. C. chất khử. D. vừa là chất khử, là chất oxi hóa. Câu 7: Cho phương trình phản ứng: Cl2 + 2H2O 2HCl + 2HClO. Vai trò của Cl2 trong phản ứng là A. chất oxi hóa. B. chất bị khử. C. chất khử. D. vừa là chất khử, là chất oxi hóa. Câu 8: Cho phương trình phản ứng: AgNO3 + HCl AgCl + HNO3. Vai trò của AgNO3 trong phản ứng là A. chất oxi hóa. B. chất bị khử. C. không là chất khử, không là chất oxi hóa. D. vừa là chất khử, là chất oxi hóa. Câu 9: Trong các phản ứng sau, phản ứng nào không phải là phản ứng oxi hóa khử? A. Fe + 2HCl FeCl2 + H2. B. Zn + CuSO4 ZnSO4 + Cu. C. CH4 + Cl2 CH3Cl + HCl. D. BaCl2 + H2SO4 BaSO4 + 2HCl. Câu 10: Trong các phản ứng sau phản ứng nào là phản ứng oxi hóa - khử? A. NaOH + HCl NaCl + H2O. B. 2Fe(OH)3 + 3H2SO4 Fe2(SO4)3 + 6H2O. C. CaCO3 + 2HCl CaCl2 + H2O + CO2. D. 2CH3COOH + Mg (CH3COO)2Mg + H2. Câu 11: Số oxi hóa của S trong SO2 bằng A. +4 B. -4 C. +2 D. -2 Câu 12: Số oxi hóa của C trong CH4 bằng A. +4 B. -4 C. +1 D. -1 Câu 13: Sơ đồ: Cu → Cu+2 + 2e biểu thị quá trình A. oxi hóa. B. nhận electron. C. phân hủy. D. khử Câu 14: Sơ đồ: N+5 + 3e → N+2 biểu thị quá trình A. oxi hóa B. khử C. nhận proton D. hóa hợp Câu 15: Sục khí SO2 vào dung dịch KMnO4 (thuốc tím), màu tím nhạt dần rồi mất màu (biết sản phẩm tạo thành là K2SO4, MnSO4, H2SO4 và H2O). Nguyên nhân là do A. SO2 đã oxi hóa KMnO4 thành MnO2. B. SO2 đã khử KMnO4 thành Mn+2. C. KMnO4 đã khử SO2 thành S+6. D. H2O đã oxi hóa KMnO4 thành Mn+2. Câu 17: Hỗn hợp tecmit dùng hàn gắn đường ray có thành phần chính là aluminium (Al) và iron (III) oxide (Fe2O3). Phản ứng xảy ra khi đung nóng hỗn hợp tecmit như sau: Fe2O3 + 2Al 2Fe + Al2O3. Phát biểu nào dưới đây là đúng? A. Al là chất bị oxi hoá. B. Fe2O3 là chất nhường electron. C. Fe2O3 là chất bị oxi hóa. D. Al2O3 là chất nhận electron. Câu 18: Phản ứng thu nhiệt là phản ứng A. giải phóng năng lượng dưới dạng nhiệt. B. hấp thu năng lượng dưới dạng nhiệt. C. cung cấp năng lượng dưới dạng nhiệt. D. hấp thu năng lượng dưới dạng hóa năng. Câu 19: Phản ứng nhiệt nhôm là phản ứng giữa bột nhôm và iron (III) oxide sinh ra một lượng nhiệt rất lớn và được ứng dụng dùng để hàn đường ray. Phản ứng nhiệt nhôm là phản ứng A. thu nhiệt. B. chưa xác định được. C. tỏa nhiệt. D. vừa thu nhiệt, vừa tỏa nhiệt. Câu 20: Phản ứng nào trong các phản ứng dưới đây là phản ứng thu nhiệt? A. Vôi sống tác dụng với nước: CaO + H2O → Ca(OH)2. B. Đốt cháy than: C + O2 CO2. C. Đốt cháy cồn: C2H5OH + 3O2 2CO2 + 3H2O. D. Nung đá vôi: CaCO3 CO2 + CaO. Câu 21: Điều kiện nào sau đây không phải là điều kiện chuẩn? A. Áp suất 1 bar và nhiệt độ 25 0C. B. Áp suất 1 bar và nhiệt độ 298 K. C. Áp suất 1 bar và nhiệt độ 25 0C hay 298 K. D. Áp suất 1 bar và nhiệt độ 25K. Câu 22: Điều kiện nào sau đây là điều kiện chuẩn? A. Áp suất 1 bar và nhiệt độ 25 K. B. Áp suất 1 bar và nhiệt độ 298 0C. C. Áp suất 1 bar và nhiệt độ 298 K. D. Áp suất 1 bar và nhiệt độ 25K. Câu 23: Nồng độ đối với chất tan trong dung dịch ở điều kiện chuẩn là? A. 0,01 mol/L. B. 0,1 mol/L. C. 1 mol/L. D. 0,5 mol/L. Câu 24: 1 mol chất khí ở điều kiện chuẩn chiếm thể tích bằng bao nhiêu? A. 24,79 lít. B. 2,479 lít. C. 22,4 lít. D. 2,24 lít. Câu 25: Kí hiệu nhiệt tạo thành chuẩn của một chất là A. . B. . C. H298.. D. . Câu 26: Số oxi hóa của một nguyên tử trong phân tử là A. điện tích quy ước của nguyên tử trong phân tử khi coi tất cả các electron liên kết đều chuyển hoàn toàn về nguyên tử của nguyên tố có độ âm điện lớn hơn. B. hóa trị của nguyên tử nguyên tố đó. C. điện tích thực của nguyên tử nguyên tố đó. D. độ âm điện của nguyên tử nguyên tố đó. Câu 27: Fe2O3 là thành phần chính của quặng hematite đỏ, dùng để luyện gang. Số oxi hoá của iron (Fe) trong Fe2O3 là A. +3. B. 3+. C. 3-. D. -3. Câu 28: Trong phản ứng oxi hóa – khử, chất nhận electron được gọi là A. chất khử. B. chất oxi hoá. C. acid. D. base. Câu 29: Các phản ứng quan trọng gắn liền với cuộc sống như sự cháy của than, củi; sự cháy của xăng, dầu trong các động cơ đốt trong,…thường thuộc loại phản ứng nào? A. Phản ứng thế. B. Phản ứng cộng. C. Phản ứng phân hủy. D. Phản ứng oxi hóa - khử. Câu 30: Enthalpy phản ứng chuẩn có kí hiệu là A. . B. . C. . D. .1. Da cosa si ricavano le materie plastiche? a) Sabbia, calce e argilla b) Argilla e acqua c) Petrolio e derivati d) Gesso e ferro 2. Qual è uno svantaggio delle plastiche tradizionali? a) Costano troppo b) Si degradano molto lentamente c) Sono conduttrici di elettricità d) Contengono ossigeno e idrogeno 3. Le materie plastiche sono utili perché: a) Sono sempre biodegradabili b) Assorbono acqua e luce c) Resistono bene solo alle alte temperature d) Sono leggere, modellabili e resistenti 4. Quali sono i principali materiali artificiali da costruzione? a) Rame, ferro, zinco e piombo b) Laterizi, ceramica e vetro c) Sabbia, ghiaia e marmo d) Legno, carbone e calcare 5. Come si classificano i laterizi in base all’uso? a) Opachi e trasparenti b) Per strutture, coperture, pavimenti e decorazioni c) Solidi e liquidi d) Per interni ed esterni 6. I laterizi sono ottenuti da: a) Argilla cotta b) Marmo frantumato c) Vetro fuso d) Plastica riciclata 7. I materiali leganti vengono usati per: a) Rivestire pareti b) Unire materiali da costruzione c) Colorare la ceramica d) Lucidare superfici 8. Il cemento si ottiene da: a) Cottura di Sabbia e acqua b) Cottura di Calce viva e acqua c) Cottura di calcare e argilla d) Fusione del ferro 9. Quale materiale è usato per il cemento armato? a) Acciaio b) Mattoni pieni c) Fibra di vetro d) Rame lucido 10. Il vetro si produce principalmente dalla: a) Calce e argilla b) Silice e ossidi c) Resina e olio d) Gesso e caolino 11. Il vetro pyrex è utilizzato per: a) Tetti e coperture b) Contenitori resistenti al calore c) Oggetti decorativi in legno d) Pavimentazioni industriali 12. Il metodo "float glass" serve per produrre: a) Tubi in PVC b) Lastre di vetro c) Mattoni refrattari d) Bottiglie in plastica 13. Qual è una proprietà del vetro? a) È biodegradabile b) È un isolante elettrico c) Assorbe umidità d) Conduce il calore facilmente 14. Un vantaggio dell’uso delle plastiche è che: a) Sono facilmente modellabili b) Si sciolgono con l’acqua c) Sono trasparenti come il vetro d) Durano poco 15. Le rocce metamorfiche sono: a) Rocce trasformate da calore e pressione b) Completamente artificiali c) Usate solo per decorare d) Composte da sabbia e gesso 16. Il calcestruzzo è formato da: a) Solo sabbia e cemento b) Cemento, sabbia, acqua e ghiaia c) Argilla e vetro d) Cemento e legnoQuale dei seguenti numeri è un numero intero relativo? a) -3/4 b) 5.25 c) -8 d) √9 Risolvi: -6 + (-3). a) 9 b) -9 c) 3 d) -3 Calcola: -2 * 7. a) -14 b) 14 c) -5 d) 5 Quale di queste espressioni è equivalente a -(-5)? a) 5 b) -5 c) 10 d) -10 Quanto vale 3^(-2)? a) 1/9 b) 9 c) -9 d) 1/3 Qual è il risultato di (-4)^3? a) -64 b) 64 c) -12 d) 12 Sottrai -8 da -3. a) 5 b) -5 c) -11 d) 11 Calcola: 2^(-3). a) 1/8 b) 8 c) -8 d) -1/8 Quale dei seguenti numeri è un intero relativo maggiore di -5? a) -6 b) -4 c) 0 d) -1 Quale delle seguenti affermazioni è falsa? a) Ogni numero naturale è anche un numero intero relativo. b) Un numero negativo è sempre minore di zero. c) L'opposto di un numero positivo è negativo. d) La somma di due numeri negativi è sempre negativa.Elabora un cuestionario con 3 opciones múltiples, los siguientes conceptos : Concepto 1: Aduana Definición: Lugar habilitado por la autoridad aduanera para el despacho de mercancías y la prestación de servicios relacionados con el comercio exterior. Concepto 2: Autoridad Aduanera Definición: Entidad encargada de aplicar y supervisar el cumplimiento de la Ley Aduanera y las disposiciones relacionadas con el comercio exterior. Concepto 3: Mercancías Definición: Todos los objetos, productos y cosas susceptibles de ser comercializados y sujetos a importación o exportación. Concepto 4: Valor en Aduana Definición: El valor determinado de acuerdo con las normas y métodos establecidos en la Ley Aduanera y su Reglamento. Concepto 5: Declarante Definición: Persona que realiza la declaración de las mercancías ante la autoridad aduanera. Concepto 6: Importación Definición: Introducción de mercancías extranjeras al territorio aduanero. Concepto 7: Exportación Definición: Envío de mercancías nacionales o nacionalizadas fuera del territorio aduanero. Concepto 8: Despacho Aduanero Definición: Conjunto de trámites y actividades necesarios para la importación o exportación de mercancías. Concepto 9: Agente Aduanal Definición: Persona autorizada para representar a terceros en trámites aduaneros y realizar el despacho de mercancías. Concepto 10: Pedimento Definición: Documento que contiene la declaración de las mercancías y los datos necesarios para su despacho. Concepto 11: Reconocimiento Aduanero Definición: Inspección física o documental de las mercancías realizada por la autoridad aduanera. Concepto 12: Destinatario Definición: Persona a quien se envían las mercancías importadas o exportadas. Concepto 13: Pasajero Definición: Persona que cruza la frontera y lleva consigo mercancías no destinadas a la venta. Concepto 14: Régimen Aduanero Definición: Situación jurídica en la que se encuentran las mercancías en el territorio aduanero. Concepto 15: Deposito Fiscal Definición: Lugar autorizado para el resguardo de mercancías bajo control aduanero. Concepto 16: Mercancías Restringidas Definición: Mercancías cuya importación o exportación está sujeta a restricciones o regulaciones. Concepto 17: Mercancías Prohibidas Definición: Mercancías cuya importación o exportación está prohibida por ley. Concepto 18: Valor Comercial Definición: Precio al que se venden mercancías entre partes independientes en una transacción de compraventa. Concepto 19: Valor en Transacción de Mercancías Similares Definición: Valor de las mercancías importadas de características similares a las declaradas. Concepto 20: Valor en Transacción de Mercancías Idénticas Definición: Valor de las mercancías importadas que son idénticas a las declaradas. Concepto 21: Valor en Transacción de Mercancías Valoradas Definición: Valor de las mercancías importadas que no pueden ser valoradas de acuerdo con otros métodos.Crea un quiz con le seguenti domande. Inserisci anche la spiegazione. Domande Vero/Falso: 1. Vero o Falso: Se moltiplichiamo entrambi i membri di una disequazione per un numero negativo, il segno dell'ineguaglianza cambia. o Risposta: Vero o Spiegazione: Quando moltiplichiamo o dividiamo entrambi i membri di una disequazione per un numero negativo, il segno dell'ineguaglianza si inverte. 2. Vero o Falso: Una disequazione può avere solo una soluzione. o Risposta: Falso o Spiegazione: Una disequazione può avere zero, una o infinite soluzioni, a seconda dei valori coinvolti. 3. Vero o Falso: Se sommiamo o sottraiamo la stessa quantità da entrambi i membri di una disequazione, la soluzione rimane invariata. o Risposta: Vero o Spiegazione: Aggiungere o sottrarre la stessa quantità da entrambi i membri di una disequazione non cambia la relazione tra le soluzioni. 4. Vero o Falso: Se abbiamo una disequazione del tipo 2x>102x>10, la soluzione è x<5x<5. o Risposta: Vero o Spiegazione: Dividendo entrambi i membri per 22, otteniamo x>5/2x>5/2, che può essere semplificato a x>2.5x>2.5 o x>5/2x>5/2. 5. Vero o Falso: Una disequazione può avere solo numeri interi come soluzioni. o Risposta: Falso o Spiegazione: Le soluzioni di una disequazione possono essere numeri razionali o reali, non solo numeri interi. 6. Vero o Falso: Una disequazione del tipo 3x−2<53x−2<5 ha x>7/3x>7/3 come soluzione. o Risposta: Falso o Spiegazione: La soluzione corretta è x<7/3x<7/3 poiché 3x−23x−2 deve essere minore di 55, non maggiore. 7. Vero o Falso: Una disequazione del tipo 4x+7≥3x+54x+7≥3x+5 ha una soluzione unica. o Risposta: Vero o Spiegazione: Sottraendo 3x3x da entrambi i lati otteniamo x+7≥5x+7≥5, che semplificato diventa x≥−2x≥−2, quindi ha una soluzione unica. 8. Vero o Falso: Una disequazione quadratica è un tipo di disequazione di primo grado. o Risposta: Falso o Spiegazione: Una disequazione quadratica coinvolge il quadrato di una variabile e può essere di secondo grado o superiore, mentre una disequazione di primo grado coinvolge solo variabili elevate alla prima potenza. 9. Vero o Falso: Una disequazione del tipo 2(x−3)<82(x−3)<8 può essere risolta dividendo entrambi i membri per 22. o Risposta: Vero o Spiegazione: Dividendo entrambi i membri otteniamo x−3<4x−3<4, che può essere semplificato a x<7x<7 dopo l'aggiunta di 33 ad entrambi i membri. 10. Vero o Falso: Se abbiamo una disequazione del tipo x≤4x≤4 e x≥3x≥3, allora la soluzione è x=4x=4. o Risposta: Falso o Spiegazione: La soluzione è 3≤x≤43≤x≤4, il che significa che xx può essere qualsiasi numero tra 33 e 44, inclusi tutti i valori decimali in questo intervallo. Domande a Risposta Multipla: 11. Qual è la soluzione della disequazione 2x+5>112x+5>11? a) x<3x<3 b) x>3x>3 c) x<8x<8 d) x>8x>8 o Risposta: b) x>3x>3 o Spiegazione: Sottraendo 55 da entrambi i lati otteniamo 2x>62x>6, quindi x>3x>3. 12. Quale delle seguenti è una soluzione della disequazione 3x−1≤83x−1≤8? a) x=3x=3 b) x=1x=1 c) x=0x=0 d) x=4x=4 o Risposta: d) x=4x=4 o Spiegazione: Aggiungendo 11 ad entrambi i lati otteniamo 3x≤93x≤9, quindi x≤3x≤3. 13. Quale delle seguenti disequazioni è equivalente a 2(x+1)>62(x+1)>6? a) 2x>62x>6 b) 2x+2>62x+2>6 c) x+1>3x+1>3 d) x>2x>2 o Risposta: c) x+1>3x+1>3 o Spiegazione: Distribuendo 22 otteniamo 2x+2>62x+2>6, quindi x+1>3x+1>3. 14. Qual è la soluzione della disequazione 5x−4<3x+75x−4<3x+7? a) x<11x<11 b) x>11x>11 c) x<−11x<−11 d) x>−11x>−11 o Risposta: d) x>−11x>−11 o Spiegazione: Sottraendo 3x3x da entrambi i lati otteniamo 2x−4<72x−4<7, quindi 2x<112x<11 e infine x>−11x>−11. ……. 15 Qual è la soluzione della disequazione 2x+3≥5x−12x+3≥5x−1? a) x≤−1x≤−1 b) x≥−1x≥−1 c) x<2x<2 d) x>2x>2 o Risposta: c) x<2x<2 o Spiegazione: Sottraendo 5x5x da entrambi i lati otteniamo −3x+3≥−1−3x+3≥−1, quindi −3x≥−4−3x≥−4. Dividendo entrambi i lati per −3−3, ricordando di invertire il segno, otteniamo x<2x<2. 16 Quale delle seguenti è una soluzione della disequazione 4x−2≤2x+64x−2≤2x+6? a) x≤−2x≤−2 b) x≥−2x≥−2 c) x<2x<2 d) x>2x>2 o Risposta: b) x≥−2x≥−2 o Spiegazione: Sottraendo 2x2x da entrambi i lati otteniamo 2x−2≤62x−2≤6, quindi 2x≤82x≤8 e infine x≥−2x≥−2. 17 Quale delle seguenti è la soluzione della disequazione 3(x−2)>93(x−2)>9? a) x>3x>3 b) x>5x>5 c) x<3x<3 d) x<5x<5 o Risposta: b) x>5x>5 o Spiegazione: Dividendo entrambi i lati per 33, otteniamo x−2>3x−2>3, quindi x>5x>5. 18 Qual è la soluzione della disequazione 2x+4≤102x+4≤10? a) x≤2x≤2 b) x≥2x≥2 c) x<2x<2 d) x>2x>2 o Risposta: a) x≤2x≤2 o Spiegazione: Sottraendo 44 da entrambi i lati otteniamo 2x≤62x≤6, quindi x≤3x≤3. Tuttavia, dovremmo tenere conto che 22 è positivo, quindi la soluzione è x≤2x≤2. 19 Quale delle seguenti disequazioni è equivalente a 2x≤82x≤8? a) x≥4x≥4 b) x≤4x≤4 c) x>4x>4 d) x<4x<4 a. Risposta: b) x≤4x≤4 b. Spiegazione: Dividendo entrambi i lati per 22, otteniamo x≤4x≤4. 20 Quale delle seguenti è una soluzione della disequazione 5(x−3)>105(x−3)>10? a) x<−1x<−1 b) x>−1x>−1 c) x>5x>5 d) x<5x<5 a. Risposta: c) x>5x>5 b. Spiegazione: Dividendo entrambi i lati per 55, otteniamo x−3>2x−3>2, quindi x>5x>5.