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Teen Sex
Adolescent sexuality is a stage of human development in which adolescents experience and explore sexual feelings. Interest in sexuality intensifies during the onset of puberty, and sexuality is often a vital aspect of teenagers' lives. Sexual interest may be expressed in a number of ways, such as flirting, kissing, masturbation, or having sex with a partner. Sexual interest among adolescents, as among adults, can vary greatly, and is influenced by cultural norms and mores, sex education, as well as comprehensive sexuality education provided, sexual orientation, and social controls such as age-of-consent laws. Sexual activity in general is associated with various risks and this is heightened by the unfamiliar excitement of sexual arousal, the attention connected to being sexually attractive, and the new level of physical intimacy and psychological vulnerability created by sexual encounters. The risks of sexual intercourse include unwanted pregnancy and contracting a sexually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teenage Pregnancy
Teenage pregnancy, also known as adolescent pregnancy, is pregnancy in a female adolescent or young adult under the age of 20. This includes those who are legally considered adults in their country. The WHO defines adolescence as the period between the ages of 10 and 19 years. Pregnancy can occur with sexual intercourse after the start of ovulation, which can be before the first menstrual period (menarche) but usually occurs after the onset of periods. In well-nourished girls, the first period usually takes place around the age of 12 or 13. Pregnant teenagers face many of the same pregnancy related issues as other women. There are additional concerns for those under the age of 15 as they are less likely to be physically developed to sustain a healthy pregnancy or to give birth. For girls aged 15–19, risks are associated more with socioeconomic factors than with the biological effects of age. Risks of low birth weight, premature labor, anemia, and pre-eclampsia are not connec ... [...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 fetal develo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HIV/AIDS
Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual may not notice any symptoms, or may experience a brief period of influenza-like illness. Typically, this is followed by a prolonged incubation period with no symptoms. If the infection progresses, it interferes more with the immune system, increasing the risk of developing common infections such as tuberculosis, as well as other opportunistic infections, and tumors which are rare in people who have normal immune function. These late symptoms of infection are referred to as acquired immunodeficiency syndrome (AIDS). This stage is often also associated with unintended weight loss. HIV is spread primarily by unprotected sex (including anal and vaginal sex), contaminated blood transfusions, hypodermic needles, and from mother to ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hormone
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required for the correct development of animals, plants and fungi. Due to the broad definition of a hormone (as a signaling molecule that exerts its effects far from its site of production), numerous kinds of molecules can be classified as hormones. Among the substances that can be considered hormones, are eicosanoids (e.g. prostaglandins and thromboxanes), steroids (e.g. oestrogen and brassinosteroid), amino acid derivatives (e.g. epinephrine and auxin), protein or peptides (e.g. insulin and CLE peptides), and gases (e.g. ethylene and nitric oxide). Hormones are used to communicate between organs and tissues. In vertebrates, hormones are responsible for regulating a variety of physiological processes and behavioral activities such as diges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific American
''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it is the oldest continuously published magazine in the United States. ''Scientific American'' is owned by Springer Nature, which in turn is a subsidiary of Holtzbrinck Publishing Group. History ''Scientific American'' was founded by inventor and publisher Rufus Porter (painter), Rufus Porter in 1845 as a four-page weekly newspaper. The first issue of the large format newspaper was released August 28, 1845. Throughout its early years, much emphasis was placed on reports of what was going on at the United States Patent and Trademark Office, U.S. Patent Office. It also reported on a broad range of inventions including perpetual motion machines, an 1860 device for buoying vessels by Abraham Lincoln, and the universal joint which now can be found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuroimaging
Neuroimaging is the use of quantitative (computational) techniques to study the structure and function of the central nervous system, developed as an objective way of scientifically studying the healthy human brain in a non-invasive manner. Increasingly it is also being used for quantitative studies of brain disease and psychiatric illness. Neuroimaging is a highly multidisciplinary research field and is not a medical specialty. Neuroimaging differs from neuroradiology which is a medical specialty and uses brain imaging in a clinical setting. Neuroradiology is practiced by radiologists who are medical practitioners. Neuroradiology primarily focuses on identifying brain lesions, such as vascular disease, strokes, tumors and inflammatory disease. In contrast to neuroimaging, neuroradiology is qualitative (based on subjective impressions and extensive clinical training) but sometimes uses basic quantitative methods. Functional brain imaging techniques, such as functional magnet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macmillan Higher Education
Macmillan Publishers (occasionally known as the Macmillan Group; formally Macmillan Publishers Ltd and Macmillan Publishing Group, LLC) is a British publishing company traditionally considered to be one of the 'Big Five' English language publishers. Founded in London in 1843 by Scottish brothers Daniel and Alexander MacMillan, the firm would soon establish itself as a leading publisher in Britain. It published two of the best-known works of Victorian era children’s literature, Lewis Carroll's ''Alice's Adventures in Wonderland'' (1865) and Rudyard Kipling's ''The Jungle Book'' (1894). Former Prime Minister of the United Kingdom, Harold Macmillan, grandson of co-founder Daniel, was chairman of the company from 1964 until his death in December 1986. Since 1999, Macmillan has been a wholly owned subsidiary of Holtzbrinck Publishing Group with offices in 41 countries worldwide and operations in more than thirty others. History Macmillan was founded in London in 1843 by Daniel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Brain
The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head. The cerebrum, the largest part of the human brain, consists of two cerebral hemispheres. Each hemisphere has an inner core composed of white matter, and an outer surface – the cerebral cortex – composed of grey matter. The cortex has an outer layer, the neocortex, and an inner allocortex. The neocortex is made up of six neuronal layers, while the allocortex has three or four. Each hemisphere is conventionally divided into four lobes – the frontal, temporal, parietal, and occipital lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prefrontal Cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, and BA47. The basic activity of this brain region is considered to be orchestration of thoughts and actions in accordance with internal goals. Many authors have indicated an integral link between a person's will to live, personality, and the functions of the prefrontal cortex. This brain region has been implicated in executive functions, such as planning, decision making, short-term memory, personality expression, moderating social behavior and controlling certain aspects of speech and language. Executive function relates to abilities to differentiate among conflicting thoughts, determine good and bad, better and best, same and different, future consequences of current activities, working toward a defined goal, prediction of outcomes, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothalamus
The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is part of the limbic system. In the terminology of neuroanatomy, it forms the ventral part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is the size of an almond. The hypothalamus is responsible for regulating certain metabolic processes and other activities of the autonomic nervous system. It synthesizes and secretes certain neurohormones, called releasing hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of hormones from the pituitary gland. The hypothalamus controls body temperature, hunger, important aspects of parenting and maternal attachment behaviours, thirst, fatigue, sleep, and circadian rhythms. Structure T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebral Cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of allocortex. It is separated into two cortices, by the longitudinal fissure that divides the cerebrum into the left and right cerebral hemispheres. The two hemispheres are joined beneath the cortex by the corpus callosum. The cerebral cortex is the largest site of neural integration in the central nervous system. It plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The cerebral cortex is part of the brain responsible for cognition. In most mammals, apart from small mammals that have small brains, the cerebral cortex is folded, providing a greater surface area in the confined volume of the cranium. Apart from minimising brain and cranial volume, cortical folding is crucial for the brain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frontal Lobe
The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove between tissues called the central sulcus and from the temporal lobe by a deeper groove called the lateral sulcus (Sylvian fissure). The most anterior rounded part of the frontal lobe (though not well-defined) is known as the frontal pole, one of the three poles of the cerebrum. The frontal lobe is covered by the frontal cortex. The frontal cortex includes the premotor cortex, and the primary motor cortex – parts of the motor cortex. The front part of the frontal cortex is covered by the prefrontal cortex. There are four principal gyri in the frontal lobe. The precentral gyrus is directly anterior to the central sulcus, running parallel to it and contains the primary motor cortex, which controls voluntary movements of specific body parts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
