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Physical Development in Adolescence


Following menarche, pubic hair and breast development are ... Pubic hair emerges a short time later, about the same time the penis begins to enlarge in size. ... – PowerPoint PPT presentation

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Title: Physical Development in Adolescence

Physical Development in Adolescence
  • The beginning of adolescence is marked by
    puberty, the biological changes that lead to an
    adult-sized body and sexual maturity.

The Biological Perspective
  • Rousseau and Hall viewed adolescence as a time of
    great upheaval and turbulence.
  • Freud called adolescence the genital stage, a
    period in which instinctual drives reawaken and
    shift to the genital region. Psychological
    conflict and volatile, unpredictable behavior
    mark this stage.

The Environmental Perspective
  • The overall rate of severe psychological
    disturbance rises only slightly from childhood to
    adolescence, when it is the same as in the adult
    populationabout 20 percent.
  • Margaret Mead promoted the idea that the social
    environment is entirely responsible for the
    negative and positive experiences of teenagers.
  • Meads work convinced researchers that greater
    attention must be paid to social and cultural
    influences for adolescent development to be

A Balanced Point of View
  • Adolescence in modern industrialized nations is
    commonly divided into three phases
  • Early adolescence, from 11 or 12 to 14 years of
    age, a period of rapid pubertal change.
  • Middle adolescence, from 14 to 18 years, when
    pubertal changes are nearly complete.
  • Late adolescence, from 18 to 21 years, when the
    young person achieves full adult appearance and
    faces more complete assumption of adult roles.
  • Adolescence is neither biologically nor socially
    determined, but rather a product of the two.
  • Although simpler societies have a shorter
    transition to adulthood, adolescence is not
  • In societies where successful participation in
    economic life requires many years of education,
    adolescence is greatly expanded.

  • Girls reach puberty, on the average, 2 years
    earlier than do boys.

Hormonal Changes
  • The pituitary gland, located at the base of the
    brain, plays a vital role in physical growth.
    Growth hormone (GH) and thyroxine contribute to
    the gains in body size and completion of skeletal
    maturation during puberty.
  • Estrogens are typically thought of as female
    hormones and androgens as male hormones however,
    both types are present in each sex, but in
    different amounts.
  • The boys testes release large quantities of the
    androgen testosterone, which leads to muscle
    growth, body and facial hair, and other sex

Hormonal Changes cont.
  • Estrogens cause the girls breasts, uterus, and
    vagina to mature, the body to take on feminine
    proportions, fat to accumulate, and regulation of
    the menstrual cycle.
  • Adrenal androgens influence the girls height
    spurt and stimulate growth of underarm and pubic
    hair. Boys physical characteristics are mainly
    influenced by androgen secretions from the

Changes in Body Size, Proportions, and MuscleFat
  • The growth spurt is the rapid gain in height and
    weight that is the first outward sign of puberty.
  • Growth in body size is complete for most girls by
    age 16 and for boys by age 17 1/2.
  • During puberty, the cephalocaudal trend of
    infancy and childhood reverses. At first, the
    hands, legs, and feet accelerate, and then the
  • The most obvious difference in boys and girls
    body proportions is the broadening of the
    shoulders relative to the hips in boys and the
    broadening of the hips relative to the shoulders
    and waist in girls.

Changes in Body Size, Proportions, and MuscleFat
Makeup cont.
  • Around age 8, girls start to add more fat than do
    boys on their arms, legs, and trunk. In contrast,
    the arm and leg fat of adolescent boys decreases.
  • Boys develop larger skeletal muscles, hearts, and
    lung capacity.
  • Boys greater gain in muscle strength contributes
    to their superior athletic performance during the
    adolescent years.

Sexual Maturation
  • Primary sexual characteristics are physical
    features that involve the reproductive organs
  • Secondary sexual characteristics are features
    that are visible on the outside of the body and
    serve as additional signs of sexual maturity.

Sexual Maturation cont.
  • Sexual Maturation in Girls
  • Female puberty usually begins with the budding of
    the breasts and the growth spurt.
  • Menarche is a girls first menstruation. It
    typically happens around 12 1/2 years for North
    American girls, but the age range is wide.
  • Following menarche, pubic hair and breast
    development are completed and underarm hair
  • Nature delays menstruation until the girls body
    is large enough for successful childbearing.

Sexual Maturation cont.
  • Sexual Maturation in Boys
  • The first sign of puberty in boys is the
    enlargement of the testes, accompanied by changes
    in the scrotum.
  • Pubic hair emerges a short time later, about the
    same time the penis begins to enlarge in size.
  • The growth spurt occurs much later in the
    sequence of pubertal events for boys than for
    girls. Also, boys height gain is more intense
    and longer lasting.
  • After the peak in body growth, facial and body
    hair emerges. The voice deepens at the peak of
    the growth spurt.
  • Spermarche is the first ejaculation of seminal
    fluid. It occurs around age 13.

Individual and Group Differences in Pubertal
  • Physical health is largely responsible for
    variations. In poverty-stricken regions where
    malnutrition and infectious disease are
    widespread, menarche is greatly delayed.
  • Several studies indicate that girls exposed to
    early family conflict tend to reach menarche
    early, whereas those with highly affectionate
    family ties reach menarche relatively late.
  • Identical twins generally reach menarche within a
    month or two of each other, whereas fraternal
    twins differ by about 12 months.
  • A sharp rise in body weight and fat may trigger
    sexual maturation in females.
  • Variations in pubertal growth also exist between
    regions of the world and SES groups. Heredity
    seems to play little role.

The Secular Trend
  • The secular trend, or generational change,
    describes how children in industrialized nations
    are growing faster and larger than in generations
  • Secular gains in height has slowed, but
    overweight and obesity rates have soared,
    contributing to the trend toward earlier

Changing States of Arousal
  • On average, sleep declines from 10 hours in
    middle childhood to 7 1/2 to 8 hours in
    adolescence. Yet, teenagers need nearly as much
    sleep as they did during the school years.
  • The tendency to stay up late strengthens with
    pubertal maturation.
  • Sleep-deprived adolescents tend to achieve less
    well in school, suffer more often from depressed
    moods and report irregular sleep schedules, which
    add to daytime sleepiness and behavior problems.

  • Reactions to Pubertal Changes
  • Girls Reactions to Menarche
  • Research of a generation or two ago indicated
    that menarche was often traumatic.
  • Today, girls often report a mixture of positive
    and negative emotions. Their feelings toward
    menarche depend on prior knowledge and support
    from family members.
  • For girls who have no advance information,
    menarche can be shocking and disturbing. Today,
    however, no more than 10 to 15 percent are

Reactions to Pubertal Changes cont.
  • Boys Reactions to Spermarche
  • Boys respond to spermarche with mixed feelings.
  • Virtually all boys know about ejaculation ahead
    of time, but few get any information from
    parents most obtain it from reading material.
  • Overall, boys seem to get much less social
    support for the physical changes of puberty than
    do girls.

Reactions to Pubertal Changes cont.
  • Cultural Influences
  • Many tribal and village societies celebrate
    puberty with a rite of passagea community-wide
    event that marks an important change in privilege
    and responsibility.
  • Western culture grants little formal recognition
    to movement from childhood to adolescence or from
    adolescence to adulthood.
  • Modern adolescents are confronted with many ages
    at which they are granted partial adult status
    (for example, an age for starting employment, for
    driving, for voting, and for drinking). This can
    make the process of becoming an adult especially

Pubertal Change, Emotion, and Social Behavior
  • Adolescent Moodiness
  • Although higher pubertal hormone levels are
    related to greater moodiness, these relationships
    are not strong.
  • In several studies, the mood fluctuations of
    children, adolescents, and adults were tracked by
    having them carry electronic pagers.
  • Negative events increased steadily from childhood
    to adolescence, and teenagers also seemed to
    react to them with greater emotion than did
  • Compared to the moods of adults, adolescents
    feelings were less stable.
  • Situational factors combine with hormonal
    influences to affect teenagers moodiness.

Pubertal Change, Emotion, and Social Behavior
  • ParentChild Relationships
  • Although rate of conflict declines with age as
    parents and adolescents spend less time together,
    its emotional intensity rises into
    mid-adolescence. Both parents and teenagers
    report feeling less close to one another during
    this time.
  • In late adolescence, heated arguments decline.
  • A modern substitute for physical departure from
    the family seems to be the psychological
    distancing between parents and children.
  • The greater the gap between parents and
    adolescents views of the teenagers readiness to
    take on developmental tasks, the more quarreling
    there tends to be.
  • Only a small minority of families experience a
    serious break in parentchild relationships.

Early versus Late Maturation
  • Effects of Maturational Timing
  • Early maturing boys appear advantaged in many
    aspects of emotional and social functioning.
  • Both adults and peers viewed them as relaxed,
    independent, self-confident, and physically
  • They held many leadership positions in school and
    tended to be athletic stars.
  • Late maturing boys were viewed as anxious, overly
    talkative, and attention seeking in behavior.

Early versus Late Maturation cont.
  • Effects of Maturational Timing cont.
  • Early maturing girls had emotional and social
    difficulties. They were below average in
    popularity, appeared withdrawn and lacking in
    self-confidence, and held few positions of
  • Late maturing girls were regarded as physically
    attractive, lively, sociable, and leaders at

Early versus Late Maturation cont.
  • The Role of Physical Attractiveness
  • Societys view of an attractive female is
    consistent with the girlish shape that favors the
    late developer.
  • The male image is tall, broad-shouldered, and
    muscular consistent with the development of the
    early maturing boy.
  • Body image is the conception of and attitude
    toward ones physical appearance.
  • Early maturing girls have a less positive body
    image than do their on-time and late maturing
  • Early maturation is linked to a positive body
    image in males, whereas late maturation, to
    dissatisfaction with the physical self.

Early versus Late Maturation cont.
  • The Importance of Fitting In with Peers
  • Early maturing girls and late maturing boys have
    difficulty because they fall at the extremes of
    physical development.
  • Adolescents feel most comfortable with peers who
    match their own level of biological maturity.
  • Early maturing adolescents of both sexes seek out
    older companionssometimes with unfavorable
  • In one study, early maturing sixth-grade girls
    felt better about themselves when they attended
    kindergarten through sixth grade (K-6) rather
    than kindergarten through eighth grade (K-8)
    schools, where they could mix with older

Early versus Late Maturation cont.
  • Long-Term Consequences
  • Many early maturing boys and late maturing girls
    became rigid, conforming and somewhat
    discontented adults.
  • Late maturing boys and early maturing girls often
    developed into adults who were independent,
    flexible, cognitively competent, and satisfied
    with the direction of their lives.
  • These long-term outcomes may not hold in all
    cultures. In a Swedish study, achievement
    difficulties of early maturing girls persisted
    into young adulthood.
  • The effects of maturational timing involve a
    complex blend of biological, immediate social
    setting, and cultural factors.

  • As adolescents are granted greater autonomy,
    personal decision making becomes important, in
    health as well as other areas.

Nutritional Needs
  • During the growth spurt, boys require about 2,700
    calories a day and much more protein. Girls
    require about 2,200 calories and somewhat less
    protein than boys.
  • This increase in nutritional requirements comes
    at a time when the eating habits of many young
    people are the poorest.
  • The most common nutritional problem of
    adolescence is iron deficiency.
  • Most adolescents do not get enough calcium,
    riboflavin, and magnesium in their diets.
  • Most fad diets are too limited in nutrients and
    calories to be healthy for fast-growing, active

Serious Eating Disturbances
  • Girls who reach puberty early, who are very
    dissatisfied with their body images, and who grow
    up in homes where concern with weight and
    thinness is especially strong are at risk for
    developing eating problems.

Serious Eating Disturbances cont.
  • Anorexia Nervosa
  • Anorexia nervosa is an eating disorder in which
    individuals starve themselves because of a
    compulsive fear of getting fat.
  • Anorexics have an extremely distorted body image.
    Even after they become severely underweight, they
    conclude that they are fat.
  • Anorexics lose between 25 and 50 percent of their
    body weight and appear painfully thin, and as
    many as 10 percent die of the disorder.
  • Physical symptoms include cessation of
    menstruation or non-occurrence of menarche, pale
    skin, brittle discolored nails, fine dark hairs
    appearing all over the body, and extreme
    sensitivity to cold.
  • Often parents of anorexics have high expectations
    for achievement and social acceptance and are
    overprotective and controlling.
  • Anorexia nervosa tends to run in families,
    suggesting a genetic influence.
  • Treatment usually involves a combination of
    hospitalization, family therapy, and sometimes,
    applied behavior analysis. Still, only 50 percent
    of anorexics fully recover.

Serious Eating Disturbances cont.
  • Bulimia Nervosa
  • Bulimia nervosa is an eating disorder in which
    individuals go on eating binges followed by
    deliberate vomiting and other purging techniques
    such as heavy doses of laxatives.
  • The repeated vomiting causes erosion of tooth
    enamel, and can cause life-threatening damage to
    the throat and stomach.
  • Bulimia is much more common than anorexia
    nervosa. About 1 to 3 percent of teenage girls
    are affected only 5 percent of bulimic girls
    have previously been anorexic.
  • Typically, bulimics are not just impulsive
    eaters they also lack self-control in other
    areas of their lives.
  • Bulimics are aware of their abnormal eating
    habits and feel depressed and guilty about them.
    As a result, bulimia is usually easier to treat
    than anorexia.

Sexual Activity
  • The Impact of Culture
  • Typically, American parents give children little
    information about sex, discourage them from
    engaging in sex play, and rarely talk about sex
    in their presence.
  • When young people become interested in sex, they
    seek information elsewhere, turning to friends,
    books, magazines, movies, and television.
  • Adolescents receive contradictory and confusing
    messages about sex. Adults emphasize that sex at
    a young age and outside of marriage is wrong, yet
    the broader social environment extols the
    excitement and romanticism of sex.

Sexual Activity cont.
  • Adolescent Sexual Attitudes and Behavior
  • Over the past thirty years, the sexual attitudes
    of both adolescents and adults have become more
  • The rate of premarital sex among young people
    rose over several decades, but recently declined
    slightly, largely due to the risk of sexually
    transmitted disease.
  • Males tend to have their first intercourse
    earlier than females, and sexual activity is
    especially high among African-American
    adolescents (particularly boys).
  • Most teenagers engage in relatively low levels of
    sexual activity.

Sexual Activity cont.
  • Characteristics of Sexually Active Adolescents
  • Teenage sexual activity is linked to a range of
    variables including early physical maturation,
    parental divorce, single-parent and stepfamily
    homes, large family size, weak parental
    monitoring, disrupted parentchild communication,
    sexually active friends and older siblings, poor
    school performance, lower educational
    aspirations, and a tendency to engage in
    norm-violating acts.
  • Early sexual activity is more common among young
    people from economically disadvantaged homes.

Sexual Activity cont.
  • Contraceptive Use
  • One-third to one-half of sexually active American
    teenagers do not use contraception at all or use
    it only occasionally.
  • They do not do the kind of planning and decision
    making necessary to protect themselves from
    harmful outcomes.
  • Adolescents lack of planning before sex may be
    attributed to concerns about others opinions of
    them. Intense self-reflection leads many
    adolescents to believe that they are unique and
    invulnerable to danger.
  • Teenagers who talk openly with their parents
    about sex are more likely to use birth control.
  • Many teens are uncomfortable about asking parents
    questions about sex or contraception. In
    addition, many do not know where to get birth
    control counseling and devices.

Sexual Activity cont.
  • Sexual Orientation
  • About 3 to 6 percent of young people discover
    they are lesbian or gay.
  • Recent evidence indicates that heredity makes an
    important contribution to homosexuality.
    According to some researchers, certain genes
    affect the level or impact of prenatal sex
    hormones, which modify brain structures in ways
    that induce homosexual feelings and behavior.
  • Family factors, such as parental coldness and
    distance, are also associated with homosexuality.
  • Homosexuality probably results from a variety of
    biological and environmental combinations that
    are not well understood.

Sexually Transmitted Disease
  • Adolescents have the highest rates of sexually
    transmitted disease (STD) of any age group. One
    out of six sexually active teenagers contract an
    STD each year.
  • Teenagers in greatest danger of STD are
    poverty-stricken young people who feel a sense of
    inferiority and hopelessness about their lives.
  • The most serious STD is AIDS. Drug-abusing and
    homosexual adolescents account for most cases,
    but heterosexual spread has increased, especially
    among females.
  • As a result of school courses and media
    campaigns, over 90 percent of high school
    students are aware of the basic facts about AIDS,
    but some hold false beliefs that put them at

Pregnancy and Parenthood
  • Each year, approximately 900,000 American
    teenagers become pregnant, 30,000 under the age
    of 15. Despite a steady decline since 1991, the
    adolescent pregnancy rate in the United States is
    higher than that of most other industrialized
  • The United States differs from other
    industrialized nations in that
  • Effective sex education reaches fewer teenagers.
  • Convenient, low-cost contraceptive services for
    adolescents are scarce.
  • Many more families live in poverty, which
    encourages young people to take risks without
    considering the consequences of their behavior.

Pregnancy and Parenthood cont.
  • Many teenage mothers are on welfare. Their
    employment opportunities are usually restricted
    to unsatisfying, low-paid jobs. Adolescent
    fathers obtain less education and are also
    economically disadvantaged.
  • Babies of adolescent mothers often experience
    prenatal and birth complications, especially low
    birth weight.
  • Compared to adult mothers, adolescent mothers
    know less about child development, have
    unrealistically high expectations, perceive their
    infants as more difficult, and interact less
    effectively with their infants.
  • If the teen mother finishes high school, avoids
    additional births, and finds a stable marriage
    partner, long-term disruptions are less severe.
  • Correlates and Consequences of Adolescent
  • A high percentage of out-of-wedlock births are to
    members of low-income minorities, especially
    African-American, Native-American, and Hispanic
  • Only 50 percent of adolescent mothers finish high
    school, compared to 96 percent of those who wait
    to become parents.
  • Teenage motherhood reduces the chances of
    marriage. When these mothers do marry, they are
    more likely to divorce than their peers who delay

Pregnancy and Parenthood cont.
  • Prevention Strategies
  • Informing adolescents about sex and contraception
    beyond the facts of anatomy and reproduction is
  • A new wave of sex education programs teaches
    adolescents the skills they need to resist
    pressures to engage in early and unprotected sex,
    promotes the value of abstinence, and provides
    information about and ready access to
  • Some argue that the key to pregnancy prevention
    is through providing teenagers with easy access
    to contraceptives. Others feel this is
    equivalent to saying that early sex is OK.
  • Efforts to prevent adolescent pregnancy and
    parenthood must go beyond improving sex education
    and access to contraception to build social
  • Teenagers who look forward to a promising future
    are far less likely to engage in early and
    irresponsible sex.

Pregnancy and Parenthood cont.
  • Intervening with Adolescent Parents
  • Young single mothers need health care for
    themselves and their children, encouragement to
    stay in school, job training, instruction in
    parenting and life management techniques, and
    high quality, affordable child care.
  • Adolescent mothers also benefit from family
    relationships that are sensitive to their
    developmental needs.
  • Programs focusing on fathers are attempting to
    increase their emotional and financial commitment
    to the baby.

Substance Use and Abuse
  • By age 14, 56 percent of American young people
    have already tried smoking, 70 percent drinking,
    and 32 percent at least one illegal drug.
  • These high figures represent a decade of decline
    in alcohol and drug use, followed by a steady
    increase during the past few years and than a
    slight drop.
  • The majority of substance experimenters are
    psychologically healthy, sociable, and curious
    young people.

Substance Use and Abuse cont.
  • However, a worrisome minority of high-risk
    teenagers move from substance use to abusefirst
    experimenting, then taking drugs regularly,
    requiring increasing amounts to achieve the same
    effect, and finding themselves unable to stop,
    and using enough to impair their ability to meet
    school, work, and other responsibilities.
  • Although cigarette smoking has received the least
    attention, in the long run, it may be the
    deadliest substance.

Substance Use and Abuse cont.
  • Correlates and Consequences of Adolescent
    Substance Abuse
  • In contrast to experimenters, drug abusers are
    seriously troubled adolescents who are inclined
    to express their unhappiness through antisocial
  • Peer encouragement is a strong predictor of
    substance abuse.
  • Other contributing factors include a low-SES
    background, family mental health problems,
    parental and older sibling drug use, and lack of
    parental involvement, physical and sexual abuse,
    and poor school performance.
  • Adolescent drug addiction is associated with
    depression and antisocial behavior, as well as
    high rates of divorce and job loss.

Substance Use and Abuse cont.
  • Prevention and Treatment
  • School-based programs that promote effective
    parenting and teach students how to resist peer
    pressure help reduce experimentation to some
  • Since some drug-taking seems inevitable,
    interventions that prevent adolescents from
    endangering themselves and others when they do
    experiment are essential.
  • Not much is known about the best way to treat
    adolescent drug abuse. Even the most
    comprehensive programs have high relapse rates.

  • Motor vehicle collisions are the leading killer
    of adolescents, accounting for 42 percent of
    deaths between the ages of 15 and 19.
  • The majority of other unintentional injuries are
    caused by firearms.
  • A third form of adolescent injuryless prevalent
    but still serious and largely avoidableis sports
    related. Each year, about one-third of students
    involved in sports experience injuries that
    require medical treatment.
  • Unrealistic demands by coaches are an important
    source of athletic injuries.

  • Girls gains in motor performance are slow and
    gradual, leveling off by age 14.
  • Boys show a dramatic spurt in strength, speed,
    and endurance that continues through the end of
    the teenage years.
  • Some adolescents become so obsessed with
    physical prowess that they try to increase their
    skill artificially through the use of anabolic

  • High school girls sports participation
    quadrupled during the decade after a legal
    mandate required schools to provide equal
    opportunities for girls in 1972. Participation
    has continued to increase, although it still
    falls far short of boys.
  • Overall, 72 percent of high school boys but only
    57 percent of girls report regular vigorous
    physical activity (at least 20 minutes 3 days a
  • Sports improve motor performance and provide
    lessons in competition, assertiveness, problem
    solving, and teamwork.

  • Only 56 percent of American high school students
    are enrolled in physical education, and only 29
    percent attend class daily. Attendance drops off
    with each grade, especially for girls.
  • Required daily physical education, aimed at
    helping teenagers find pleasure in sports and
    exercise, is a vital means of promoting
    adolescent health.