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Pubic Hair
Pubic hair is terminal body hair that is found in the genital area of adolescent and adult humans. The hair is located on and around the sex organs and sometimes at the top of the inside of the thighs. In the pubic region around the pubis bone, it is known as a ''pubic patch''. Pubic hair is also found on the scrotum in the male and on the vulva in the female. Although fine vellus hair is present in the area in childhood, pubic hair is considered to be the heavier, longer and coarser hair that develops during puberty as an effect of rising levels of androgens in males and estrogens in females. Pubic hair differs from other hair on the body and is a secondary sex characteristic. Many cultures regard pubic hair as erotic, and in most cultures it is associated with the genitals, which both men and women are expected to keep covered at all times. In some cultures, it is the norm for pubic hair to be removed, especially of females; the practice is regarded as part of personal hygie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal Hair
In humans, terminal hair is a variant of hair that is thick and long such as what grows on the scalp, as compared with vellus hair, colloquially known as peach fuzz, growing elsewhere.Marks, James G; Miller, Jeffery (2006)''Lookingbill and Marks' Principles of Dermatology''(4th ed.), Elsevier Inc., p. 11. During puberty, the increase in androgenic hormone levels causes vellus hair to be replaced with terminal hair in certain parts of the human body.Hiort, O. "Androgens and Puberty". ''Best Practice & Research Clinical Endocrinology & Metabolism'', Vol. 16, No. 1, pp. 31–41. These parts will have different levels of sensitivity to androgens, primarily of the testosterone family.Neal, Matthew; Lauren M. Sompayrac''How the Endocrine System Works'' Blackwell Publishing, 2001, p. 75. The pubic area is particularly sensitive to such hormones, as are the armpits which will develop axillary hair.Randall, Valerie A.; Nigel A. Hibberts, M. Julie Thornton, Kazuto Hamada, Alison E. Mer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sex Hormones
Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors. The sex hormones include the androgens, estrogens, and progestogens. Their effects are mediated by slow genomic mechanisms through nuclear receptors as well as by fast nongenomic mechanisms through membrane-associated receptors and signaling cascades. The polypeptide hormones luteinizing hormone, follicle-stimulating hormone and gonadotropin-releasing hormone – each associated with the gonadotropin axis – are usually not regarded as sex hormones, although they play major sex-related roles. Production Natural sex hormones are made by the gonads (ovaries or testes), by adrenal glands, or by conversion from other sex steroids in other tissue such as liver or fat. Image:Steroidogenesis.svg Image:Biosinthesis of steroid hormones (simplified version).jpg Image:Biosinthesis of steroid hormones (extended version).jpg Ima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Race (human Classification)
A race is a categorization of humans based on shared physical or social qualities into groups generally viewed as distinct within a given society. The term came into common usage during the 1500s, when it was used to refer to groups of various kinds, including those characterized by close kinship relations. By the 17th century, the term began to refer to physical (phenotypical) traits, and then later to national affiliations. Modern science regards race as a social construct, an identity which is assigned based on rules made by society. While partly based on physical similarities within groups, race does not have an inherent physical or biological meaning. The concept of race is foundational to racism, the belief that humans can be divided based on the superiority of one race over another. Social conceptions and groupings of races have varied over time, often involving folk taxonomies that define essential types of individuals based on perceived traits. Today, scientists con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyebrows
An eyebrow is an area of short hairs above each eye that follows the shape of the lower margin of the brow ridges of some mammals. In humans, eyebrows serve two main functions: first, communication through facial expression, and second, prevention of sweat, water, and other debris from falling down into the eye socket. It is common for people to modify their eyebrows by means of hair removal and makeup. Functions A number of theories have been proposed to explain the function of the eyebrow in humans. One approach suggests its main function is to prevent moisture (mostly sweat and rain) from flowing into the eye. Another theory holds that clearly visible eyebrows provided safety from predators when early hominid groups started sleeping on the ground. Recent research, however, suggests eyebrows in humans developed as a means of communication and that this is their primary function. Humans developed a smooth forehead with visible, hairy eyebrows capable of a wide range of movemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underarm Hair
Underarm hair, also known as axillary hair, is the hair in the underarm area (''axilla''). Development Underarm or axillary hair goes through four stages of development, driven by weak androgens produced by the adrenal in males and females during adrenarche, and testosterone from the testicle in males during puberty. The importance of human underarm hair is unclear. It may naturally wick sweat or other moisture away from the skin, aiding ventilation. Colonization by odor-producing bacteria is thereby transferred away from the skin (see skin flora). File:Armpit by David Shankbone.jpg , Male axilla File:Womans armpit.JPG , Female axilla Function Reducing friction Armpit hair prevents skin-to-skin contact during activities that involve arm motion, such as running and walking. The same applies to pubic hair. Spreading pheromones The armpits release odor-containing pheromones, a naturally produced chemical that plays an important role in sexual attraction. Armpit hair tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testis
A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testosterone. Testosterone release is controlled by the anterior pituitary luteinizing hormone, whereas sperm production is controlled both by the anterior pituitary follicle-stimulating hormone and gonadal testosterone. Structure Appearance Males have two testicles of similar size contained within the scrotum, which is an extension of the abdominal wall. Scrotal asymmetry, in which one testicle extends farther down into the scrotum than the other, is common. This is because of the differences in the vasculature's anatomy. For 85% of men, the right testis hangs lower than the left one. Measurement and volume The volume of the testicle can be estimated by palpating it and comparing it to ellipsoids of known sizes. Another method is to use caliper ... [...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 ovari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonad
A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells. Both of these gametes are haploid cells. Some hermaphroditic animals have a type of gonad called an ovotestis. Evolution It is hard to find a common origin for gonads, but gonads most likely evolved independently several times. Regulation The gonads are controlled by luteinizing hormone and follicle-stimulating hormone, produced and secreted by gonadotropes or gonadotrophins in the anterior pituitary gland. This secretion is regulated by gonadotropin-releasing hormone produced in the hypothalamus. Development Gonads start developing as a common primordium (an organ in the earliest stage of development), in the form of genital ridges, which are only l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beard
A beard is the hair that grows on the jaw, chin, upper lip, lower lip, cheeks, and neck of humans and some non-human animals. In humans, usually pubescent or adult males are able to grow beards. Throughout the course of history, societal attitudes toward male beards have varied widely depending on factors such as prevailing cultural-religious traditions and the current era's fashion trends. Some religions (such as some sects of Islam, and Sikhism) have considered a full beard to be essential and mandate it as part of their observance. Other cultures, even while not officially mandating it, view a beard as central to a man's virility, exemplifying such virtues as wisdom, strength, sexual prowess and high social status. In cultures where facial hair is uncommon (or currently out of fashion), beards may be associated with poor hygiene or an unconventional demeanor. In countries with colder climates, beards help protect the wearer's face from the elements. Beards also provide sun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chest Hair
Chest hair is hair that grows on the chest in the region between the neck and the abdomen. Chest hair develops during and after puberty along with other types of androgenic hair. Development and growth Although vellus hair is already present in the area in childhood, chest hair is the terminal hair that develops as an effect of rising levels of androgens (primarily testosterone and its derivatives) due to puberty. Different from the head hair, it is therefore a secondary sexual characteristic. Men tend to be covered with far more terminal hair, particularly on the chest, the abdomen, and the face. The development of chest hair begins normally during late puberty, usually between the ages of 12 and 18. It can also start later, between the age of 20 and 30, so that many men in their twenties have not yet reached their full chest hair development. The growth continues subsequently. Patterns and characteristics The individual occurrence and characteristics of chest hair depend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nipple
The nipple is a raised region of tissue on the surface of the breast from which, in females, milk leaves the breast through the lactiferous ducts to feed an infant. The milk can flow through the nipple passively or it can be ejected by smooth muscle contractions that occur along with the ductal system. The nipple is surrounded by the areola, which is often a darker colour than the surrounding skin. A nipple is often called a teat when referring to non-humans. Nipple or teat can also be used to describe the flexible mouthpiece of a baby bottle. In humans, the nipples of both males and females can be stimulated as part of sexual arousal. In many cultures, human female nipples are sexualized, or "regarded as sex objects and evaluated in terms of their physical characteristics and sexiness." Anatomy In mammals, a nipple (also called mammary papilla or teat) is a small projection of skin containing the outlets for 15–20 lactiferous ducts arranged cylindrically around the tip. Ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axilla
The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superiorly by the imaginary plane between the superior borders of the first rib, clavicle and scapula (above which are considered part of the neck), medially by the serratus anterior muscle and thoracolumbar fascia, anteriorly by the pectoral muscles and posteriorly by the subscapularis, teres major and latissimus dorsi muscle. The soft skin covering the lateral axilla contains many hair and sweat glands. In humans, the formation of body odor happens mostly in the axilla. These odorant substances have been suggested by some to serve as pheromones, which play a role related to mate selection, although this is a controversial topic within the scientific community. The underarms seem more important than the pubic area for emitting body odor, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
