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40-451: (Redirected from Human Development ) Human development may refer to: Development of the human body Developmental psychology Development theory Human development (economics) Human Development Index , an index used to rank countries by level of human development Human evolution , the prehistoric process leading to the modern human species Human Development (journal) ,

80-444: A child if they are under the legal age of majority. Conversely, a legal adult may possess none of the maturity and responsibility that is supposed to define them; the mental and physical development and maturity of an individual has been proven to be greatly influenced by their life circumstances. Human organs and organ systems develop in a process known as organogenesis . This begins in the third week of embryonic development, when

120-547: A journal published by Karger See also [ edit ] Human population growth Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Human development . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Human_development&oldid=1238725583 " Category : Disambiguation pages Hidden categories: Short description

160-460: A key role in the formation of new bone cells. Adequate nutrient intake is essential for the production of these hormones, which are critical for proper bone growth. However, a lack of proper nutrition can hinder this process and result in stunted growth . Linear growth takes place in the epiphyseal growth plates (EGP) of long bones. In the growth plate, chondrocytes proliferate, hypertrophy and secrete cartilage extracellular matrix. New cartilage

200-567: A large study based on 5 birth cohorts in Brazil, Guatemala, India, the Philippines and South Africa, faster linear growth at 0–2 years was associated with improvements in adult stature and school performance, but also an increased likelihood of overweight (mainly related to lean mass) and a slightly elevated blood pressure in young adulthood. [REDACTED]  This article incorporates text by Marianne Sandsmark Morseth available under

240-404: A one-celled zygote to an adult human being . Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell ( ovum ). The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences. The embryonic stage covers the first eight weeks of development; at the beginning of the ninth week

280-414: A person's attitude formation. The Tanner stages can be used to approximately judge a child's age based on physical development. Puberty is the process of physical changes through which a child 's body matures into an adult body capable of sexual reproduction . It is initiated by hormonal signals from the brain to the gonads : the ovaries in a girl, the testicles in a boy. In response to

320-423: A variety of proteins, cytokines , and growth factors . These secreted factors will regulate the invasiveness of trophoblast cells that eventually form the placental connection if an embryo implants into the decidua. One of the identifying features of the decidua is the presence of large numbers of leukocytes that are mostly made up of specialized uterine natural killer (uNK) cells and some dendritic cells . As

360-447: Is a stage in the human development considered to begin nine weeks after fertilization. In biological terms, however, prenatal development is a continuum, with many defining features distinguishing an embryo from a fetus. A fetus is also characterized by the presence of all the major body organs, though they will not yet be fully developed and functional and some not yet situated in their final location. The fetus and embryo develop within

400-418: Is debatable, and in invertebrates such as Arthropoda , is analogous at best. Childhood is the age span ranging from birth to adolescence . In developmental psychology , childhood is divided up into the developmental stages of toddlerhood (learning to walk), early childhood (play age), middle childhood (school age), and adolescence (puberty through post-puberty). Various childhood factors could affect

440-413: Is different from Wikidata All article disambiguation pages All disambiguation pages Development of the human body Development before birth, or prenatal development (from Latin natalis  'relating to birth') is the process in which a zygote , and later an embryo , and then a fetus develops during gestation . Prenatal development starts with fertilization and

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480-452: Is known as precocious puberty , and puberty which starts later than usual is known as delayed puberty . Notable among the morphologic changes in size, shape, composition, and functioning of the pubertal body, is the development of secondary sex characteristics , the "filling in" of the child's body; from girl to woman, from boy to man. Biologically, an adult is a human or other organism that has reached sexual maturity. In human context,

520-405: Is lower compared to the 19th century, when it was 15 for girls and 16 for boys. This can be due to any number of factors, including improved nutrition resulting in rapid body growth, increased weight and fat deposition, or exposure to endocrine disruptors such as xenoestrogens , which can at times be due to food consumption or other environmental factors. Puberty which starts earlier than usual

560-471: Is non-spontaneous, meaning it only happens after there are external signals from an implanted embryo. After ovulation, the high levels of progesterone initiate the molecular changes leading to decidualization. The process triggers an influx of decidual leukocytes along with morphological and functional changes of ESCs. The changes in the ESCs result in the endometrium developing a secretory lining that produces

600-527: Is required in some mammalian species where embryo implantation and trophoblast cell invasion of the endometrium occurs, also known as hemochorial placentation . This allows maternal blood to come into direct contact with the fetal chorion , a membrane between the fetal and maternal tissues, and allows for nutrient and gas exchange. However, decidualization-like reactions have also been observed in some species that don't display hemochorial placentation. In humans, decidualization occurs after ovulation during

640-438: Is seen in very early pregnancy in the generalized area where the blastocyst contacts the endometrial decidua . It consists of an increase in secretory functions of the endometrium at the area of implantation, as well as a surrounding stroma that becomes edematous . The decidual reaction occurs only in humans and a few other species. The decidual reaction and decidua are not required for implantation. Evidence can be taken from

680-457: Is subsequently remodeled into bone tissue, causing bones to grow longer. Linear growth is a complex process regulated by the growth hormone (GH) – insulin-like growth factor-1 ( IGF-1 ) axis, the thyroxine/triiodothyronine axis, androgens, estrogens, vitamin D, glucocorticoids and possibly leptin. GH is secreted by the anterior pituitary gland in response to hypothalamic, pituitary and circulating factors. It affects growth by binding to receptors in

720-506: The CC BY-SA 3.0 license. Decidual reaction Decidualization is a process that results in significant changes to cells of the endometrium in preparation for, and during, pregnancy . This includes morphological and functional changes (the decidual reaction ) to endometrial stromal cells (ESCs), the presence of decidual white blood cells (leukocytes), and vascular changes to maternal arteries. The sum of these changes results in

760-432: The embryo remains in a protein shell, the zona pellucida , and undergoes a series of rapid mitotic cell divisions called cleavage . A week after fertilization the embryo still has not grown in size, but hatches from the zona pellucida and adheres to the lining of the mother's uterus . This induces a decidual reaction , wherein the uterine cells proliferate and surround the embryo thus causing it to become embedded within

800-430: The menstrual cycle . After implantation of the embryo, the decidua further develops to mediate the process of placentation. In the event no embryo is implanted, the decidualized endometrial lining is shed or, as is the case with species that follow the estrous cycle , absorbed. In menstruating species , decidualization is spontaneous and occurs as a result of maternal hormones. In non-menstruating species, decidualization

840-421: The respiratory and gastrointestinal tracts and several glands . During childhood, the bones undergo a complex process of elongation that occurs in a specific area called the epiphyseal growth plates (EGP). This process is regulated by various hormones and factors, including the growth hormone, vitamin D, and others. These hormones promote the production of insulin-like growth factor-1 (IGF-1), which plays

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880-530: The uterus , an organ that sits within the pelvis of the mother . The process the mother experiences whilst carrying the fetus or embryo is referred to as pregnancy . The placenta connects the developing fetus to the uterine wall to allow nutrient uptake, thermo-regulation, waste elimination, and gas exchange via the mother's blood supply; to fight against internal infection; and to produce hormones which support pregnancy. The placenta provides oxygen and nutrients to growing fetuses and removes waste products from

920-545: The EGP, and inducing production and release of IGF-1 by the liver. IGF-1 has six binding proteins (IGFBPs), exhibiting different effects on body tissues, where IGFBP-3 is most abundant in human circulation. IGF-1 initiates growth through differentiation and maturation of osteoblasts, and regulates release of GH from the pituitary through feedback mechanisms. The GH/IGF-1 axis is responsive to dietary intake and infections. The endocrine system seems to allow for rapid growth only when

960-483: The accumulation of glycogen and lipid droplets. Furthermore, they begin secreting cytokines, growth factors, and proteins like IGFBP1 and prolactin , along with extracellular matrix (ECM) proteins such as fibronectin and laminin . The increased production of these ECM proteins turns the endometrium into the dense structure known as the decidua, which produces factors that promote trophoblast attachment and inhibit overly aggressive invasion. The decidual reaction

1000-452: The decidua, has been linked with premature birth . The decidualization process is initiated by progesterone, but this requires cyclic adenosine monophosphate (cAMP) to act as the initial signalling molecule to sensitize endometrial cells to progesterone. Consequently, human ESCs have been decidualized in culture with chemical analogs of cAMP and progesterone together. In vitro decidualization results in similar morphological changes to

1040-428: The development of the early embryo, up until implantation. The germinal stage is over at about 10 days of gestation. The zygote contains a full complement of genetic material with all the biological characteristics of a single human being, and develops into the embryo. Embryonic development has four stages: the morula stage, the blastula stage, the gastrula stage, and the neurula stage. Prior to implantation,

1080-405: The embryo is termed a fetus . The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus . The germinal stage takes around 10 days. During this stage, the zygote begins to divide, in a process called cleavage . A blastocyst is then formed and implanted in the uterus . Embryonic development continues with

1120-440: The endometrium changing into a structure called the decidua . In humans, the decidua is shed during childbirth . Decidualization plays an important role in promoting placenta formation between a mother and her fetus by mediating the invasiveness of trophoblast cells. It also triggers the production of cellular and molecular factors that result in structural changes, or remodeling, of maternal spiral arteries . Decidualization

1160-465: The external sex organs. On average, girls begin puberty around ages 10–11 and end puberty around 15–17; boys begin around ages 11–12 and end around 16–17. The major landmark of puberty for females is menarche , the onset of menstruation, which occurs on average between ages 12 and 13; for males, it is the first ejaculation , which occurs on average at age 13. In the 21st century, the average age at which children, especially girls, reach puberty

1200-425: The fact that in ectopic pregnancies and hysterectomies , implantation can occur anywhere in the abdomino-pelvic cavity. Abnormalities in decidualization have been implicated in diseases such as endometriosis , in which impaired decidualization leads to ectopic uterine tissue growth. Lack of decidualization has also been linked to higher rates of miscarriage . Chronic deciduitis , a chronic inflammation of

1240-549: The fetus consists of both maternal and paternal DNA , the decidual leukocytes play a role in suppressing the immune response of the mother to prevent treating the fetus as genetically foreign. Outside of their immune functions, the uNK cells and dendritic cells also act as regulators of maternal spiral artery remodeling and ESC differentiation. ESCs are the connective tissue cells of the endometrium that are fibroblastic in appearance. However, decidualization causes them to swell up and adopt an epithelial cell-like appearance due to

Human development - Misplaced Pages Continue

1280-465: The fetus has more recognizable external features and a set of progressively developing internal organs. A nearly identical process occurs in other species. Human embryonic development refers to the development and formation of the human embryo . It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development . In biological terms, human development entails growth from

1320-398: The fetus' blood. The placenta attaches to the wall of the uterus, and the fetus' umbilical cord develops from the placenta. These organs connect the mother and the fetus. Placentas are a defining characteristic of placental mammals , but are also found in marsupials and some non-mammals with varying levels of development. The homology of such structures in various viviparous organisms

1360-433: The formation of the zygote , the first stage in embryonic development which continues in fetal development until birth . Fertilization occurs when the sperm successfully enters the ovum's membrane. The chromosomes of the sperm are passed into the egg to form a unique genome. The egg becomes a zygote and the germinal stage of embryonic development begins. The germinal stage refers to the time from fertilization, through

1400-415: The gastrula forms three distinct germ layers , the ectoderm , mesoderm and endoderm . The ectoderm will eventually develop into the outer layer of skin and nervous system . The mesoderm will form skeletal muscles , blood cells , the reproductive system , the urinary system , most of the circulatory system , and the connective tissue of the torso. The endoderm will develop into the epithelium of

1440-562: The next stage of gastrulation , when the three germ layers of the embryo form in a process called histogenesis , and the processes of neurulation and organogenesis follow. In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs. The entire process of embryonic development involves coordinated spatial and temporal changes in gene expression , cell growth and cellular differentiation . A nearly identical process occurs in other species, especially among chordates . A fetus

1480-612: The organism is able to consume sufficient amounts of nutrients and signaling from key nutrients such as amino acids and zinc to induce production of IGF-1 is present. At the same time inflammation and increased production of pro-inflammatory cytokines may cause GH resistance and a decrease in circulating IGF-1 and IGFBP-3 which in turn reduces endochondrial ossification and growth. However, the EGP appears to conserve much growth capacity to allow for catch-up growth. Concerns have been raised about associations between catch-up growth and increased risk of non-communicable diseases in adulthood. In

1520-451: The signals, the gonads produce hormones that stimulate libido and the growth, function, and transformation of the brain, bones , muscle , blood , skin , hair , breasts , and sex organs . Physical growth —height and weight—accelerates in the first half of puberty and is completed when an adult body has been developed. Until the maturation of their reproductive capabilities, the pre-pubertal physical differences between boys and girls are

1560-614: The term adult has additional meanings associated with social and legal concepts. In contrast to a legal minor , a legal adult is a person who has attained the age of majority and is therefore regarded as independent, self-sufficient, and responsible. The typical age of legal majority is 18 years in most contexts, although the definition of majority may vary by legal rights and country. Human adulthood encompasses psychological adult development. Definitions of adulthood are often inconsistent and contradictory; an adolescent may be biologically an adult and display adult behavior but still be treated as

1600-404: The uterine tissue. The embryo, meanwhile, proliferates and develops both into embryonic and extra-embryonic tissue, the latter forming the fetal membranes and the placenta . In humans, the embryo is referred to as a fetus in the later stages of prenatal development. The transition from embryo to fetus is arbitrarily defined as occurring 8 weeks after fertilization. In comparison to the embryo,

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