CHAPTER 5
HEALTH AND PHYSICAL DEVELOPMENT
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Learning Objectives
- How is development of the endocrine system 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?
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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)
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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
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Building Blocks of Growth and Development – The Endocrine System
- 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
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Building Blocks of Growth and Development – The Nervous System
- 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
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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.
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Building Blocks of Growth and Development – Brain Development
- 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
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Learning Objectives
- What is lateralization? How does it affect 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?
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Brain Development
- 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 visual-motor 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
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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
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Brain Development
- 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
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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
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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
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- Three principles that underlie growth
Cephalocaudal principle
Head-to-tail direction
–The head is far ahead of the rest of the body during the prenatal period and accounts for about 25% of the newborn’s length and 13% of total body weight.
–The head accounts for only 12% of an adult’s height and 2% of an adult’s weight.
–During the first year after birth, the trunk grows the fastest; in the second year, the legs are the fastest growing part of the body.
Proximodistal principle
From the center outward to the extremities
–The chest and internal organs form before the arms, hands, and fingers.
–During the first year after birth, the trunk is rapidly filling out but the arms remain short and stubby until they undergo their own period of rapid development
Orthogenic principle
Development starts globally and undifferentiated and proceeds toward differentiation and hierarchal integration
–A human starts as a single, undifferentiated cell at conception. As growth proceeds, that single cell becomes billions of highly specialized cells (neurons, blood cells, liver cells, and so on). These differentiated cells become organized, or integrated, into functioning systems such as the brain or the digestive system.
Building Blocks of Growth and Development –
A Lifespan Developmental Model of Health
- Health is a lifelong process
- Health is determined by both genetic and environmental influences
- Health is multidimensional
Includes physical, mental, and social well-being, 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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Health is a life-long process.
Health is determined by both genetic and environmental influences.
Health is multi-dimensional
- Physical, mental, and social well-being, 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.
–Lower socioeconomic status is associated with poorer health and well-being and shorter life expectancy
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?
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The Infant – Rapid Growth
- Newborns typically weigh 7 to 7½ pounds and 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
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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
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The Infant – Locomotor Development
- Developmental norms
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
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The Infant – Locomotor Development
- Early motor development also demonstrates 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
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The Infant – Grasping and Reaching
- Progression from reflexive response to more 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
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The Infant – Motor Skills as Dynamic Action Systems
- 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
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Rhythmic stereotypies 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
–Behaviors that seem to emerge in a moment of time are actually the cumulative effects of motor decisions that the infant makes over a longer time.
–Motor milestones such as crawling and walking are the learned outcomes of a process of interaction with the environment in which infants do the best they can with what they have in order to achieve their goals.
–Individualistic process: neural maturation, physical growth, muscle strength, balance, and other characteristics of the child interact with gravity, floor surfaces, and characteristics of the specific task to influence what children can and cannot learn to do with their bodies.
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
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The Infant – Health and Wellness
- Infant health has been dramatically improved 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
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Learning Objectives
- What are the typical patterns of growth and physical development in childhood?
- What factors influence children’s health?
- How can health be optimized during childhood?
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The Child – Steady Growth
- From age 2 until puberty, children gain 2-3 inches in height and 5-6 pounds annually
- Cephalocaudal and proximodistal principles of growth continue to prevail
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The Child – Physical Behavior
- 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
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The Child – Physical Behavior
- From age 3 to age 5, eye-hand coordination 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
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The Child – Health and Wellness
- Parents’ education and socioeconomic status 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
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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.
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The Child – Health and Wellness: Nutrition
- Parents can influence children’s nutrition by 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
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The Child – Health and Wellness: Nutrition
- 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
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Caption: Increase in childhood/teen obesity rates over a 30-year period (1976-2006)
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Learning Objectives
- What physical changes occur during adolescence?
- What factors contribute to sexual maturity of males and females?
- What psychological reactions accompany variations in growth spurt and the timing of puberty?
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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
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The Adolescent – Sexual Maturation
- Increased production of adrenal androgens (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
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The Adolescent – Sexual Maturation
- 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
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The Adolescent – Sexual Maturation
- 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
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Sexual Maturation –
Early versus Late Development
- Early development for females
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
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Sexual Maturation –
Early versus Late Development
- Late-maturing boys and early-maturing girls 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
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The Adolescent – Physical Behavior
- Dramatic physical growth makes teens more 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
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The Adolescent – Health and Wellness
- Many adolescents are strong, fit, and 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
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The Adolescent – Health and Wellness
- The leading causes of death among teens 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
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The Adolescent – Health and Wellness
- 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
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Learning Objectives
- What physical changes occur during 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?
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The Adult
- The body of a mature adolescent or young 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
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The Adult – Appearance and Physical Functioning
- Only minor changes in physical appearance 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
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The Adult – Appearance and Physical Functioning
- As people move into their 60s and beyond, 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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- As people move into their 60s and beyond, they typically lose weight by losing muscle and bone.
- Due to sedentary life style
- Aging also involves a gradual decline in the efficiency of most bodily systems.
- Examples of systems that decline: the capacity of the heart or lungs to meet the demands of exercise, the ability of the body to control its temperature, the ability of the immune system to fight disease, or strength
- Handgrip strength in middle age is a good predictor of disability and ability to function in later life.
- Researchers found that those with weaker handgrip in middle age are more likely to have greater functional limitations and disabilities 25 years later
The Adult – Appearance and Physical Functioning
- Individual differences in physiological functioning increase with age – measures vary widely among 70-year-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
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The Adult – Psychological Implications
- Aging occurs within the context of a society 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
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The Adult – Psychological Implications
- The majority of people age 65 and older say 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 well-being and their ability to function independently despite an increased likelihood of impairments
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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
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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
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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
—-In research, many women reported little premenstrual mood change/
—-This suggests that expectations and not hormones play a role in many cases of PMS.
—Only a few women—probably fewer than 5%—experience significant PMS.
–Severe PMS may be remedied with antidepressant drugs such as Prozac.
— Milder forms of PMS may be treated with calcium and vitamin D because the low estrogen levels experienced prior to menstruation can interfere with the absorption of these substances by the body.
—Genetic endowment influences the extent to which a woman experiences both premenstrual and menstrual distress. —Social factors also play a role. Learned societal stereotypes of what women “should” experience at different phases of the menstrual cycle appear to influence what women experience and report.
The Adult – Female Menopause
- 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
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The Adult – Female Menopause
- Until 2002, hormone replacement therapy (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
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The Adult – Male Andropause
- Andropause is characterized by decreasing 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
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The Adult – Slowing Down
- 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
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The Adult – Health and Wellness
- From childhood, acute illnesses become less 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
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The Adult – Health and Wellness
- 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
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The Adult – Health and Wellness
- 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
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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
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The Adult – Successful Aging
- 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
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- Three principles that underlie growth
Cephalocaudal principle
Head-to-tail direction
–The head is far ahead of the rest of the body during the prenatal period and accounts for about 25% of the newborn’s length and 13% of total body weight.
–The head accounts for only 12% of an adult’s height and 2% of an adult’s weight.
–During the first year after birth, the trunk grows the fastest; in the second year, the legs are the fastest growing part of the body.
Proximodistal principle
From the center outward to the extremities
–The chest and internal organs form before the arms, hands, and fingers.
–During the first year after birth, the trunk is rapidly filling out but the arms remain short and stubby until they undergo their own period of rapid development
Orthogenic principle
Development starts globally and undifferentiated and proceeds toward differentiation and hierarchal integration
–A human starts as a single, undifferentiated cell at conception. As growth proceeds, that single cell becomes billions of highly specialized cells (neurons, blood cells, liver cells, and so on). These differentiated cells become organized, or integrated, into functioning systems such as the brain or the digestive system.
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Health is a life-long process.
Health is determined by both genetic and environmental influences.
Health is multi-dimensional
- Physical, mental, and social well-being, 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.
–Lower socioeconomic status is associated with poorer health and well-being and shorter life expectancy
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Rhythmic stereotypies 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
–Behaviors that seem to emerge in a moment of time are actually the cumulative effects of motor decisions that the infant makes over a longer time.
–Motor milestones such as crawling and walking are the learned outcomes of a process of interaction with the environment in which infants do the best they can with what they have in order to achieve their goals.
–Individualistic process: neural maturation, physical growth, muscle strength, balance, and other characteristics of the child interact with gravity, floor surfaces, and characteristics of the specific task to influence what children can and cannot learn to do with their bodies.
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