|
Chapter 8:
Adolescence: Physical Development
Puberty
Puberty
is the hormonal and physical changes that make a human
sexually mature.
Puberty was, and in
some cultures still is, celebrated by rites of passage or a coming of age ritual.
The declining age of
puberty is directly related to the increase in teenage pregnancy.
•
The
Secular Trend
Refers
to the decline at which we achieve puberty in developing
countries.
In 1830, the average
age of menarche in Northern Europe was over 17.
Today, the age has fallen
to under 13.
•
Puberty
if regulated by hormones:
Adrenal
Gland
Adrenal androgens: growth
of hair, skin changes, and sexual desire.
HPG
Axis
Hypothalamic hormone
causes the pituitary to secrete its hormones, which in turn, triggers the gonads to begin secreting their hormones.
Gonads
- Testes - Produces testosterone
Ovaries - Produces estrogen
Testosterone and estrogen occur in both sexes
•
Puberty
can begin for many reasons:
Genetics - Humans tend
to reach puberty at the age their parents did.
Weight - Children with
a high BMI (body mass index) tend to reach puberty at an earlier age.
Nutrition - High caloric
diets showed a correlation to reaching puberty at an earlier age.
Temperature - Warm temperatures
speed up the start of puberty.
Ossification
Bone density triggers
the hypothalamus.
Stress - Poverty and
difficult family situations can all factor in to early puberty.
Physical Changes
•
Primary
Sexual Characteristics
Physical
changes directly involved in reproduction
Menarche is the woman
first period
Spermarche is the manfirst
ejaculation
•
Secondary
Sexual Characteristics
Physical
changes not related to reproduction
Hair growth, voice changes,
acne
Breasts take an average
of 5 years to develop
•
Growth
Spurt = Dramatic increase in weight and height
At puberty, the hands,
feet, and legs grow first
Visual changes in boys
lag behind girls
Puberty Timetables: Individual Differences
•
Race
and ethnicity
African
Americans tend to begin earlier than other groups
This may be due to interactions
between biology and nutrition.
Asian
Americans tend to lag behind
•
Single
mother households
Studies found a correlation to early puberty and absent fathers
•
Socioeconomic
status
Low
SES in developing countries slows puberty
Low SES in developed countries speeds puberty
•
Breast
Development
Girls
responding to the “social norm” look upon breast
development favorably
When
bodies must be slender (ballerinas, gymnasts, etc.) it’s
looked upon negatively.
•
Menstruation
The
cultural reaction plays a role in the girl’s view
Navajo see it as a spiritual
growth
Mothers
have an important role in setting the attitude.
•
Spermarche
- Can be misunderstood and scary
Can
be concealed; private and embarrassing.
Timing of Puberty
•
They
tend to be shorter than late bloomers.
•
Early
development in boys tends to be ambiguous.
Since the penis, testicles,
and pubic hair are the first to develop in boys, others tend to not notice.
•
Early
blooming for girls can be a negative experience:
Noticed more often,
or attractive to, older boys...not always a good thing
Develop acting out and
externalizing problems
More likely to have
unprotected intercourse
More likely to become
depressed
More likely to not fit
into societies slim
model look
Changing schools at
this time can cause more trouble than usual.
.
Wrapping Up Puberty
•
Children’s
reactions to puberty depend on the environment in which they physically mature.
•
With
early maturing girls, the need to take special care to arrange the right body-environment fit is important.
•
Communication
about puberty can be vastly improved in most societies.
•
Parents
should sensitively discuss what is happening with the same sex child
•
K-8 schools and better sex education.
Body Image Issues
•
Susan
Hartman’s Five Dimensions: related to teenager’s overall self-esteem
Scholastic
Abilities
Conduct
Athletic
Skills
Peer
Likeability
Appearance
- Far outweighs any of the above
One out of two teenage
girls are trying to lose weight
•
Pressures
that make us self conscious about our weight:
Dating
Being
teased by family and friends
Media:
where both genders are vulnerable
Introducing Fiji to
western media, girls began having the same concerns about food and weight as girls in western nations.
Eating Disorders
•
Eating
Disorders are a pathological obsession with getting and staying thin.
They
appear in every SES level
They
are heritable with environmental influences
Can
be a symptom of a general tendency to be anxious and
depressed
At
the core of eating disorders is low self-efficacy
•
Anorexia
Nervosa
Refusing
to eat and having a distorted body image
Found
in about 1 in 1000 teenagers
Must
be at or below 85% body weight to be classified as having
anorexia
Severe
starvation can destroy vital organs
Experiencing Eating Disorders
•
Bulimia
Binging
(eating to excess) and purging (removing the food before
there is significant caloric intake)
Stomach
acid can produce major problems
Mouth sores, loss of
tooth enamel, ulcers, esophageal cancer
The
prevalence of bulimia is increasing
Self Image
•
Self-esteem
improves physical appeal
Your
personality can mold other’s concepts of you.
Accepting
objective images makes one vulnerable.
Those
who feel that their mirror image determines who they are
as a person, are more likely to be unhappy.
If
you believe it is your feelings that shape how you look, than you
are more likely to be happy.
Trends
•
A
person’s sexuality (within limits) is more acceptable today. However, it is more acceptable to wait until marriage.
•
Studies
of homosexuals show that:
Sexual
thoughts can occur as early as 10 years old
A
threshold of androgen is required for sexuality.
•
Environmental
feedback helps trigger our feelings.
Our
own changing bodies make us think and consider sex How
others react towards us triggers thoughts of
sex.
Sexual Intercourse
Average age at first encounter is late teens, but 1 in 4 teens began having
sex at age 15.
SES and culture contribute to age of first
encounter.
Predict
sexual activity:
TV watching behavior
Friends
Age of puberty
Culture
Other sexual activities
lead to intercourse
» Oral sex is more common among higher SES levels.
The
sexual double standard: boys can have sex, girls are
supposed to remain virgins.
•
ABC’s
of Sex Education
Abstain
If
not, Be Monogamous
Use
a Condom
•
U.S.
policy is to “Just Say No”
Doesn’t
always work
4 out of 10 teenage
girls get pregnant before 20
1 out of 4 teenage virgins have had oral sex
|
