Kathleen Stassen Berger
Part V
Chapter Fourteen
Adolescence: Biosocial Development
Puberty Begins
Nutrition
The Transformation of Puberty
Health Hazards
1
Puberty Begins
• Puberty
– time between the first
onrush of hormones
and full adult physical
development
– lasts three to five
years
– many more years
required to achieve
psychosocial maturity
2
• menarche: girl’s first menstrual period
– signals that she has begun ovulation
– pregnancy biologically possible, but ovulation
and menstruation often irregular
• spermarche: boy’s first ejaculation of
sperm
– Erections occur early as infancy.
– Ejaculation signals sperm production.
– Spermache occurs during sleep or via direct
stimulation.
3
• hormones: Organic chemical substances
produced by one body tissue and conveyed
via the bloodstream to another.
– affect some physiological function
– influence:
•
•
•
•
thoughts
urges
emotions
behavior
4
• pituitary gland: produces hormones that:
– regulate growth
– control adrenal and sex glands
• adrenal glands: produce hormones
epinephrine [adrenaline] and
norepinephrine
5
Sex Hormones
• gonad
– Paired sex glands that produce hormones and
gametes.
• estradiol
– sex hormone considered chief estrogen
– females produce more estradiol than males
• testosterone
– sex hormone, the best known of the
androgens
– greater amounts secreted by males than
females
6
Age and Puberty
• When will puberty
start?
– average age is
between 11 and 12
• considered normal
between the ages
of 8 and14
7
• Genes
– Genes on the sex chromosomes markedly
affect the onset of puberty.
– On average girls are about two years ahead of
boys in height.
• Body Fat
– Genetic differences are apparent only when
every child is well fed.
– Stocky individuals begin puberty before those
with thinner builds.
8
Stress
• Production of many hormones is directly
connected to stressful experience via the
HPA axis.
– Affects pubertal hormones by increasing them.
– Puberty tends to arrive earlier if:
• a child’s parents are sick, addicted or divorced.
• neighborhood is violent and impoverished.
9
Too Early, Too Late
• Early-maturing girls:
– have lower selfesteem
– more depression
– poorer body image
– boyfriends several
years older
10
• Early-maturing boys:
– more aggressive, lawbreaking, and alcohol
abusing
– Ethnic differences in age
of puberty can add to
tensions in high school,
especially for boys.
11
Nutrition
• The changes of puberty depend on nutrition.
– Many adolescents deficient in vitamins
• Fewer than ½ of teenagers consume
recommended daily dose of iron.
• More girls anemiciron
– ½ of adult bone mass acquired from age1020
• few adolescents consume enough calcium
12
Body Image
– A person’s idea of how his
or her body looks.
– Girls:
• diet to become thinner.
– Boys:
• want to look taller and
stronger.
13
• Origins of Disordered Eating
– eventual outcome of odd eating
habits
• go without food for 24 hours
• try new diets
• take diet drugs
– Serves psychological or social
need rather than any biological
necessity.
14
The Transformations of Puberty
• growth spurt: sudden, rapid physical growth
during puberty
– Each body part increases size on a schedule.
• weight precedes height
• limbs precede the torso
– Growth proceeds from the extremities to the
core.
• fingers and toes lengthen before the hands and
feet
15
16
Sexual Maturation
• Sexual Body Changes
– primary sex characteristics
– vagina
– uterus
– ovaries
– testicles
– penis
17
• Secondary sex characteristics
– Physical traits that are not directly
involved in reproduction
• man’s beard
• woman’s breasts
18
Sexual Activity
• fantasizing, flirting, hand-holding, displaying,
and touching
• reflect gender, availability, and culture
• Social context shapes:
– enjoyable fantasies
– shameful preoccupations
– frightening impulses
– actual contact
19
Sex Too Soon
• Adolescent sexuality can be problematic.
– puberty occurs at young ages
– raising a child has become more complex
– teenage pregnancy no longer welcomed or
expected
– sexually transmitted infections more
common and dangerous
– sexual abuse more common
20
Teenage Pregnancy
• ½ as common as it was 20 years ago in
the U.S
• abortion lower.
• contraception use higher
• teen intercourse is lower
21
Sexual Infections
• Sexual transmitted
infection (STI)
– disease spread by
sexual contact
including:
•
•
•
•
•
syphilis
gonorrhea
genital herpes
chlamydia
HIV.
22
– Regular medical care can
prevent and treat STIs.
– Almost every teenager knows
that pregnancy and STIs can
be prevented.
– Teenagers tend to confuse
appearance and reality
• well-dressed partners could
have STIs.
23
Sexual Abuse
• child sexual abuse: Any erotic activity
that arouses an adult and excites, shames,
or confuses a child.
– whether or not victim protests
– whether or not genital contact is involved.
24
25
Drug Use and Abuse
• innocence reflected in
drug use
• Worldwide most young
people use at last one
drug before age 18.
26
Drug Use and Abuse
• Variations by Nation, Gender, and Ethnicity
– Laws and family practices
– Gender differences
• boys having higher rates of use than girls.
27
• Harm from Drugs
– Adolescents think adults exaggerate the
harm of teen drug use.
– Drugs interfere with healthy eating and
digestion.
– Drugs appear to make problems better,
which leads to abuse and addition.
28
29
Learning from experience—or Not
• Generational forgetting
– The idea that each new
generation forgets what
the previous generation
learned about harmful
drugs.
30