CHAPTER 11 - OUTLINE
PHYSICAL DEVELOPMENT
I. CONCEPTIONS OF ADOLESCENCE (pp. 350-351)
A. The beginning of adolescence is marked by puberty, the biological changes
that lead to an adultsized body and sexual maturity.
B. In societies where successful participation in economic life requires many years
of education, adolescence is greatly extended.
II. PUBERTY: THE PHYSICAL TRANSITION TO ADULTHOOD (pp. 351-355)
A. Pubertal growth is regulated by genetically influenced hormonal processes.
Girls reach puberty, on the average, 2 years earlier than boys.
B. Hormonal Changes (pp. 351-352)
1. Growth hormone (GH) and thyroxine contribute to the gains in body size and
completion of skeletal maturation during puberty.
2. Estrogens are typically thought of as female hormones and androgens as
male hormones; however, both types are present in each sex.
3. The boy's testes release large quantities of the androgen testosterone,
which leads to muscle growth, body and facial hair, and other sex
characteristics.
4. Estrogens cause the girl's breasts, uterus, and vagina to mature, the body
to take on feminine proportions, fat to accumulate, and the menstrual cycle to
begin.
C. Body Growth (pp. 352-353)
1. The growth spurt is the rapid gain in height and weight that is the first
outward sign of puberty.
2. Growth in body size is complete for most girls by age 16 and for boys by
age 17%2. 3. Body Proportions (p. 352)
a. At first, growth of the hands, legs, and feet accelerates, and then the
torso.
b. 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.
3. Muscle-Fat Makeup and Other Internal Changes (pp. 352-353)
a. 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.
b. Boys develop larger skeletal muscles, hearts, and lung capacity.
4. Changing States of Arousal (p. 353)
a. On average, sleep declines to 7.5 to 8 hours per night in adolescence.
Yet, teenagers need almost as much sleep as they did during the school
years-about 9.2 hours.
b. Biological changes may underlie a sleep "phase delay" because the
tendency to stay up late strengthens with pubertal maturation.
c. Sleep-deprived adolescents tend to achieve less well in school, more
often suffer from depressed mood, and report irregular sleep schedules.
D. Motor Development and Physical Activity (pp. 353-354)
1. Girls' gains in gross motor development are slow and gradual, leveling off at
age 14. Boys show a dramatic spurt in strength, speed, and endurance that
continues through the teenage years.
