Puberty

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Puberty is the sexual development of children that makes them adults. This makes their bodies change.

Puberty is the sexual development of children into adults. A girl at puberty can become pregnant, a boy if he has sex with a girl can make her pregnant. Changes that occur to both sexes at puberty include sex organs growing and secondary sex characteristics,such as boys' voices getting deeper, and girls' breast growth. People in puberty become sexually attracted to each other.

How the body controls puberty[change | change source]

The location of the pituitary gland is in orange. The gland makes hormones that cause both sexes' bodies to start puberty.

Puberty is begun and carried on by different hormones, chemicals that tell parts of the body to do things. Hormones are made by glands in the body. Glands are organs (special parts) of the body that make hormones. This process occurs at puberty:[1]

  1. A gland at the bottom of the brain called the hypothalamus sends gonadotropin-releasing hormone (GnRH) into a nearby gland called the pituitary gland.
  2. GnRH causes cells in the pituitary gland to make 2 hormones, luteinizing hormone (LH) and follicle stimulating hormone (FSH).[2] LH and FSH are types of hormones called gonadotropins. The bloodstream carries these hormones around the body.
  3. LH and FSH make the gonads grow larger and start producing their own hormones,estradiol and testosterone. A girl's gonads are her ovaries, and a boy's gonads are his testicles (also called testes). Both ovaries and testicles produce estradiol and testosterone, but ovaries produce more estradiol and testicles produce more testosterone. Estradiol and testosterone are types of hormones called steroid hormones. Steroid hormones are also made by the body's 2 adrenal glands, which sit on top of the 2 kidneys.
  4. When the amount of estradiol and testosterone in the body increases, various body parts change.

When puberty starts and ends[change | change source]

Puberty usually begins sooner in girls than in boys.[3]Usually, girls begin puberty at age 10; boys at 11–12.[4][5] [6]Girls usually complete puberty by 15,[7] boys by 16.[5][8] But this varies.[9]The major landmark of puberty for females is menarche(onset of menstruation), which occurs mostly at 12–13;[10][11][12] for males, it is the first ejaculation,which occurs mostly at 13.[13] In the 2000s, the average age when children, especially girls, hit puberty is lower than in the 1800s, due to improved eating.[14]

Body changes in males[change | change source]

For most boys, puberty takes place at ages 11-16. At the end of puberty, a boy is usually about 10-30 centimetres taller, 7 to 29 kilograms heavier, and stronger. He is able to make women pregnant.[15]

Sex organs grow bigger[change | change source]

The first sign of puberty in boys is that their testicles (also called testes) and scrotum (where the testicles are) grow bigger.[16] Before puberty, each testicle is about 1.5-2 cm long and has a volume of about 2-3 cubic centimetres. About 6 years after puberty starts, the testicles reach their adult size.[17] The volume of an average adult man's testicle is about 18-20 cc. However, it is normal for some men to have testicles smaller than this size, and for other men to have larger testicles.[18]

The penis also grows bigger at puberty. At the start of puberty, the average length of the penis is 6 cm (2.4 in). The penis reaches adult size about 5 years later.[19] A study done in 1996 found the mean length of an adult man's penis is 3.5 in (8.9 cm) when it is flaccid (pronounced FLA-sid) (not erect or hard).[20] The average length of an erect penis is about 12.9-15 cm. [20][21]

The testicles have 2 main jobs: making hormones and sperm. The testicles make the hormone testosterone, which spreads around the body. This causes the changes in the body that make a boy become a man. Testosterone also makes a man desire sex. 1 year after puberty begins, when boys urinate after waking up in the morning, sperm is in the urine. When a boy is about 13 years old his testicles will have grown to the stage that he may be fertile (able to make a woman pregnant). The sperm in the testicles mixes with other liquids in the body to form a whitish or yellowish and sticky fluid called semen. At puberty, 2 glands in the body called the seminal vesicles and prostate also grow bigger.[22] These glands make a lot of the liquid that is in semen.

When a man is sexually excited, he has an erection – his penis becomes bigger, longer and harder. A male becomes sexually excited if thinks about sex or sees a good-looking person, or if he masturbates. At puberty, boys also have erections for no reason.[23]

When a man's penis is sexually stimulated for some time, he has ejaculates, has an orgasm and semen shoots out from the penis. A boy's first ejaculation usually happens about one year after he begins puberty. For some boys, the first ejaculation takes place when they are sleeping. This is called a nocturnal emission or a wet dream. It happens without the boy's control, often when he is having a dream about sex. Scientists think wet dreams are the body's way of removing too much semen. A male masturbates when he rubs his penis to make himself feel good sexually. A 2004 magazine survey in Canada found that 43% started masturbating when they were about 12-13 years old.[24] When boys start masturbating, wet dreams often stop since semen is taken out from his body regularly.

When a boy starts to ejaculate, he usually produces only a small amount of semen. The semen is different from what an adult man produces. It is usually clear and stays sticky. It either has no sperm in it, or sperm that do not move properly or at all. A boy's semen only becomes like an adult man's semen about 2 years after his first ejaculation.[25]

Body hair and skin changes[change | change source]

This picture shows hair growth on the male body at and after puberty.
The face starts growing hair during puberty.

Soon after a boy's testicles and penis start to grow, pubic hair (pronounced PEW-bik) appears. Pubic hair grows in the pubic region, which is the part of the body where the penis is. Pubic hair is shorter, curlier and rougher than the head's hair. It usually starts growing on the abdomen above the penis where it joins the body. (The abdomen is the part of the torso where the navel is.) There may be some hair on the scrotum. After about 6 months-1 year, there will be a large triangle of hair in the pubic region. Within 3-4 years after puberty begins, there is a lot of pubic hair in the area above the penis. Later on, pubic hair also grows on the abdomen upwards towards the navel and on the insides of the thighs.[26]

About 2 years after pubic hair starts to appear,[26] hair also grows on other parts of the body, the armpits, around the anus, the top lip, making a mustache, the sides of the face next to the ears, making sideburns, around the nipples, and the lower part of the face, making beard.

The hair on the arms, legs, chest, abdomen and back may also become thicker. Different men have different amounts of body hair. Most boys begin shaving when hair starts growing on their faces.

A larger amount of male hormones in the body cause sweating,which gives it a more adult smell. The hormones also cause sebaceous glands in the skin to make more sebum, a type of oil that keeps skin from getting too dry. Sebum and dead skin cells can mix with a type of germ called bacteria and block pores (tiny openings) in the skin. This causes a skin problem called acne. Most people get acne at puberty. When a person has acne, he gets swellings on his skin called blackheads, whiteheads and pimples. Blackheads and whiteheads are painless, but pimples can be painful. They usually form on the face but can also appear on the neck, shoulders, upper back and chest. Oil glands on scalp – the part of the head on which hair grows – also make a lot of sebum. This can cause dandruff, in which small white bits of skin fall from the scalp.[27]

Voice changes[change | change source]

During puberty, a boy's voicebox grows larger. This makes the Adam's apple – the lump that sticks out of the front of his neck – larger. As the voicebox grows the vocal cords become longer and thicker, they vibrate (move back and forth) slower. This causes the voice to lower in pitch and become deeper. When this happens, it is sometimes said that the boy's voice has "broken". However, it actually does not happen overnight but over time. On average, a boy's voice normally reaches its adult sound when he is about 15 years old.[28]

Body growth[change | change source]

Towards the end of puberty,a boys have a growth spurt (grow taller) for about 2-3 years. When the growth spurt is fastest, some people grow 10 cm or more a year. This happens about 2 years after puberty starts, usually from ages 13-15. When a boy reaches the end of his growth spurt he is about 18 years, and of adult height. He will not grow much taller.[1][29]

Boys grow slower than girls, but for longer. Thus most men are taller than women.[29] By puberty's end, men have heavier bones and more muscle than women. In an average adult man, muscle makes up 50% and fat 15% of his weight. On the other hand, 40% of an average adult woman's weight is made up of muscle while 27% is made up of fat. Because men have less body fat than women, their hips do not grow bigger. Some bones like those in the jaw and shoulders grow more in males than in females. That is why males have wider faces and shoulders but narrower hips.[30]

Body changes in females[change | change source]

The changes in a girl's body during puberty usually take place during ages 8-15 years. After puberty,they have breasts and pubic hair, menstruate every month,and can get pregnant. They usually also have reached their full adult height.[31]

Breasts Grow[change | change source]

Thelarche is when girls grow breasts[32], and is normally the first sign of puberty that can be seen on the outside of a girl's body. This usually begins when girls are about 9[33]. A lump that is a bit hard appears in each breast under the areola, which is the dark ring around the nipple. The lump in one breast may grow before the other one.[34] This is called breast budding.[35] Within 6-12 months, both breasts will have started growing. The swelling can be felt and seen outside the edges of the areolae. About 1 and a half to 2 years after the breasts first start growing, they are close to the shape and size of an adult woman's breasts. The nipple and areola may be on a smaller mound on each breast. This small mound usually goes away when each breast is fully grown.[36] Breast size depends on the body's amount of fat.[35][37]

Body hair and skin changes[change | change source]

The brown parts of the picture on the left show where hair grows on a woman's body. Thicker hair is shown by the dark brown parts, and thinner hair by the light brown parts. As you can see from the picture on the right, men generally have more body hair than women.

At about age 8-14, pubic hair begins to grow along the labia (the "lips" of the vulva), usually a few months after the breasts start growing.[36][38] At first the hair is thin and straight instead of curly, and there is not much of it.[31][38] Within a year, the pubic hair becomes rough, dark and curly and grows in a triangle shape in the pubic region. About one year after pubic hair begins appearing, underarm hair also grows. The hair on the arms and legs also gets thicker, and some girls may have hair appearing on their upper lip and in front of their ears.[39] Like boys, higher amounts of hormones in the body cause girls' sweat to change. This gives them a more adult body smell. The hormones also cause the skin to produce more oil, which usually causes acne.

Changes to the sex organs and menstruation[change | change source]

When girls are 8-11 years old, the 2 ovaries in their body begin to grow bigger.[31] Each ovary is egg-shaped, and is attached to the side wall of the pelvis. The pelvis is a large set of bones in the hips. The ovaries are organs that make female hormones. These hormones cause a girl to grow into a woman, and make her feel like a woman. The hormones also make it possible for females to become pregnant and have babies. Inside the ovaries are about 200,000 ova (egg cells).[40] For a baby to be formed, a woman's ovum and a man's sperm must come together. At puberty, the ova also grow bigger.[41]

Between the ages of 9-15 years, the vagina and uterus (womb) become bigger.[31][41] The uterus is the organ in which a baby grows. The vagina is a tube leading from the uterus to the outside of the body. The opening of the vagina is inside the vulva, in between the legs. A clear or whitish fluid may start to flow out of the vagina to keep it clean.[34] Then, about 2 years after the breasts start to grow,[42] when a girl is 10-16 years old, hormones made by her ovaries cause the ovaries to release an ovum, which moves into the uterus. Usually, only one ovum is released at a time. The hormones also tell the uterus to get ready for a baby, in case the ovum meets a sperm and gets fertilized. The walls of the uterus become thicker with extra tissue. Inside the thick part of the uterus are blood vessels and other nutrients that a baby will need to grow. If an ovum in the uterus gets fertilized, it sticks to the wall of the uterus and starts to grow. However, if the ovum is not fertilized, it does not stick. The uterus then gets rid of the ovum and the extra tissue by releasing it from the body. The tissue and blood flows out of the uterus through the vagina. This is called menstruation or having a period. The bleeding normally lasts about 3-5 days, though some girls may bleed longer or have a bit of bleeding between periods.[43] The uterus then starts preparing for another ovum. For most girls, the time between their periods is about one month. For about 2 years after menstruation starts, the time between periods is not always the same.[44] Some girls may skip a month, or have 2 periods close to each other. It is also normal to have cramps (rather painful squeezing feelings) or to feel bloated (swollen up) in the abdomen at periods.[43] When many girls start having periods, they begin using sanitary napkins or tampons to soak up the blood and tissue. A sanitary napkin is a piece of material that absorbs (takes in) liquids which is worn between the vulva and underpants. A tampon is a stick of absorbent material that is placed in the vagina.

Body growth[change | change source]

Because of more hormones in the body, girls start to have more fat in their breasts, abdomen, hips and thighs. At 10 years, the average girl has 6% more body fat than the average boy, but by the end of puberty she has 50% more.[45] The fat ensures a baby inside a pregnant woman has enough nutrients. Also, the bones in the pelvis move further apart to make room for a larger uterus and ovaries, and so there is space for a baby to grow in the uterus and to pass out of the body when born. The extra fat and wider hip bones girls have give them a curvier shape.[46] Girls also experience a growth spurt at puberty that usually ends about age 17 years. [47] In the first year after puberty begins, they grow about 8 cm. They grow even faster the next year or so, then the growth slows down and almost stops when they start menstruating. After a girl's periods begin, she usually does not grow more than 5 cm taller.[39]

References[change | change source]

  1. 1.0 1.1 Steven Dowshen (reviewer) (April 2007). "Everything you wanted to know about puberty". TeensHealth, The Nemours Foundation's Center for Children's Health Media. http://kidshealth.org/teen/sexual_health/changing_body/puberty.html. Retrieved 29 November 2008.
  2. T.M. Plant (January 2001). "Leptin, Growth Hormone, and the Onset of Primate Puberty". J. Clin. Endocrinol. Metab. 86 (1): 458–460. http://www.ncbi.nlm.nih.gov/pubmed/11232044.
  3. http://www.pamf.org/parenting-teens/health/growth-development/pre-growth.html
  4. "When is puberty too early?". Duke University Hospital. http://www.dukehealth.org/health_library/advice_from_doctors/your_childs_health/when-is-puberty-too-early. Retrieved October 10, 2012.
  5. 5.0 5.1 "For girls, puberty begins around 10 or 11 years of age and ends around age 16. Boys enter puberty later than girls-usually around 12 years of age-and it lasts until around age 16 or 17." "Teenage Growth & Development: 11 to 14 Years". pamf.org. http://www.pamf.org/teen/parents/health/growth-11-14.html.
  6. Solway, Andrew Exercise: From Birth to Old Age page 26
  7. Jaclyn McComb, Mimi Zumwait, Reid Norman The Active Female Health Issues Throughout the Life Span page 223
  8. "Teenage Growth & Development: 15 to 17 Years". pamf.org. http://www.pamf.org/teen/parents/health/growth-15-17.html.
  9. A.J. Giannini; A.E. Slaby (1981). "A Speculation on Oranges, Puberty, Marriage Contracts and Frozen Food". M.D. 25 (5): 51–52.
  10. Anderson SE, Dallal GE, Must A (2003). "Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart". Pediatrics 111 (4 Pt 1): 844–50. doi:10.1542/peds.111.4.844 . PMID 12671122 .
  11. Al-Sahab B, Ardern CI, Hamadeh MJ, Tamim H (2010). "Age at menarche in Canada: results from the National Longitudinal Survey of Children & Youth". BMC Public Health (BMC Public Health) 10: 736. doi:10.1186/1471-2458-10-736 . PMC 3001737 . PMID 21110899 .
  12. Hamilton-Fairley, Diana. Obstetrics and Gynaecology (Second ed.). Blackwell Publishing. http://vstudentworld.yolasite.com/resources/final_yr/gynae_obs/Hamilton%20Fairley%20Obstetrics%20and%20Gynaecology%20Lecture%20Notes%202%20Ed.pdf.
  13. (Jorgensen & Keiding 1991).
  14. Guillette EA et al (2006). "Altered breast development in young girls from an agricultural environment". Environ. Health Perspect. 114 (3): 471–5. PMC 1392245 . PMID 16507474 .
  15. Ann Byers (2007). "How Do Boys' Bodies Change during Puberty?". Frequently Asked Questions about Puberty. New York, N.Y.: Rosen Publishing. pp. 16–25 at 16. ISBN 978-1-4042-0966-4 .
  16. Dennis M. Styne (2002). M.A. Sperling. ed. Pediatric Endocrinology (2nd ed. ed.). Philadelphia, Pa.: Saunders. p. 598. ISBN 9780721695396 .
  17. Kenneth W. Jones (2006). Smith's Recognizable Patterns of Human Malformation. St. Louis, Mo.: Elsevier Saunders. ISBN 9780721606156 .
  18. Marshall, Human Growth, p. 180.
  19. W.A. Schonfeld (1943). "Primary and Secondary Sexual Characteristics: Study of their Development in Males from Birth through Maturity, with Biometric Study of Penis and Testes". American Journal of Diseases of Children 65: 535.
  20. 20.0 20.1 H. Wessells H; T.F. Lue; J.W. McAninch (1996). "Penile Length in the Flaccid and Erect States: Guidelines for Penile Augmentation". Journal of Urology 156 (3): 995–997. doi:10.1016/S0022-5347(01)65682-9 .
  21. See also J. Chen; A. Gefen; A. Greenstein; H. Matzkin; D. Elad (2000). "Predicting Penile Size during Erection". International Journal of Impotence Research 12 (6): 328–333. doi:10.1038/sj.ijir.3900627 . "Ansell Research: The penis size survey". Ansell Healthcare. March 2001. http://www.free-condom-stuff.com/education/research.htm. Retrieved 29 November 2008.
  22. Steve Dowshen (reviewer) (November 2007). "Male reproductive system". TeensHealth, The Nemours Foundation's Center for Children's Health Media. http://kidshealth.org/teen/sexual_health/changing_body/male_repro.html. Retrieved 29 November 2008.
  23. Byers, Frequently Asked Questions about Puberty, p. 23.
  24. Alice Klein (2004). "Love & Sex Guide". Now. http://www.nowtoronto.com/minisites/loveandsex/2004/s_survey_results.php. Retrieved 2 May 2010.
  25. Z. Janczewski; L. Bablok (1985). "Semen Characteristics in Pubertal Boys: I. Semen Quality after First Ejaculation". Archives of Andrology 15: 199–205. http://www.ncbi.nlm.nih.gov/pubmed/3833078.
  26. 26.0 26.1 Byers, Frequently Asked Questions about Puberty, p. 18.
  27. Byers, Frequently Asked Questions about Puberty, pp. 22–23.
  28. Byers, Frequently Asked Questions about Puberty, pp. 21–22.
  29. 29.0 29.1 Byers, Frequently Asked Questions about Puberty, p. 19.
  30. Byers, Frequently Asked Questions about Puberty, p. 21.
  31. 31.0 31.1 31.2 31.3 J. Jeff Malta. "5 stages of puberty – girls?". Puberty 101. http://www.puberty101.com/p_pubgirls.shtml. Retrieved 1 December 2008.
  32. http://dictionary.reference.com/browse/thelarche
  33. Olson, Ginny Teenage Girls: Exploring Issues Adolescent Girls Face and Strategies to help them https://books.google.com/books?id=miQ5iJnXDKkC&pg=PT30&dq=girls+breasts+start+growing+10+years&hl=en&sa=X&ei=YhDgVKffF4qmyAT6q4CgDQ&ved=0CB0Q6AEwAA#v=onepage&q&f=false
  34. 34.0 34.1 Marshall, Human Growth, p. 187.
  35. 35.0 35.1 Anne Byers (2007). "How do Girls' Bodies Change during Puberty?". Frequently Asked Questions about Puberty. New York, N.Y.: Rosen Publishing. pp. 26–33 at 27. ISBN 978-1-4042-0966-4 ..
  36. 36.0 36.1 Marshall, Human Growth, p. 188.
  37. See also "Normal breast development". 007 Breasts. http://www.007b.com/breast_development.php. Retrieved 2 May 2010.
  38. 38.0 38.1 J.M. Tanner; P.S. Davies (September 1985). "Clinical Longitudinal Standards for Weight and Height Velocity for North American Children". Journal of Pediatrics 107 (3): 317–329. http://www.ncbi.nlm.nih.gov/pubmed/3875704.
  39. 39.0 39.1 Byers, Frequently Asked Questions about Puberty, p. 28.
  40. Byers, Frequently Asked Questions about Puberty, p. 31.
  41. 41.0 41.1 Marshall, Human Growth, pp. 186–187.
  42. J.M. Tanner; P.S. Davies (September 1985). "Clinical Longitudinal Standards for Height and Height Velocity for North American Children". Journal of Pediatrics 107 (3): 317–329. http://www.ncbi.nlm.nih.gov/pubmed/3875704.
  43. 43.0 43.1 Byers, Frequently Asked Questions about Puberty, p. 32.
  44. D. Apter (1980). "Serum Steroids and Pituitary Hormones in Female Puberty: A Partly Longitudinal Study". Clinical Endocrinology (Oxford) 12 (2): 107–120. doi:10.1111/j.1365-2265.1980.tb02125.x .
  45. Neslihan Gungor; S.A. Arslanian (2002). "Nutritional Disorders: Integration of Energy Metabolism and its Disorders in Childhood". In M.A. Sperling (ed.). Pediatric Endocrinology (2nd ed.). Philadelphia, Pa.: Saunders. pp. 689–724 at 699–700. ISBN 9780721695396 .
  46. Byers, Frequently Asked Questions about Puberty, p. 29.
  47. Powell, Jillian Puberty Britannica Digital Learning page 7 https://books.google.com/books?id=KRKdAAAAQBAJ&pg=PA6&dq=puberty&hl=en&sa=X&ei=bBHgVObTOo-VyASql4HgBA&ved=0CF0Q6AEwCTgK#v=onepage&q=puberty&f=false

Sources[change | change source]

  • Byers, Ann (2007). Frequently asked questions about puberty. New York, N.Y.: Rosen Publishing. ISBN 978-1-4042-0966-4
  • Chen, Chuansheng; Farruggia, Susan (2002). "Culture and adolescent development [Unit 11, Chapter 2]". Online readings in psychology and culture. Ed. W.J. Lonner [et al.]. Bellingham, Wash.: Center for Cross-Cultural Research, Western Washington University. 
  • Marshall, William A.; J.M. Tanner (1986). Human growth: a comprehensive treatise (2nd ed.). New York, N.Y.: Plenum Press. ISBN 978-0-306-41952-2
  • Fass, Paula S. (2004). "Puberty". Encyclopedia of children and childhood: in history and society. Farmington Hills, Mich.: Thomson Gale. 

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