Puberty begins the transformation from child to adult through hormonal and physical changes over 3 to 5 years. It starts with growth spurts and development of primary and secondary sex characteristics. While these changes are normal, some adolescents experience problems like early sexual activity, teenage pregnancy, STIs, sexual abuse, or drug use. Nutrition and stress can also impact pubertal development. The brain continues developing into the mid-20s, which may explain some risky behaviors due to an immature prefrontal cortex regulating impulses.

1. Kathleen Stassen Berger
Part V Chapter Fourteen
Adolescence: Biosocial Development
Puberty Begins
The Transformation of Puberty
Possible Problems
Prepared by Madeleine Lacefield 1
Tattoon, M.A.

2. Adolescence: Biosocial Development
…the body changes of early
adolescence rival those of infancy in
speed and drama…the difference
however is that adolescents are
aware…
2

3. Puberty Begins
• Puberty
– the time between the first onrush of
hormones and full adult physical
development… puberty usually last
three to five years… many more years
are required to achieve psychosocial
maturity
3

4. Puberty Begins
• Puberty
– menarche
• a girl’s first menstrual period, signaling that she
has begun ovulation. Pregnancy is biologically
possible, but ovulation and menstruation are
often irregular for years after menarche
– spermarche
• a boy’s first ejaculation of sperm. Erections can
occur as early as infancy, but ejaculation
signals sperm production. Spermache occurs
during sleep (in a ―wet dream‖) or via direct
stimulation
4

5. Puberty Begins
• Hormones
– organic chemical substances that are
produced by one body tissue and
conveyed via the bloodstream to
another to affect some physiological
function. Various hormones influence
thoughts, urges, emotions, and behavior
5

6. Puberty Begins
– pituitary
• a gland that, in response to a signal from the
hypothalamus, produces many hormones, including those
that regulate growth and control other glands, among
them the adrenal and sex glands
– adrenal glands
• two glands, located above the kidneys, that produce
hormones (including the ―stress hormones‖ epinephrine
[adrenaline] and norepinephrine)
– HPA axis (leads from brain to body to behavior)
• the hypothalamus-pituitary-adrenal axis, a route followed
by many kinds of hormones to trigger the changes of
puberty and to regulate stress, growth, sleep, appetite,
sexual excitement, and various other bodily changes
6

7. Puberty Begins
• Sex Hormones
– gonads
• paired sex glands (ovaries in females, testicles
in males) that produce hormones and gametes
– estradiol
• a sex hormone, considered the chief estrogen.
Females produce more estradiol than males do
– testosterone
• a sex hormone, the best known of the
androgens (male hormones); secreted in far
greater amounts by males then by females
7

8. Puberty Begins
• Sudden emotions
– behaviors that adolescents are best known
for are emotional and sexual
• testosterone at high or accelerating levels stimulates
rapid arousal of emotions, especially anger
• hormonal bursts lead to quick emotional extremes
(despair, ecstasy)
• for many boys, the increase in androgens causes
sexual thoughts and a desire to masturbate
• for many girls, the fluctuating estrogens increase
happiness in the middle of the menstrual cycle (at
ovulation) and sadness or anger at the end
8

9. Puberty Begins
• When will puberty Start?
– …the average age of onset varies…
• the average age is between 11 and 12
• but is still considered normal between
the ages of 8 and14
9

10. Puberty Begins
• Genes
– genes on the sex chromosomes
markedly affect the onset of puberty
– on average girls are about two years
ahead of boys in height
10

11. Puberty Begins
• Genes
– hormonally and sexually girls are ahead
by only a few months
– influence the timing of puberty in other
ways as well
11

12. Puberty Begins
• Body Fat
– genetic differences are apparent only
when every child is well fed
– stocky individuals begin puberty before
those with thinner builds
12

13. Puberty Begins
• Body Fat
– in both sexes chronic malnutrition
delays puberty
– secular trend
• a term that refers to the earlier and
greater growth of children due to
improved nutrition and medical care over
the last two centuries
13

14. Puberty Begins
• Stress
– the 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, or
when the neighbor is violent and impoverished
14

15. Puberty Begins
• Too Early, Too Late
– no one wants to be early or late, particularly
too early for girls and too late for boys
– early maturing girls have lower self-esteem,
more depression, poorer body image, and
boy-friends several years older
– often isolated from their on-time-maturing
peers, and tend to associate with older
adolescents
15

16. Puberty Begins
• Too Early, Too Late
– cohorts are crucial for boys
– early-maturing boys live in stressful urban
neighborhoods and are likely to befriend law-
breaking, somewhat older boys
– ethnic differences in age of puberty can add to
ethnic tensions in high school, especially for
boys
16

17. Nutrition
…the changes of puberty depend on
nutrition, yet many adolescents are
deficient in the necessary vitamins or
minerals
17

18. Nutrition
• Diet Deficiencies
– few than ½ of all teenagers consume
the recommended daily dose of iron
– more girls are anemic due to iron
depletion during menstruation
– ½ of adult bone mass is acquired from
age10-20, yet few adolescents consume
enough calcium
18

19. Nutrition
• Body Image
– a person’s idea of how his or her body
looks
– puberty alters the entire body making it
impossible for teenagers to welcome
every change
– girls diet to become thinner
– boys want to look taller and stronger
19

20. Nutrition
• Body Image
– stressed teenagers eat erratically or ingest
drugs hoping to lose weight
– Adolescents can give up, becoming lazy and
fat instead of strong and thin
– 12% of U.S. teenagers are overweight
– 2/3 (62%) of U.S. girls and almost 1/3 of the
boys are trying to lose weight according to
survey of 14,000 school students (MMWR
June 9,2006)
20

21. The Transformations of Puberty
• every body part changes during
puberty
• transformation from a child into an
adult is traditionally divided in two
parts: growth and sexuality
• the third division is the transformation
of the brain
21

22. The Transformations of Puberty
• Growing Bigger and Stronger
– growth spurt
• the relatively sudden and rapid physical
growth that occurs during puberty…
each body part increases size on a
schedule; weight usually precedes
height, and the limbs precede the torso
22

23. The Transformations of Puberty
• Growing Bigger and Stronger
– growth proceeds from the extremities to
the core
• fingers and toes lengthen before the
hands and feet
– the torso is the last body part to grow
• temporarily big-footed, long-legged, and
short-waisted
23

24. The Transformations of Puberty
24

25. The Transformations of Puberty
• Sequence: Weight, Height, Muscles
– bones lengthen and harden
– children eat more and gain weight
– when, where, and how much weight depends
on heredity, diet, exercise and gender
– girls gain much more fat than boys
– by age 17 the average girl has twice as mush
as her male classmate
25

26. The Transformations of Puberty
• Other body changes
– organs grow and become more efficient
– lungs triple in weight
– adolescents breathe more deeply and slowly
– the heart doubles in size and beats more
slowly
– blood pressure and volume both increase
– weight and height increase before the growth
of muscles and internal organs
26

27. The Transformations of Puberty
• Sexual
Maturation
– the second set
of changes
turns boys into
men and girls
into women
27

28. The Transformations of Puberty
• Sexual Body Changes
• primary sex characteristics
– the parts of the body that are directly involved
in reproduction, including the vagina, uterus,
ovaries, testicles, and penis
• secondary sex characteristics
– physical traits that are not directly involved in
reproduction but that indicate sexual maturity,
such as a man’s beard and a woman’s
breasts
28

29. The Transformations of Puberty
• Sexual Activity
– fantasizing, flirting, hand-holding, displaying,
and touching are all done in particular ways to
reflect gender, availability, and culture
– hormones trigger thoughts and emotions, but
the social context shapes through into
enjoyable fantasies, shameful preoccupations,
frightening impulses, or actual contact
29

30. The Transformations of Puberty
• Brain Development
– the limbic system—fear, emotional
impulse–matures before the prefrontal
cortex (planning ahead, emotional
regulation)
30

31. The Transformations of Puberty
• Caution Versus Thrills
– interdisciplinary research is needed to
integrate neurology and psychology
– caution is needed, lest ―incomplete brain
development [becomes] an explanation for just
about everything about teens that adults have
found perplexing, from sleep patterns to risk
taking and mood swings‖
31

32. The Transformations of Puberty
• Uneven Growth
– the immature prefrontal cortex may
allow ―troublesome adolescent behavior‖
– adolescents are capable of rational
thinking
– as in the rest of the teenager’s body,
brain growth is uneven
32

33. The Transformations of Puberty
• Neurological Advances
– with increased myelinaton, reactions become
lightening fast
– pruning occurs, and the dopamine system–
neurotransmitters that bring pleasure–is very
active
– before these advances are complete–about age
25–new connections between one synapse and
another ease acquisition of new ideas, words,
memories, values acquired during adolescence
are more likely to endure than those learned later,
after brain links are more firmly established
33

34. The Transformations of Puberty
• Body Rhythms
– brain rhythms affect body rhythms
– the brain of every living creature
responds to natural changes
– puberty alters biorhythms
– sleep patterns are irregular
34

35. Possible Problems
• growth and sexual awakening,
emotional intensity and hormonal
rushes, all can be quite wonderful
• maturation can cause problems
• 20% of young people have one
problem or several—while 80% are
not bedeviled by problems
35

36. Possible Problems
• Sex Too Soon
– adolescent sexuality can be problematic
• puberty occurs at young ages—early sexual
experiences correlate with depression and drug
use
• raising a child has become more complex,
which means that teenage pregnancy is no
longer welcomed or expected
• sexually transmitted infections are more
common and dangerous
36

37. Possible Problems
• Teenage Pregnancy
– ½ as common as it was 20 years ago in
the U.S.
– abortion rate had also decreased
– contraception use is higher and teen
intercourse is lower (MMWR, February
4th 2005)
37

38. Possible Problems
• Sexual Infections
– sexual transmitted infection (STI)
• a disease spread by sexual contact,
including syphilis, gonorrhea, genital
herpes, chlamydia, and HIV
38

39. Possible Problems
• Protection
– 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
39

40. Possible Problems
• Sexual Abuse
– child sexual abuse
• any erotic activity that arouses an adult
and excites, shames, or confuses a
child, whether or not the victim protests
and whether or not genital contact is
involved
40

41. Possible Problems
41

42. Possible Problems
• Drug Use and Abuse
– innocence is reflected in drug use
– few adolescents imagine becoming
addicted
– worldwide most young people use at
last one drug before age 18
42

43. Possible Problems
• Variations by Nation, Gender, and Ethnicity
– drug use varies from nation to nation
– laws and family practices are a part of the
reason for these variations
– gender differences are apparent for most
drugs, with boys having higher rates of
use than girls
43

44. Possible Problems
• 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
44

45. Possible Problems
• Learning from experience
– generational forgetting
• the idea that each new generation
forgets what the previous generation
learned about harmful drugs
45