Physical Development in Adolescence

1
Physical Development in Adolescence
2
CONCEPTIONS OF ADOLESCENCE

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

3
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.

4
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
  understood.

5
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
  absent.
• In societies where successful participation in
  economic life requires many years of education,
  adolescence is greatly expanded.

6
PUBERTY THE PHYSICAL TRANSITION TO ADULTHOOD

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

7
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
  characteristics.

8
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
  testes.

9
Changes in Body Size, Proportions, and MuscleFat
Makeup

• 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
  torso.
• 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.

10
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.

11
Sexual Maturation

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

12
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
  appears.
• Nature delays menstruation until the girls body
  is large enough for successful childbearing.

13
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.

14
Individual and Group Differences in Pubertal
Growth

• 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.

15
The Secular Trend

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

16
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.

17
THE PSYCHOLOGICAL IMPACT OF PUBERTAL EVENTS

• 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
  uninformed.

18
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.

19
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
  confusing.

20
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
  children.
• Compared to the moods of adults, adolescents
  feelings were less stable.
• Situational factors combine with hormonal
  influences to affect teenagers moodiness.

21
Pubertal Change, Emotion, and Social Behavior
cont.

• 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.

22
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
  attractive.
• 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.

23
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
  leadership.
• Late maturing girls were regarded as physically
  attractive, lively, sociable, and leaders at
  school.

24
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
  agemates.
• Early maturation is linked to a positive body
  image in males, whereas late maturation, to
  dissatisfaction with the physical self.

25
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
  consequences.
• 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
  adolescents.

26
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.

27
HEALTH ISSUES

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

28
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
  teenagers.

29
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.

30
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.

31
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.

32
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.

33
Sexual Activity cont.

• Adolescent Sexual Attitudes and Behavior
• Over the past thirty years, the sexual attitudes
  of both adolescents and adults have become more
  liberal.
• 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.

34
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.

35
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.

36
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.

37
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
  risk.

38
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
  countries.
• 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.

39
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
  Parenthood
• A high percentage of out-of-wedlock births are to
  members of low-income minorities, especially
  African-American, Native-American, and Hispanic
  teenagers.
• 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
  childbearing.

40
Pregnancy and Parenthood cont.

• Prevention Strategies
• Informing adolescents about sex and contraception
  beyond the facts of anatomy and reproduction is
  crucial.
• 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
  contraceptives.

• 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
  competence.
• Teenagers who look forward to a promising future
  are far less likely to engage in early and
  irresponsible sex.

41
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.

42
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.

43
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.

44
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
  behavior.
• 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.

45
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
  degree.
• 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.

46
Injuries

• 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.

47
MOTOR DEVELOPMENT, SPORTS PARTICIPATION, AND
PHYSICAL ACTIVITY

• 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
  steroids.

48

• 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
  week).
• Sports improve motor performance and provide
  lessons in competition, assertiveness, problem
  solving, and teamwork.

49

• 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.