CHAPTER 5

THE PHYSICAL SELF

Learning Objectives

•How do the workings of the endocrine and nervous systems contribute to growth and development across the life span?

•To what extent are cells responsive to the effects of experience?

The Physical Self

•Genetic and environmental forces, e.g. height

– Average: Female 5’4”, male 5’9”

– Can be affected by malnutrition

– Catch-up growth possible

• After illness or periods of malnutrition

– More short people in cold climates

• Smaller body surface for heat loss

The Endocrine System

•Glands that secrete hormones

•Pituitary gland: The master gland

– Controls all other glands– Is controlled by the

hypothalamus– Produces growth hormone

•Testes secrete androgens like testosterone

•Ovaries secrete estrogen and progesterone

The Nervous System

•Brain Development– Largest, most

developed part at birth– Weight compared to

adult brain

• 25% at birth

• 75% at age 2

• 90% at age 5– Normal experience,

stimulation, result in normal brain

• 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.

Plasticity

•Responsiveness to experiences– Can be negative

• Vulnerable to damage• Environmental deprivation

– Can be positive• Aids in recovery from

injury• Can compensate for each

other• Can benefit from

stimulation• Allows for adaptability

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 life-span developmental approach to our understanding of health?

Brain Development

•Critical period: Late prenatal & early infancy

•Lateralization (at birth)– Left hemisphere

• Analytic reasoning, language

– Right hemisphere

• Understanding spatial information

• Visual-motor information– Corpus callosum connects

the two

Brain Development 2

•Never truly complete– Changes occur

across lifespan

•Growth spurts in infancy, childhood<,> and adolescence

•Full adult weight by about age 16

•Processing speed increases in adolescence

•Myelination continues into early adulthood

Brain Development 3

•The Aging Brain– Gradual and mild

degeneration

•Elderly adults– 5-30% fewer neurons than

younger adult– Greater loss in sensory-

motor areas– Plasticity still possible

•Main result of age is slower processing

Principles of Growth

•Procession of growth is orderly– Cephalocaudal: From head, downward– Proximodistal: From the center, outwards – Orthogenic: From global, undifferentiated to

specialized

A Life-Span Developmental Model of Health

•Health: A life-long process

•Determined by both genetic and environmental factors

•Is multi-dimensional: well-being, illness

•Changes involve both gains and losses

•Sociohistorical context: SES

Learning Objectives

•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

•Typically 7 to 7½ lbs., 20 inches long

•Period of rapid growth

•Neonatal reflexes– Survival reflexes: Clearly

adaptive• Breathing, eye-blink,

sucking/rooting– Primitive reflexes: Less adaptive

• Typically disappear by 4 months

• Babinski: Toes fan, grasping– Used diagnostically

The Infant 2•Behavioral States

– Short sleep-wake cycles at first– Establish more regularity at 3-6 months– REM sleep

• 50% of the time for newborns

• 25-30% by 6 months– May be useful for reducing stimulation– Individuality in infant patterns

The Infant 3•Strengths and weaknesses

– Sensory system intact– Ability to learn from

experience and from consequences

– Limited in capacity to move voluntarily

– Intentionality also limited

– Cannot interpret

complex stimuli

Infant Physical Behavior

•Developmental norms (see Table 5.4)– Average age of mastery

•Gross before fine motor skills

•Crawling at 7–10 months

•Walking at about 1 year

•Study of “walkers” (Siegel & Burton, 1999)

– Infants not using walkers sat up, crawled, and walked earlier

– Need sensory feedback to see feet

Physical Behavior 2

•Manipulating Objects

– Grasping reflex disappears: 2-4 mo

– Pincer grasp by 6 months

•Motor Skills

– Rhythmic Stereotypies

• Rocking, bouncing, mouthing objects, banging arms and legs

• Precede a skill then disappear

Dynamic Systems Theory

•Rhythmic stereotypes before skill emerges

• A Self-Organizing Process– Trying new movements – Use sensory feedback

•A Nature/Nurture Position– Motor milestones are

learned– Also require maturation

Learning Objective

•How are children’s motor skills advanced relative to those of infants?

•What factors influence children’s health? How can health be optimized during childhood?

The Child

•Age 2 until puberty– 2-3 inches in height, 5-6

lbs weight– Bones grow and harden– Run faster, jump higher,

and throw a ball farther– Skills very responsive to

practice– Hand-eye coordination,

fine motor, and reaction time all improve

Health and Wellness in Childhood

•Education level of parents a factor

•Nutrition: Well-balanced diet important

– High-carb foods detrimental

•Injuries, auto crashes: Leading cause of death

•Exercise: Promotes physical, cognitive, social well-being, academic skill

•Child obesity: Junk-food, TV

Learning Objective

•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?

Apache Puberty Ritual

Adolescence

•Growth spurt triggered by hormones

– Peak in height: Age 12/girls, 14/boys

•Menarche: Average age 12½

• Earlier in countries with good nutrition

• Maturation different by ethnicity

• AA and MA girls earlier than White

•Semenarche: Average age 13

• Emission of seminal fluid

Rates of Development

•Genes set the process in motion

•Hormones responsible for

changes

•Environment also important

Secular trend: Better nutrition– Earlier maturation, larger body size

Poorly nourished mature later

Heavy and tall mature earlier

Regular strenuous exercise mature later

• Sequence of Events in the Sexual Maturation of Males and females.

Psychological Implications

•Girls become concerned w/appearance

– Individual reactions vary widely

– Negative views about menstruation

•Boys likely to welcome the changes

•Family relations remain important

– Distance and conflict with parents

• Usually about only minor issues

Early versus Late Development

•Early males: Advantageous– More positive reactions from

others

•Late/males: Disadvantageous– More behavior and adjustment

problems

•Early/females: Disadvantageous– Subject of ridicule, lower self

esteem– Older peer group = problems

•Late/ females: Academic advantages

•Differences tend to fade with time

Physical Behavior•Dramatic physical growth overall

•Boys continue to improve

•Girls tend to level off or decline– Not totally explained by biology

• Gender role socialization important

• Gender performance gap has narrowed

• E.g., track, swimming, cycling records

• Girls concerned with how they look vs. what they do?

Health and Wellness in Adolescence•Obesity a continuing problem

– Higher risk: Diabetes, heart, BP problems– Poor eating habits, sedentary lifestyle

•Leading causes of death– Motor vehicles and violence

•Alcohol and drug use, cigarette smoking– Also result in risky choices

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?

The Adult

•Minor changes in the 20s & 30s

•Noticeable by the 40s– Wrinkles, gray hair, weight gain

•In the 60s: Weight, muscle, bone loss– Osteoporosis in older women

• Fair, light frame, smokers

• Calcium, exercise, (HRT?)– Osteoarthritis: Joint deterioration

Functioning and Health

•Most systems show decline with age

– Heart and lung capacity– Temperature control– Immune system and

strength– Reserve capacity

•On average, older people are less fit than younger BUT not all

• Physically active remain fit

The Reproductive System

•Beginning in adolescence– Sex hormones influence

behavior

• Male testosterone – Levels fluctuate daily

• Female estrogen & progesterone

– Monthly cycle– PMS? Expectations

vs. hormones– Calcium & Vitamin D

helpful

Menopause and Andropause•Menopause: Estrogen production declines

– Age range 45-54– Symptoms: hot flashes, vaginal dryness– Little anxiety, irritability, depression, or other stereotypes– Exercise and adequate sleep helpful

•Andropause: Decreasing testosterone– Symptoms: Libido, fatigue, erection, and memory problems

Slowing Down

•Balance difficulty affects the ability to walk, stand, sit, and turn

•Older people with strong muscles and good cardiovascular capacity can walk briskly

•Major change is slowing of the CNS– Increased RT– Novel/complex tasks more

difficult

•Physically-fit older people have quicker RT

Disease, Disuse, or Abuse?

•Birren (1963) study of men aged 65-91

– Healthy older same as younger

– Conclusion: Aging itself has little effect on physical and psychological functioning

•Disuse: “Use it or loose it!”– Includes mental exercise

•Abuse contributes to decline– Alcohol, high-fat diet, smoking

Health and Wellness in Old Age

•Acute illnesses less common

•Chronic disease more common

•Most 70-yr-olds: At least 1 chronic impairment

•Tremendous variability

•Exercise, nutrition: Lifelong benefits– Improves cardio, respiratory

functioning– Slows bone loss, strengthens

muscles– Less depression, delays disability

Diseases Common in Old Age

•Osteoporosis: Smokers, light frame, at risk

– Increase calcium– Weight-bearing exercise

•Osteoarthritis: deterioration of cartilage

•Successful aging – Both physical and mental

functioning – Positive attitude