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Puberty
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 testes in a boy. In response to 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. Before puberty, the external sex organs, known as primary sexual characteristics, are sex characteristics that distinguish boys and girls. Puberty leads to sexual dimorphism through the development of the secondary sex characteristics, which further distinguish the sexes. On average, girls begin puberty at ages 10–11 and complete puberty at ages 15–17; boys generally begin puberty at ages 11–12 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precocious Puberty
In medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. In a minority of children with precocious puberty, the early development is triggered by a disease such as a tumor or injury of the brain. Even when there is no disease, unusually early puberty can have adverse effects on social behavior and psychological development, can reduce adult height potential, and may shift some lifelong health risks. Central precocious puberty can be treated by suppressing the pituitary hormones that induce sex steroid production. The opposite condition is delayed puberty. The term is used with several slightly different meanings that are usually apparent from the context. In its broadest sense, and often simplified as early puberty, "precocious puberty" sometimes refers to any physical sex hormone effect, due to any cause, occurring ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenoestrogen
Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism. Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens. Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens". Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins. Xenoestrogens are clinically significant because they can mimic the effects of endogenous estrogen and thus have been implicated in precocious puberty and other disorders of the reproductive system. Xenoestrogens include pharmac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Development (biology)
Development of the human body is the process of growth to maturity. The process begins with fertilization, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The resulting zygote develops through mitosis and cell differentiation, and the resulting embryo then implants in the uterus, where the embryo continues development through a fetal stage until birth. Further growth and development continues after birth, and includes both physical and psychological development, influenced by genetic, hormonal, environmental and other factors. This continues throughout life: through childhood and adolescence into adulthood. Before birth Development before birth, or prenatal development () is the process in which a zygote, and later an embryo and then a fetus develops during gestation. Prenatal development starts with fertilization and the formation of the zygote, the first stage in embryonic development which continues in fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menarche
Menarche ( ; ) is the first menstrual cycle, or first menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fertility. Girls experience menarche at different ages. Having menarche occur between the ages of 9–16 in the west is considered normal.US National Health Statistics Report September 2020 Canadian psychological researcher Niva Piran claims that menarche or the perceived average age of puberty is used in many cultures to separate girls from activity with boys, and to begin confinement as a woman and future wife. The timing of menarche is influenced by female , as we ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adult
An adult is a human or other animal that has reached full growth. In human context, the term ''adult'' has meanings associated with social and legal concepts. In contrast to a " minor", a legal adult is a person who has attained the age of majority and is therefore regarded as independent, self-sufficient, and responsible. They may also be regarded as a "major". The typical age of attaining legal adulthood is 18, although definition may vary by legal rights, country, and psychological development. Human adulthood encompasses psychological adult development. Definitions of adulthood are often inconsistent and contradictory; a person may be biologically an adult, and have adult behavior, but still be treated as a child if they are under the legal age of majority. Conversely, one may legally be an adult but possess none of the maturity and responsibility that may define an adult character. In different cultures there are events that relate passing from being a child to becom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Child
A child ( : children) is a human being between the stages of birth and puberty, or between the developmental period of infancy and puberty. The legal definition of ''child'' generally refers to a minor, otherwise known as a person younger than the age of majority. Children generally have fewer rights and responsibilities than adults. They are classed as unable to make serious decisions. ''Child'' may also describe a relationship with a parent (such as sons and daughters of any age) or, metaphorically, an authority figure, or signify group membership in a clan, tribe, or religion; it can also signify being strongly affected by a specific time, place, or circumstance, as in "a child of nature" or "a child of the Sixties." Biological, legal and social definitions In the biological sciences, a child is usually defined as a person between birth and puberty, or between the developmental period of infancy and puberty. Legally, the term ''child'' may refer to anyone below ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Sex Characteristics
Secondary sex characteristics are features that appear during puberty in humans, and at sexual maturity in other animals. These characteristics are particularly evident in the sexually dimorphic phenotypic traits that distinguish the sexes of a species, but unlike the sex organs (primary sex characteristics), are not directly part of the reproductive system. Secondary sex characteristics are believed to be the product of sexual selection for traits which display fitness, giving an organism an advantage over its rivals in courtship and in aggressive interactions. Secondary sex characteristics include, for example, the manes of male lions, the bright facial and rump coloration of male mandrills, and horns in many goats and antelopes. These characteristics are believed to be produced by a positive feedback loop known as the Fisherian runaway produced by the secondary characteristic in one sex and the desire for that characteristic in the other sex. Male birds and fish of many speci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breast
The breast is one of two prominences located on the upper ventral region of a primate's torso. Both females and males develop breasts from the same embryological tissues. In females, it serves as the mammary gland, which produces and secretes milk to feed infants. Subcutaneous fat covers and envelops a network of ducts that converge on the nipple, and these tissues give the breast its size and shape. At the ends of the ducts are lobules, or clusters of alveoli, where milk is produced and stored in response to hormonal signals. During pregnancy, the breast responds to a complex interaction of hormones, including estrogens, progesterone, and prolactin, that mediate the completion of its development, namely lobuloalveolar maturation, in preparation of lactation and breastfeeding. Humans are the only animals with permanent breasts. At puberty, estrogens, in conjunction with growth hormone, cause permanent breast growth in female humans. This happens only to a much ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ejaculation
Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the male reproductory tract as a result of an orgasm. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. In rare cases, ejaculation occurs because of prostatic disease. Ejaculation may also occur spontaneously during sleep (a nocturnal emission or "wet dream"). '' Anejaculation'' is the condition of being unable to ejaculate. Ejaculation is usually very pleasurable for men; '' dysejaculation'' is an ejaculation that is painful or uncomfortable. Retrograde ejaculation is the condition where semen travels backwards into the bladder rather than out the urethra. Phases Stimulation A usual precursor to ejaculation is the sexual arousal of the male, leading to the erection of the penis, though not every arousal nor erection leads to ejaculation. Penile sexual stimulation during masturbation or vaginal, anal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Body
The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a head, hair, neck, trunk (which includes the thorax and abdomen), arms and hands, legs and feet. The study of the human body involves anatomy, physiology, histology and embryology. The body varies anatomically in known ways. Physiology focuses on the systems and organs of the human body and their functions. Many systems and mechanisms interact in order to maintain homeostasis, with safe levels of substances such as sugar and oxygen in the blood. The body is studied by health professionals, physiologists, anatomists, and by artists to assist them in their work. Composition The human body is composed of elements including hydrogen, oxygen, carbon, calcium and phosphorus. These elements reside in trillions of cells and non-cellula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, or behavioural or cognitive traits. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', which is when both biological sexes are phenotypically indistinguishable from each other. Overview Ornamentation and coloration Common and easily identified types of dimorphism consist of ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is called sexual dichromatism, which is commonly seen in many species of birds and reptiles. Sexual selection leads to the exaggerated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovary
The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. The ovaries also secrete hormones that play a role in the menstrual cycle and fertility. The ovary progresses through many stages beginning in the prenatal period through menopause. It is also an endocrine gland because of the various hormones that it secretes. Structure The ovaries are considered the female gonads. Each ovary is whitish in color and located alongside the lateral wall of the uterus in a region called the ovarian fossa. The ovarian fossa is the region that is bounded by the external iliac artery and in front of the ureter and the internal iliac artery. This area is about 4 cm x 3 cm x 2 cm in size.Daftary, Shirish; Chakravarti, Sudip (2011). Manual of Obstetrics, 3rd Edition. Elsevier. pp. 1-16. . The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
