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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] |
Vellus Hair
Vellus hair is short, thin, light-colored, and barely noticeable hair that develops on most of a human’s body during childhood. Exceptions include the lips, the back of the ear, the palm of the hand, the sole of the foot, some external genital areas, the navel, and scar tissue. The density of hair – the number of hair follicles per area of skin – varies from person to person. Each strand of vellus hair is usually less than 2 mm (1/13 inch) long and the follicle is not connected to a sebaceous gland. Vellus hair is most easily observed on children and adult women, who generally have less terminal hair to obscure it. Vellus hair is not lanugo hair. Lanugo hair is a much thicker type of hair that normally grows only on fetuses. Vellus hair is differentiated from the more visible terminal or androgenic hair, which develops only during and after puberty, usually to a greater extent on men than it does on women. The Latin language uses the word ''vellus'' to designate "a fleec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 and complete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Axillary 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] |
Secondary Sex Characteristic
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 species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facial Hair
Facial hair is hair grown on the face, usually on the chin, cheeks, and upper lip region. It is typically a secondary sex characteristic of human males. Men typically start developing facial hair in the later stages of puberty or adolescence, around fifteen years of age, and most do not finish developing a full adult beard until around eighteen or later. Large variations can occur however, as boys as young as eleven have been known to develop facial hair, and some men do not produce much facial hair at all. Men may style their facial hair into beards, moustaches, goatees or sideburns; many others completely shave their facial hair and this is referred to as being "clean-shaven". The term ''whiskers'', when used to refer to human facial hair, indicates the hair on the chin and cheeks. Women are also capable of developing facial hair, especially after menopause, though typically significantly less than men. Women with lots of facial hair, the extreme being bearded ladies, hav ... [...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] |
Abdominal Hair
Abdominal hair is the hair that grows on the abdomen of humans and non-human mammals, in the region between the pubic area and the thorax (chest). The growth of abdominal hair follows the same pattern on nearly all mammals, vertically from the pubic area upwards and from the thorax downwards to the navel. The abdominal hair of non-human mammals is part of the pelage, (hair or fur). It connects pubic hair and chest hair. In humans Before puberty, the abdominal region of both males and females is covered with very fine vellus hair. In response to rising levels of androgens (mainly testosterone) during and after puberty, the skin of the abdomen begins to produce coarser, longer and more pigmented hair (terminal hair). This process primarily affects men. Initially hair grows in a vertical line from the pubic area up to the navel and from the thorax down to the navel. Although the development of abdominal hair normally begins during puberty, it may also start later, between the age ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leg Hair
Leg hair is hair that grows on the legs of humans, generally appearing after the onset of puberty. For aesthetic reasons and for some sports, people shave, wax, epilate, or use hair removal creams to remove the hair from their legs: see leg shaving. The current Guinness World Record for world's longest leg hair belongs to Jason Allen of Tucson, Arizona at 8.84 inches (22.46 cm). Growth The real action of leg hair takes place below the skin or the epidermis. The cells that are in the hair follicles divide and multiply. When the space fills up in the follicle it pushes older cells out and that is what becomes the leg hair. After the older cells become hard and leave the follicle, they form a hair shaft. The hair shaft is mostly made up of dead tissue and a protein that is known as keratin. It is said that hair growth occurs during the "growing" phase of the follicle, and then retained as dead club hair during the "resting" phase. The old club hair might be lost within th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arm Hair
Body hair, or androgenic hair, is the terminal hair that develops on the human body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which is much finer and lighter in color. The growth of androgenic hair is related to the level of androgens (often referred to as male hormones) and the density of androgen receptors in the dermal papillae. Both must reach a threshold for the proliferation of hair follicle cells. From childhood onward, regardless of sex, vellus hair covers almost the entire area of the human body. Exceptions include the lips, the backs of the ears, palms of hands, soles of the feet, certain external genital areas, the navel, and scar tissue. The density of hair – i.e. the number of hair follicles per unit area of skin – varies from person to person. In many cases, areas on the human body that contain vellus hair will begin to produce darker and thicker body hair during puberty, such as the first growth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foot Hair
Body hair, or androgenic hair, is the terminal hair that develops on the human body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which is much finer and lighter in color. The growth of androgenic hair is related to the level of androgens (often referred to as male hormones) and the density of androgen receptors in the dermal papillae. Both must reach a threshold for the proliferation of hair follicle cells. From childhood onward, regardless of sex, vellus hair covers almost the entire area of the human body. Exceptions include the lips, the backs of the ears, palms of hands, soles of the feet, certain external genital areas, the navel, and scar tissue. The density of hair – i.e. the number of hair follicles per unit area of skin – varies from person to person. In many cases, areas on the human body that contain vellus hair will begin to produce darker and thicker body hair during puberty, such as the first grow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
