1. Introduction
2. Fact or Fiction?
3. Puberty Begins
4. The Transformations of Puberty
5. Possible Problems
6. Closing Thoughts
2
Introduction
[Video: Physical Development
Introduction]
3
Physical Development
Fact or Fiction?
Fiction
Fact
1. Although the sequence of puberty
is variable, the age of onset is not.
2.The level of stress in a child’s family
can influence the onset of puberty.
3. Girls and boys who mature earlier or later than
their friends have a difficult time adjusting to puberty.
4. By the end of adolescence, cognitive ability
is equal to that of a fully mature adult.
4
Hormones
What is the biological sequence of puberty?
Growth
hormone (GH)
Hormones
Hypothalamus
Pituitary
Gonadotropin
- releasing
hormone
Adrenal
glands
Gonads
(ovaries or
testicles)
Increase in
many
hormones,
including
testosterone
and estrogen
Growth spurt
Primary sex
characteristics
Secondary sex
characteristics
HPA axis and HPG axis
hormone: An organic chemical substance;
produced by one body tissue and conveyed
via the bloodstream to another to affect
some physiological function.
5
When Will Puberty Start?
What is the relationship between age and puberty?
Age and
Puberty
Genes and Gender
2/3 of variation in age of
puberty is genetic, evident in
families and ethnic groups
Body Fat
Most girls reach at least
100 pounds (45 kilograms)
before they can experience
their first period
(Ge et al., 2007; Susman et al., 2010;
van den Berg & Boomsma, 2007)
(Berkey et al., 2000)
Stress
Although the link between stress and
puberty is known, not every scientist
agrees that stress causes early puberty
(Ellis, 2004)
secular trend: long-term upward or downward
direction of a certain set of statistical measurements.
6
Too Early, Too Late
What are some effects of early- or late-arriving puberty?
Early-maturing girls
Early- and late-maturing boys
Tend to have lower self-esteem, more depression,
and poorer body image than do other girls
(Compian et al., 2009).
Today, early maturing boys are more aggressive,
law-breaking, and alcohol abusing than later-maturing
boys (Biehl et al., 2007; Lynne et al, 2007).
Less exercise contributes to their difficulties
(Davison et al., 2007).
According to research from Finland, slow-developing
boys tend to be more anxious, depressed, and afraid
of sex (Lindfors et al., 2007).
Those with older boyfriends are at increased risk
for using drugs and alcohol (Wiechold et al., 2003).
May face relational bullying and physical violence
(Shreck et al., 2007).
7
Eating Habits and Body Image
What are symptoms of the eating disorders anorexia and bulimia nervosa?
Anorexia
Refusal to maintain a
weight that is at least
85 percent of BMI.
Intense fear of
weight gain.
Disturbed body
perception and denial
of the problem.
Bulimia
Bingeing and purging
at least once a week
for three months.
Uncontrollable urges
to overeat.
A distorted
perception
of body size.
Absence of
menstruation (in
adolescent and adult
females).
10
Growing Bigger and Stronger
What are some differences in growth between boys and girls?
Running Speed of Girls and Boys, Age 6 to 18
Throwing Performance of Boys and Girls, Age 6 to 18
Ball throw for distance
30-yard (27.4-m) dash
60
3
50
4
Meters
Running
time
(seconds)
40
30
5
20
6
10
0
7
6
8
10
12
14
Age (years)
16
18
6
Boys
8
10
12
14
16
18
Age (years)
Girls
Source: Malina et al., 2004, p. 221.
Source: Malina et al., 2004, p. 222.
13
Sexual Maturation
By percent, how many adolescents are sexually active and use condoms?
Condom Use Among 15-Year-Olds (Tenth Grade)
Country
Sexually Active
(% of total)
Used Condom at Last Intercourse
(% of those sexually active)
France
20
84
Israel
14
72
Canada
23
78
United States
41
68
England
29
83
Russia
33
75
Sources: Nic Gabhainn et al., 2009; MMWR, June 4, 2010
14
Brain Development
Are teenage brains like those of children or adults?
Gray Matter
HA B
I
J
K
N
Q
5
C
M
L
P
O
E
F
D
G
1.0
0.9
0.8
0.7
Age
20
0.6
0.5
0.4
0.3
0.2
0.1
0.0
The scale
represents the
proportion of
gray matter
15
Brain Development
[Video: Brain Growth, Infancy Until Age 18]
16
Sex Too Soon
What are some hazards that teenage mothers face?
1. What does early
Factsex
orcorrelate
Fiction?with?
Depression andFiction
drug use.
Fact
2. Compared with 100 years ago, how
many teenage mothers are unwed?
85 percent today, compared with 100 years
ago when most teenage mothers were wed.
3. What is the expense
of raising a child today?
Raising a child is more complex and
expensive than in the past.
4. What about receiving help from
the mothers of teenage mothers?
Mothers of teenagers are usually employed
and less available to help with their young
daughters and new grandchildren.
5. What other complication
can teenage mothers face?
These days, sexually transmitted infections
are more common and dangerous.
17
Drug Use and Abuse
How many and what kind of drugs do high school students use?
Drug Use by U.S. High School Seniors in the Past 30 Days
Percent
60
reporting
use of drug
50
40
30
20
10
0
1976
‘78
‘80
‘82
‘84
‘86
‘88
‘90
‘92
‘94
‘96
‘98
2000
‘02
‘04
‘06
‘08
Year
Cocaine
Amphetamines
Other illicit drugs
(not marijuana)
Marijuana
Cigarettes
Alcohol
Source: Johnston et al., 2008.
21
Learning from Experience
What are some learning benefits that occur due to physical growth during adolescence?
Reactions become lightning fast with
increased myelination and slower inhibition
More active reward center in
brain and production of positive
neurotransmitters
Benefits of Adolescence
Synaptic brain growth occurs
before another wave of pruning
Prefrontal cortex of brain
still developing
22
Closing Thoughts
How does the behavior of
adolescents change as a result
of some of the physical changes
they experience during this
phase of life?
23