Transcript CHAPTER 5 HEALTH AND PHYSICAL DEVELOPMENT Learning Objectives • How is development of the endocrine system • • involved in growth across the lifespan? How do.

CHAPTER 5
HEALTH AND PHYSICAL DEVELOPMENT
Learning Objectives
• How is development of the endocrine system
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involved in growth across the lifespan?
How do the brain and the nervous system
develop across the lifespan?
What are milestones in the development of
the brain?
Building Blocks of Growth and Development
• Human growth is influenced by the interaction
of genetic and environmental factors
– Inherit a genetic propensity for height (tall,
short, medium), but the propensity is
affected by environmental influence of
nutrition (adequate or inadequate)
Building Blocks of Growth and Development –
The Endocrine System
• Endocrine glands secrete hormones directly into
the bloodstream
– Pituitary gland is the master endocrine gland
and triggers the release of hormones from all
other endocrine glands
• Pituitary produces growth hormone
– Thyroid gland influences physical growth and
development of the central nervous system
• Thyroid deficiency can affect intellectual
development and growth
Building Blocks of Growth and Development –
The Endocrine System
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Androgens (including testosterone)
– Influence the growth spurt, responsible for
development of male sex organs, contribute to sexual
motivation
Estrogen
– Influences the growth spurt, responsible for
development of breasts, pubic hair, and female sex
organs, controls the menstrual cycle
Progesterone – the “pregnancy hormone”
– Orchestrates changes that allow conception and then
supports pregnancy
Adrenal glands secrete androgen-like hormones
– Contribute to the maturation of bone and muscle and to
sexual motivation
Building Blocks of Growth and Development –
The Nervous System
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Nervous system consists of the brain and spinal cord (central
nervous system or CNS) and the body-wide neural tissue
(peripheral nervous system)
– Basic unit is the neuron
• Neurons have branching dendrites that receive signals
from other neurons and a long axon that transmits electric
signals to other neurons (or a muscle cell)
– Neuron-to-neuron connections are made at a synapse
– Axons are covered in myelin, a fatty sheath
• Myelination begins prenatally and continues for many
years
– Progressive myelination is responsible for aspects of
development such as language, abstract thinking,
concentration, and integration of thought and emotion
Caption: Parts of a neuron.
(a) Although neurons
differ in size and
function, they all
contain three main
parts: the dendrites,
which receive
messages from
adjacent neurons; the
cell body; and the axon,
which sends messages
across the synapse to
other neurons. (b) The
formation of dendrites
leading to new
connections among
existing neurons, as
well as the myelination
of neural pathways,
accounts for much of
the increase in brain
weight during a baby’s
first two years.
Building Blocks of Growth and Development –
Brain Development
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Milestones of brain development
– At birth, the brain weighs 25% of its adult weight
– By age 2, the brain weighs 75% of its adult weight
– By age 5, the brain weighs 90% of its adult weight
During early development, the brain has great
plasticity, or responsiveness to experience
– Can be highly vulnerable to damage by teratogens
– Can often recover successfully from injuries
– The critical or sensitive period for brain
development is during the late prenatal period and
early infancy
Learning Objectives
• What is lateralization? How does it affect
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behavior
How does the brain change with aging?
What principles underlie growth?
What are examples of each principle?
How can we apply a lifespan developmental
approach to our understanding of health?
Brain Development
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Lateralization in brain development
– The functions controlled by the two hemispheres diverge
• Typically, the left cerebral hemisphere controls the right side of
the body
– Adept at the sequential processing needed for analytic
reasoning and language processing; “thinking side” of the
brain
• Typically, the right hemisphere controls the left side of the body
– Skilled at the simultaneous processing needed for
understanding spatial information and for processing visualmotor information and the emotional content of information;
the “emotional side” of the brain
– The hemispheres are connected by the neurons that make up the
corpus callosum
Signs of lateralization are evident at birth
• Direction the head is turned, grasp reflex, hemispheric response to
speech sounds
Brain Development
• Brain development is never complete
– Evidence from research suggests that the
brain is responsive to experience and
capable of neurogenesis across the
lifespan
• Process of generating new neurons
Brain Development
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As a result of gradual and relatively mild degeneration within
the nervous system, the aging brain typically processes
information more slowly than does a younger brain
– Some loss of neurons, diminished functioning of neurons,
and changes to related tissues, such as myelin
• Greatest loss in the areas that control sensory and
motor activities
– Decrease in brain weight and volume
– Transmission of signals by atrophied neurons is less
effective
– Declines in levels of neurotransmitters
– Formation of “senile plaques”
– Reduced blood flow to the brain
Brain Development
• Plasticity and growth make up for
degeneration in the brain until people are in
their 70s and 80s
• A key to maintaining or improving
performance in old age is to avoid the many
diseases that can interfere with nervous
system functioning
• Another key is to remain intellectually active
Building Blocks of Growth and Development Principles of Growth
• Three principles that underlie growth
– Cephalocaudal principle
• Head-to-tail direction
– Proximodistal principle
• From the center outward to the
extremities
– Orthogenic principle
• Development starts globally and
undifferentiated and proceeds toward
hierarchal integration and differentiation
Building Blocks of Growth and Development A Lifespan Developmental Model of Health
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Health is a lifelong process
Health is determined by both genetic and
environmental influences
Health is multidimensional
• Includes physical, mental, and social wellbeing, not merely the absence of disease or
infirmity
Changes in health involve both gains and losses
Health occurs in a sociohistorical context
• Socioeconomic status is particularly important
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Learning Objectives
What is the typical pattern of growth during the
first year of life?
What is the difference between survival and
primitive reflexes? What are examples of each
type of reflex?
What other capabilities do newborns have?
How do locomotion and manipulation of objects
evolve during infancy?
What factors influence the development of
infant’s’ motor skills?
What health issues should be considered during
the first two years of life?
The Infant – Rapid Growth
• Newborns typically weigh 7 to 7½ pounds and
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are about 20 inches long
By age 2, are about half their eventual adult
height and weigh 27-30 pounds on average
Growth occurs in fits and starts and often is
accompanied by irritability
Infants whose overall weight gain outpaces
gains in height are at risk of childhood obesity
The Infant – Newborn Capabilities
• Reflexes are unlearned, involuntary
responses to stimuli
• Survival reflexes are adaptive
• Examples: breathing, eye-blink, sucking
• Primitive reflexes are less adaptive and
typically disappear in early infancy
–Examples: Babinski reflex, grasping
reflex
–Persistence of primitive reflexes can
suggest neurological problems
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The Infant – Behavioral States
Organized and individualized patterns of daily
activity that suggest the baby is integrating
biological, physiological, and psychosocial
functions
– Initial short sleep-wake cycles become more
predictable and stable between 3-6 months
– Rapid eye movement (REM) sleep
• Newborns spend 50% of their sleep in REM
• Infants older than 6 months spend 25-30%
of their sleep in REM
• May be useful for regulating sensory
stimulation
The Infant – Locomotor Development
• Developmental norms
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• Average age of mastery
Early motor development follows the
cephalocaudal and proximodistal principles
• Can sit before they can walk
• The trunk is controlled before the arms and
legs
• Gross motor skills are mastered before fine
motor skills
The Infant – Locomotor Development
• Early motor development also demonstrates
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the orthogenetic principle
• An infant will make a global response
before a differentiated response
Crawling may take many forms or may not
occur
Walking – a major milestone of about 1 year
• A more mature nervous system, more
muscle, and a less top-heavy stature are
necessary for walking
The Infant – Grasping and Reaching
• Progression from reflexive response to more
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voluntary, coordinated behavior
Infants use an ulnar grasp with palm and
fingers pressed together
Between 6 and 12 months, reaching and
grasping become more proficient
• Adjusted to the characteristics of an object
Pincer grasp is reliable by one year of age
• Thumb and forefinger
The Infant – Motor Skills as Dynamic Action
Systems
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Rhythmic stereotypies are performed before a
new motor skill emerges
• Repetitive movements such as rocking,
swaying, bouncing, mouthing objects, banging
arms up and down
Dynamic systems theory explains motor
developments
• A “self-organizing” process in which children
use the sensory feedback they receive when
they try different movements to modify their
motor behavior in adaptive ways
The Infant – Motor Skills as Dynamic Action
Systems
• According to dynamic systems theory, when
children learn to walk
• The learning takes into account their
biomechanical properties and the
characteristics of the environment they
must navigate
• Nature (the child’s central nervous system)
and nurture (sensory and motor
experiences) are essential and integral
• Action and thought are integrated
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The Infant – Health and Wellness
Typical health issues of infancy
• Health problems associated with
prematurity and low birth weight may
persist
• Complications of prematurity are second
leading cause of death; 1/3 of infant
deaths
• Congenital malformations, including
heart defects, spina bifida, Down
syndrome, cleft palate, etc. are leading
cause of death
The Infant – Health and Wellness
• Infant health has been dramatically improved
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by the administration of vaccinations against
diphtheria, pertussis, polio, and measles
• Socioeconomic status is a determinant of
access to healthcare and vaccinations
Postnatal health is enhanced by well-baby
healthcare to ensure that development is
proceeding normally and by following
recommendations for prevention of illness
Learning Objectives
• What are the typical patterns of growth and
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physical development in childhood?
What factors influence children’s health?
How can health be optimized during
childhood?
The Child – Steady Growth
• From age 2 until puberty, children gain 2-3
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inches in height and 5-6 pounds annually
Cephalocaudal and proximodistal principles
of growth continue to prevail
The Child – Physical Behavior
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Children learn to move capably in a changing
environment
By age 3, walk or run in a straight line
By age 4, perform a different activity with each
hand
Kindergartners can integrate motor skills into a
higher-level skill
Motor skills are responsive to practice
Boys are more skilled in throwing and kicking
Girls are more skilled in hopping and in manual
dexterity
The Child – Physical Behavior
• From age 3 to age 5, eye-hand coordination
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and control of small muscles improve
By age 8 or 9, children can use tools such as
a screwdriver and are skilled at games
requiring eye-hand coordination
Reaction time improves steadily throughout
childhood
The Child – Health and Wellness
• Parents’ education and socioeconomic status
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are factors that influence children’s health
Accidents are the leading cause of death
during childhood
• Motor vehicle crashes cause the most fatal
injuries
Nutrition continues to contribute to health
• Children need a well-balanced diet, but
societal influences inadvertently encourage
poor eating habits
Caption: Among white and black families, parent’s education level
influences the extent to which children’s activities are limited by poor
or fair health. Children have more limitations when their parents are
less educated. This is not true among Hispanic and Asian families.
The Child – Health and Wellness: Nutrition
• Parents can influence children’s nutrition by
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offering healthy foods and modeling healthy
eating habits
Schools influence children’s eating habits and
health
– Breakfast programs
– School lunches often have higher than
recommended levels of fat and sodium and
lower than recommended levels of fiber
The Child – Health and Wellness: Nutrition
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Regular physical activity fosters health during
childhood
• Children should have at least 60 minutes of
moderate or vigorous physical activity daily
• The average child spends 5-6 hours in
sedentary activities each day
Obesity rates have tripled over the past 30 years
and are especially high among ethnic minority
children
• Obesity – being 20% or more above the ideal
weight for one’s height, age, and sex
Caption: Increase in childhood/teen obesity
rates over a 30-year period (1976-2006)
Learning Objectives
• What physical changes occur during
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adolescence?
What factors contribute to sexual maturity of
males and females?
What psychological reactions accompany
variations in growth spurt and the timing of
puberty?
The Adolescent – The Growth Spurt
• The growth spurt is triggered by an increase
in the level of growth hormones
– Girls’ peak rates of growth
• For height – not quite 12 years of age
• For weight – 12.5 years
– Boys’ peak rates of growth
• For height – 13.4 years of age
• For weight – 13.9 years
• Girls achieve adult height around 16; boys
continue to grow until 18, 19, or 20
The Adolescent – Sexual Maturation
• Increased production of adrenal androgens
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(adrenarche) contributes to secondary sex
characteristic of pubic/axillary hair
Increased production of gonadal hormones
primarily responsible for secondary sex
characteristics and sexual maturation
“Tanner Scale” used to measure progression
through five stages of sexual maturity
• Menarche is the most dramatic event in
girls’ sexual maturation process
The Adolescent – Sexual Maturation
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Girls’ sexual maturation is influenced by ethnicity,
weight at birth, and weight gain during childhood
• The lighter a girl is at birth and the more
weight she gains during childhood, the earlier
she begins menstruating
Boys’ sexual maturation process begins at age
11-11½ with growth of testes and scrotum
• The marker of sexual maturation for boys is
semenarche, first emission of seminal fluid,
around age 13
The Adolescent – Sexual Maturation
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The rate of development during adolescence is
determined by
– Genes that trigger production of hormones
– Environment
• The secular trend
– The historical trend in industrialized
societies toward earlier maturation and
greater body size (caused by improved
nutrition and advances in medical care)
– For girls, family situation
• Presence of an unrelated male in the
household, family disruption, harsh mothering
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Sexual Maturation – Psychological
Implications
Girls become concerned with appearance
and worry about the responses of others
– Individual reactions vary widely
– May develop negative views about
menstruation and poor body images as a
result of weight gain
Boys are likely to welcome weight gain and
voice changes and to react positively to
semenarche
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Sexual Maturation – Psychological
Implications
Puberty typically prompts changes in family
relations
• Physical distancing is typical
• Teens may become more independent and
less close to parents
• Conflict is likely but about minor issues
• Family relations will be influenced by cultural
beliefs about the significance of becoming an
adult
• Parents can facilitate the adjustment to
puberty by maintaining close relationships and
helping adolescents accept themselves
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Sexual Maturation –
Early versus Late Development
Early development for boys
• Advantages – judged to be socially competent,
attractive, and self-assured
• Disadvantages – increased risk of earlier
involvement in substance use and problem
behaviors such as bullying, delinquency
Late maturation in boys
• More negative effects – more anxious, less
sure of themselves, more behavior and
adjustment problems, lower achievement test
scores
• Positive effect – less likely to use alcohol
Sexual Maturation –
Early versus Late Development
• Early development for females
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• More disadvantageous – subject of
ridicule; higher level of body dissatisfaction
• Socialization with older peer group can
lead to dating, substance use, sexual
activity.
• Girls who experience early puberty and
early sex report higher levels of depression
Late development for females
• Advantage – good school performance
• Disadvantage – some anxiety
Sexual Maturation –
Early versus Late Development
• Late-maturing boys and early-maturing girls
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are especially likely to find adolescence to be
disruptive
Differences between early and late
developers tend to fade with time
Effects of timing of puberty depend upon the
adolescent’s perception of whether puberty
events are experienced early, on time, or late
Reactions of peers and family members to an
adolescent’s pubertal changes are
instrumental in determining the adolescent’s
adjustment
The Adolescent – Physical Behavior
• Dramatic physical growth makes teens more
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physically competent, stronger, than children
Adolescents are less physically active than
they should be
- Girls are more sedentary than boys
• Gender-role socialization may be partly
responsible
The male-female gap in physical performance
among top athletes has narrowed
The Adolescent – Health and Wellness
• Many adolescents are strong, fit, and
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energetic, but 1/3 have poor physical fitness
High blood pressure, cholesterol, and blood
sugar put teens at risk for heart disease at
earlier ages
Heredity, poor eating habits, inactivity, and
parent behaviors contribute to risk for obesity
The Adolescent – Health and Wellness
• The leading causes of death among teens
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are unintentional injuries and violence
- Injuries mostly from motor vehicles
- Violence associated with homicides and
suicides
Other health risks that originate in
adolescence include alcohol and drug use
and cigarette smoking
The Adolescent – Health and Wellness
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One of four high school students report
occasional heavy or binge-drinking
Risky choices associated with alcohol use
include
– More likely to smoke and to become addicted
to nicotine
– More likely to engage in risky sexual behaviors
– More likely to get into a car where the driver
has been drinking
– More likely to get into fights, have academic
problems, and engage in illegal behaviors
Learning Objectives
• What physical changes occur during
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adulthood?
What are the psychological implications of the
physical changes that occur with aging?
What health concerns arise as adults age?
How can health of older adults be preserved?
The Adult
• The body of a mature adolescent or young
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adult is strong and fit
– Its organs are functioning efficiently
– Considered to be in peak health
But physical aging occurs slowly and steadily
over the lifespan
The Adult – Appearance and Physical
Functioning
• Only minor changes in physical appearance
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the 20s and 30s
Signs of aging are noticeable by the 40s
- Wrinkled skin, gray, thinning hair
- Extra weight or the “middle-aged spread” is
associated with slower metabolism and
insufficient physical exercise
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The Adult – Appearance and Physical
Functioning
Health burdens of obesity include heart
disease, type 2 diabetes, certain cancers, and
stroke
Healthcare cost of obesity in the U.S. is
estimated at $147 billion
Public health strategies for combating obesity
– Promoting health foods and beverages
– Discouraging consumption of
foods/beverages that add calories but not
nutrition
– Increasing physical activity
The Adult – Appearance and Physical
Functioning
• As people move into their 60s and beyond,
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they typically lose weight by losing muscle
and bone
- Due to sedentary lifestyle
Aging also involves a gradual decline in the
efficiency of most bodily systems
Handgrip strength in middle age is a good
predictor of disability and ability to function in
later life
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The Adult – Appearance and Physical
Functioning
Individual differences in physiological functioning
increase with age – measures vary widely among 70year-olds
– Not all older people have poor physiological
functioning
Reserve capacity of many organ systems declines
– Ability to respond to demands for extraordinary
output
Older adults are often less fit than younger adults
because they have less vigorous physical activity as
they age
Tire more quickly and need more time to recover
The Adult – Psychological Implications
• Aging occurs within the context of a society
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that values youth and devalues old age and
the physical changes of aging
Negative stereotypes about aging can lead to
ageism
– Prejudice against elderly people
For aging individuals, the concern seems to
be the ability to continue functioning at a
desirable level
The Adult – Psychological Implications
• The majority of people age 65 and older say
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they are in excellent, very good, or good
health
– Whites are more likely to report good
health than are blacks or Hispanics
– Relatively few older adults say they
assistance with daily activities
Most older people retain their sense of wellbeing and their ability to function
independently despite an increased likelihood
of impairments
The Adult – The Reproductive System
• Sex hormones have psychological
implications
– Men’s testosterone levels fluctuate
annually and daily
– Men with high levels of testosterone tend
to be more sexually active and aggressive
• Otherwise, no link to men’s moods or
behavior
The Adult – The Reproductive System
• Sex hormones have psychological
implications
– Cyclical changes in women’s hormone
levels are associated with premenstrual
syndrome (PMS)
• Bloating, moodiness, breast tenderness,
headaches in the days before
menstruation
• Debate about the validity of PMS
The Adult – Female Menopause
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The ending of menstrual periods is menopause
The average age is 51 and the usual age range
is 45-54
Society holds stereotypic views of menopausal
women
Experiences include hot flashes, vaginal dryness
Typically no effect upon anxiety, perceived
stress, anger, or job satisfaction
Women who experience severe psychological
problems during the menstrual transition often
had problems before menopause
The Adult – Female Menopause
• Until 2002, hormone replacement therapy
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(HRT; estrogen and progestin) was a remedy
for hot flashes and vaginal dryness
In 2002 a large study found that HRT was
associated with increased risk for breast
cancer, heart attack, and stroke
Lifestyle choices such as exercising and
getting adequate sleep may be the best
options for women
The Adult – Male Andropause
• Andropause is characterized by decreasing
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levels of testosterone and symptoms such as
– Low libido
– Fatigue and lack of energy
– Erection problems
– Memory problems
– Loss of pubic hair
Men experience fewer psychological effects
with andropause than women do with
menopause
The Adult – Slowing Down
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Walking slows with age
Motor actions – especially fine motor tasks
requiring object manipulation – are performed
more slowly and with less coordination
Cognitive tests that require speedy answers are
performed more slowly
Slowing of the nervous system explains slowed
motor and mental functioning
Reaction times of older adults vary greatly
Experience helps people compensate for a
slower nervous system
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The Adult – Disease, Disuse, or Abuse?
How to explain declines of physical
functioning across adulthood?
– Research suggests that aging in the
absence of disease has little effect on
physical and psychological functioning
– Disuse contributes to steeper declines in
physical functioning in some adults more
than others
– Abuse – excessive alcohol, high-fat diet,
smoking – contributes to declines in
functioning in some people
The Adult – Health and Wellness
• From childhood, acute illnesses become less
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frequent but chronic diseases/disorders
become more common
Many 70-and-older adults have at least one
chronic impairment
– Arthritis, hypertension
Among those who are impoverished, health
problems and difficulties in day-to-day
functioning are more common and more
severe
The Adult – Health and Wellness
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Staying healthy in older adulthood
– Exercise improves cardiovascular and
respiratory functioning, slows bone loss, and
strengthens muscles
– Exercise benefits mood and can enhance
cognitive functioning
– Physical activity is associated with a lower
incidence of depression among older adults
– Regular exercise by older adults is estimated
to delay the onset of physical disabilities by up
to 7 years
The Adult – Health and Wellness
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Osteoporosis (“porous bone”) – loss of minerals
– Results in fragile, easily fractured bones
– Nearly 1/3 of elderly adults who fracture a hip
die within one year
– Hip fractures are a leading cause of nursing
home admissions
– Osteoporosis can be prevented with a diet
sufficient in calcium during youth and by
weight-bearing exercises such as jogging or
walking
The Adult – Health and Wellness
• Osteoarthritis
– The most common joint problem among
older adults
– Results from gradual deterioration of the
cartilage that cushions the bones from
rubbing together
– Joint disease is deforming, painful, and
cause limitations of activities
The Adult – Successful Aging
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Results from a nun study – the level of education
affected longevity and health
– Those with a college degree lived longer and
were more likely to remain independent
– The risk of death among college-educated
nuns was lower at every age
– Nuns who were physically and mentally active
lived longer and were healthier than less
active nuns
– Higher language proficiency in adulthood
predicted mental functioning in late life