1. Chapter 3 Outline
Please note that much of this information is quoted from the text.
I. BODY GROWTH AND CHANGE
A. Patterns of Growth
1. The cephalocaudal pattern of growth is from top to bottom.
2. The proximodistal pattern of growth is from the center of the body towards
the extremities.
B. Height and Weight in Infancy and Childhood
1. Height and weight increase rapidly in infancy.
a. Infants typically double their birth weight by their fourth month and triple
it by their first birthday.
b. Infants grow about an inch a month the first year and reach approximately
1½ times their birth length by their first birthday.
2. Growth slows down during early childhood.
a. Both boys and girls slim down as the trunks of their bodies lengthen.
b. Body fat has a slow, steady decline.
c. Girls have more fatty tissue than boys; boys have more muscle tissue.
d. Growth patterns vary individually. A short stature can be due to
congenital factors, growth hormone deficiency, a physical problem that
develops in childhood, maternal smoking during pregnancy, or an
emotional difficulty.
e. Growth hormone deficiency is the absence or deficiency of growth
hormone produced by the pituitary gland to stimulate the body to grow. It
may occur anytime during infancy or childhood and necessitates hormone
injections.
C. Middle and Late Childhood
1. There is slow and consistent growth during this period.
2. Due to heredity and exercise, muscle tone increases during this period.
3. In relation to body height, head circumference, waist circumference, and leg
length decrease and bones continue to harden.
D. Puberty
1. Puberty is a period of rapid physical maturation involving hormonal and
bodily changes.
2. Sexual Maturation, Height, and Weight
a. Males and females differ in the order of development of pubertal
characteristics.
b. Marked weight gains coincide with the onset of puberty.
c. The growth spurt occurs approximately two years earlier for girls than for
boys.
3. Hormonal Changes
a. Hormones—powerful chemical substances secreted by the endocrine
glands and carried through the body by the bloodstream
i. The hypothalamus, pituitary gland, and gonads (sex glands) all
interact and play a role in puberty.
ii. Gonadotropins are hormones triggered by the pituitary gland that
stimulate the testes or ovaries to manufacture appropriate
hormones.
iii. The pituitary gland also interacts with the hypothalamus to
secrete hormones that either directly lead to growth and
skeletal maturation or produce growth effects through

2. interaction with the thyroid gland.
iv. The concentration of certain hormones increases
dramatically during adolescence and produce the
development of secondary sex characteristics.
a. Testosterone is the main hormone that dominates in
male pubertal development.
b. Estradiol is a type of estrogen that dominates in female
pubertal development.
v. The hormone-behavior link is complex.
4. Timing and Variations in Puberty
a. The age of puberty has decreased in the last century, most likely due to
better nutrition and health.
b. For most boys, the pubertal sequence may begin as early as age 10 or as
late as 13½ , and may end as early as age 13 or as late as 17.
c. For girls, menarche is considered within the normal range if it appears
between the ages of 9 and 15.
5. Psychological Accompaniments of Puberty
a. Body Image: One psychological aspect of puberty is certain for both boys
and girls, which is that adolescents are preoccupied with their bodies.
b. Early and Late Maturation: Timing of puberty may affect boys and girls
differently. Early maturing girls are at risk for a number of problems.
E. Early Adulthood
1. Joint functioning peaks in early adulthood.
2. Muscle tone and strength typically peaks in the late teens and 20s.
3. Sagging chins and protruding abdomens may appear.
4. Elasticity in muscles decrease.
5. Aches may begin to be felt in new places.
F. Middle Adulthood
1. Midlife physical changes are gradual and vary considerably across people.
2. Chronic illness depends upon genetics and lifestyle.
3. Physical Appearance
a. Typically, height decreases and weight increases during this period.
b. Skin begins to wrinkle and sag because of the loss of fat and collagen in
underlying issues.
c. Age spots can appear, hair thins and grays, nails become thicker and
brittle.
4. Strength, Joints, and Bones
a. Sarcopenia is the term given for age-related loss of muscle mass and
strength.
b. Maximum bone density occurs by the mid- to late 30s.
5. Cardiovascular System
a. Cholesterol level typically increases through the adult years.
b. Blood pressure typically rises in the 40s and 50s.
c. Metabolic syndrome, a condition characterized by hypertension, obesity,
and insulin is increasing for those in middle and late adulthood.
d. Around the age of 55, lung elasticity decreases.
6. Sexuality
a. Climacteric is the term for decreasing fertility.
b. Menopause is the term for when menstruation ceases.
c. The average age for the onset of menopause has been increasing.
d. While menopause may have negative aspects for some women, others are

3. less affected. Regardless, the loss of fertility is an important marker for
women.
e. While most men do not become infertile, there is a decline in sexual
hormone level and activity during middle adulthood.
G. Late Adulthood
1. There is an increased risk for a physical disability.
2. Physical Appearance
a. Wrinkles and age spots continue to appear.
b. Weight typically drops after the age of 60.
3. Circulatory system
a. Blood pressure should be monitored and, if high, treated.
4. Careers in Life-Span Development: Geriatric Nurse
II. THE BRAIN
A. Brain Physiology
1. Structure and Function
a. The cerebral cortex is responsible for about 80% of the brain’s volume
and is critical in perception, thinking, language, and other important
functions.
b. Each hemisphere of the cortex has four major areas called lobes. The four
lobes include the frontal, occipital, temporal, and parietal lobes.
c. Deeper in the brain lie the hypothalamus, pituitary gland, amygdala, and
hippocampus.
2. Neurons
a. An axon and dendrites are parts of a neuron.
b. Neurotransmitters are the chemical messengers in the brain.
c. Myelination increases the speed and efficiency of message transmission
from neuron to neuron.
d. Neural circuits are clusters of neurons that handle a particular type of
information.
e. Lateralization is the term that refers to specialization of function in one
hemisphere of the cerebral cortex.
B. Infancy
1. Early Experience and the Brain
a. An enriched environments allows for optimal brain development.
b. Repeated experiences help wire and rewire the brain.
2. Changing Neurons
a. The brain is 25% its adult weight at birth.
b. The brain reaches 75% its adult weight by the second birthday.
c. Two key developments during the first two years involve the increase in
myelination and connections between dendrites.
3. Changing Structures
a. The hemispheres have already started to specialize at birth.
b. The different areas of the brain develop at different rates, allowing for
different abilities—such as motor control or speech—to emerge with
development.
C. Childhood
1. During early childhood, the brain and head grow more rapidly than any other
part of the body.
a. The brain growth is due to myelination and an increase in number and size
of
dendrites.

4. 2. Children’s brains experience rapid, distinct bursts of growth. Different areas
of the brain experience these bursts of growth at different times.
3. The brain pathways and circuitry involving the prefrontal cortex continue to
increase in middle and late childhood.
D. Adolescence
1. The adolescent brain is different from the child’s brain, and it continues to
grow throughout adolescence.
2. The corpus callosum, prefrontal cortex, and amygdala all show important
growth during adolescence.
a. The amygdala develops faster than the prefrontal cortex, causing
adolescents to feel very strong emotions without the ability to control
these emotions. This can increase risk-taking behavior.
b. Researchers do not yet know for certain whether the brain changes come
first or whether the brain changes are a result of experiences with parents,
peers, and others.
3. Applications in Life-Span Development: Strategies for Helping Adolescents
Reduce Their Risk-taking Behavior
a. Beginning in early adolescence, individuals seek experiences that create
high-intensity feelings.
b. The self-regulatory skills necessary to inhibit risk taking often don’t
develop until later in adolescence or emerging adulthood.
c. Adults must monitor adolescent behavior in order to limit opportunities
for risk-taking behavior.
E. Adulthood and Aging
1. The Shrinking, Slowing Brain
a. The brain loses 5 to 10% of its weight between the ages of 20 and 90,
although recent research shows a loss of up to 15%.
i. The loss is due to a decrease in dendrites, damage to the myelin
sheath, or the death of brain cells.
ii. Some areas shrink more than others.
b. The function of the brain and spinal cord decreases in middle adulthood
and late adulthood.
c. The production of some neurotransmitters decreases with age.
d. All of these declines result in cognitive and motor declines.
2. The Adapting Brain
a. Certain activities can increase brain volume in older adults.
b. Neurogenesis, the generation of new neurons, continues in old age in
lower mammalian species. It is commonly believed that neurogenesis can
occur in humans throughout old age.
c. It appears that dendritic growth can occur in adults.
d. Older brains can rewire themselves to compensate for losses.
e. A decrease in lateralization may play a compensatory role in the aging
brain.
3. Research in Life-Span Development: The Nun Study
a. Idea density at age 22 is linked with higher brain weight, fewer incidences
of mild cognitive impairment, and fewer characteristics of Alzheimer
disease in late adulthood.
b. Positive emotions in early adulthood were linked to longevity.
c. Intellectual activity seems to keep neurons healthy and alive.
d. Folic acid may protect the brain from decline.
III. SLEEP

5. A. Infancy
1. The Sleep/Wake Cycle
a. Newborns sleep between 16 to 17 hours a day, although some sleep more
and others less.
b. By six months of age, most infants have a sleep pattern that resembles
adults—with the longest awake time being during the day.
c. American infants typically start sleeping 8 hours a night by 6 months of
age.
d. The most common infant sleep-related problem reported by parents is
night waking.
e. Infant sleep patterns vary by culture.
2. REM Sleep
a. About half of an infant’s sleep is in REM sleep—more than at any other
time in life—and infants often begin their sleep cycle with REM sleep
rather than non-REM sleep. This changes by 3 months of age.
i. REM sleep may provide self-stimulation and promote brain
development.
3. Shared Sleeping
a. Shared sleeping promotes breast feeding.
b. Shared sleeping allows the mother to respond more quickly to her infant’s
cries.
c. Shared sleeping allows the mother to detect breathing pauses that may be
dangerous.
d. The incidence of shared sleeping varies by culture.
e. Shared sleeping may increase the risk of SIDS, especially if the parents
smoke.
f. Shared sleeping is controversial.
4. SIDS
a. SIDS is the leading cause of infant death in the United States.
b. The highest risk of SIDS is between two to four months of age.
c. Sleeping on the back reduces the risk of SIDS.
d. Secondhand smoke, not sleeping with a pacifier, having a sibling who
died of SIDS, soft bedding, abnormal brain stem functioning, sleep apnea,
low birth weight, and low SES are all risk factors for SIDS.
B. Childhood
1. Most young children sleep through the night and have one daytime nap.
2. Children who do not get adequate sleep are more likely to show depressive
symptoms, have problems at school, have a father in poor health, live in a
family characterized by frequent disagreements and heated arguments, and
live in an unsafe neighborhood than children who get adequate sleep.
3. Bedtime resistance is associated with conduct problems or hyperactivity in
children.
4. Helping a child slow down before bedtime often contributes to less resistance
in going to bed.
5. Hours of Sleep
a. Preschool children should sleep 11 to 13 hours each night.
b. Children ages 5 to 12 need 10 to 11 hours of sleep.
6. Nightmares and night terrors may be experienced.
C. Adolescence
1. Only 31% of adolescents get eight or more hours of sleep on an average
school night.

6. 2. Adolescents who get inadequate sleep on school nights are more likely to feel
more tired or sleepy, more cranky, anxious, and irritable, fall asleep in school,
be in a depressed mood, and drink caffeinated beverages than their
counterparts who get optimal sleep (nine or more hours).
3. There seems to be physiological reasons for adolescents wanting to go to
sleep later and waking up later.
i. This shift in sleeping patterns should be considered by school systems
when deciding school start times.
4. Sleep deficits in adolescents are linked with depression, lower self-esteem,
ineffective stress management, lower levels of exercise, and having an
unhealthy diet.
D. Adulthood and Aging
1. Many adults are sleep deprived, needing at least 8 hours per night.
2. Beginning in their 40s, wakeful periods are more frequent and there is less of
the deepest type of sleep.
3. The amount of time laying in bed awake increases in middle adulthood.
4. The timing of sleep (earlier to bed, earlier to rise) changes beginning in
middle adulthood and continuing through late adulthood.
5. Naps in the afternoon are common for older adults.
6. Insomnia increase in late adulthood.
IV. LONGEVITY
A. Life Expectancy and Life Span
1. Life span is the upper boundary of life, the maximum number of years an
individual can live. The maximum lifespan for humans is approximately 120
years.
2. Life expectancy is the number of years that will probably be lived by the
average person born in a particular year.
i. The life expectancy for people born today in the U.S. is 78.1 years.
ii. Life expectancy varies by country and ethnicity group.
iii. Women have a longer life expectancy than men.
B. Centenarians
1. The number of centenarians is increasing at a rate of approximately 7% each
year.
2. A disproportionate number of centenarians are women, but the men are more
likely to be healthy.
3. The most important factors in longevity are heredity and family history,
health, education, personality, and lifestyle.
4. Contexts of Life-Span Development: Living Longer in Okinawa
i. Individuals live longer on the Japanese island of Okinawa than anywhere
else in the world.
ii. Some possible reasons for the longevity include diet, low-stress lifestyle,
caring community, activity, and spirituality.
C. Biological Theories of Aging
1. Cellular Clock Theory—the theory by Hayflick that cells can divide a
maximum of about 75 to 80 times and that, as we age, our cells become less
capable of dividing. Recent research has zeroed in on the telomeres on the
tips of chromosomes.
2. Free-Radical Theory—the theory that people age because unstable oxygen
molecules called free radicals are produced in the cells. Overeating increases
free-radicals and calorie restriction reduces free radicals.
3. Mitochondrial Theory—the theory that aging is due to the decay of

7. mitochondria in our cells. However, it is not known whether the defects in
mitochondria causes aging or are merely accompaniments of the aging
process.
4. Hormonal Stress Theory—the theory that aging in the body’s hormonal
system can lower resistance to stress and increase the likelihood of disease.