Download 5 THE PHYSICAL SELF LEARNING OBJECTIVES After students

5
THE PHYSICAL SELF
LEARNING OBJECTIVES
After students have read and studied the material in this chapter, they should be able to answer the
following questions:
1. How do the workings of the endocrine system contribute to growth and development across the
life span?
2. How do the processes of neuron proliferation, differentiation, organization, and lateralization
contribute to infant brain development?
3. What key brain changes take place in adolescence?
4. What is the life span pattern of neuron degeneration and plasticity?
5. What is the difference between survival and primitive reflexes? What are examples of each type
of reflex? What other capabilities do newborns have?
6. How does physical growth proceed during infancy? What principles underlie growth?
7. How do brain development and experience combine to impact motor development?
8. What physical changes occur during adolescence? What factors contribute to sexual maturity of
males and females?
9. What psychological reactions accompany variations in growth spurt and the timing of puberty?
10. What physical changes (including those affecting reproduction and bone density) occur between
young adulthood and old age?
11. What nervous system changes typically occur in old age? What impact do these changes have
on behavior?
12. How can nutrition, exercise, and changes in lifestyle affect growth and development across the
life span?
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CHAPTER OUTLINE
I.
The endocrine system
A. Endocrine system-- body’s hormonal system
1. Endocrine gland-- secretes chemical hormones directly into blood stream
2. Pituitary gland
a. key endocrine gland located at base of brain
b. directly controlled by hypothalamus
c. “master” gland that triggers release of hormones from all other glands
and produces growth hormone
i. growth hormones-- directly regulate growth
3. Thyroid gland-- growth and development
4. Testes-- endocrine glands that produce testosterone and other androgens
a. testosterone-- specific male hormone important in adolescence
b. androgens-- general term for male hormones
5. Ovaries-- estrogen and progesterone
a. estrogen-- key female hormone
i. keys female growth spurt
ii. responsible for development of adult sex organs
b. progesterone-- key female hormone
i. critical for menstrual cycle
ii. larger quantities in adolescence
6. Adrenal gland-- contribute to maturation of bones and muscles
7. Endocrine glands continue function throughout life span
II.
The nervous system
A. The nervous system components-- brain, spinal cord, and neural tissue
1. Central nervous system-- brain and spinal cord
2. Peripheral nervous system-- neural tissue extended outside brain and spinal cord
3. Neuron-- basic cell unit of nervous system
a. dendrites-- branches that receive signals from other neurons
b. axon-- long segment of neuron in which signal is transmitted
c. synapse-- gap between neurons
d. neurotransmitter—brain chemicals released across synapse
e. myelin-- fatty sheath on axon that insulates and speeds neural
transmission
B.. Early brain development
1. Neural tube and “primitive” portions, then cerebral cortex
a. neural tube—bottom develops into spinal cord, top into brain
i. when bottom of tube fails to close result is spina bifida
ii. when top fails to close result is anencephaly (no brain above brain
stem) or encephalocele (potion of brain protrudes from skull)
b. cerebral cortex-- outer covering of brain
i. forms into two hemispheres
ii. allows for intelligence, perception
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C. Proliferation
1. Increase in number of neurons
a. up to 250,000 per minute during pregnancy
b. 10-20 weeks post conception most rapid proliferation
2. Increase in number of glial cells
a. support cells for neurons
3. Proliferation possible in adult brain
D. Migration
1. Movement of neurons to proper location in brain
2. Driven by genetic and biochemical environment
3. migration innermost to outermost
E. Organization
1. Differentiation of neurons
a. migration
b. different neurotransmitters produced
2. Synaptogenesis-- production of synapses
3. Brain growth spurt-- proliferation, synapse formation, and myelination
4. Neurons also dying
5. Organization influenced by experience
F. Plasticity
1. Deprivation of experience has negative impact on brain
a. Hubel and Wiesl visually deprived kittens lost function in vision
b. stabismus can affect child’s brain development and vision
2. Plasticity-- neural responsiveness to environmental experience
a. greatest in early development (late prenatal and early infancy)
G. Later brain development
1. Lateralization-- increasing dominance of one hemisphere
a. left hemisphere adept at sequential processing (language)
b. right hemisphere adept at simultaneous processing (spatial skills)
c. hemispheres connected by corpus collosum
d. if one hemisphere damaged, other may take over
e. lateralization evident at birth and may have genetic basis
f. brain growth spurts occur at times of cognitive advancement
f. myelination continues into young adulthood
H. The aging brain
1. Senility (e.g., Alzheimer’s disease) not normal part of aging
2. Gradual and mild degeneration common
a. loss of neurons
b. decreased levels of neurotransmitters
c. increased senile plaque
d. reduced blood flow to brain
2. Plasticity continues throughout life span
3. Performance on some tasks may increase in old age
III.
The infant
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A. Newborn capabilities
1. Reflexes-- unlearned, involuntary response to stimuli
a. Survival reflexes—clear adaptive value
i.. breathing, eye-blink
b. Primitive reflexes—unclear use
i. Babinski reflex (toe fanning)
ii. typically disappear in early infancy
iii. useful for diagnosing neurological problems
2. Behavioral states-- organized, individual patterns of daily activity
a. sleep-wake cycle
i. half of time in rapid eye movement (REM) sleep
ii. REM sleep may regulate levels of stimulation
b. states are highly individualized
c. sensing and learning
i. infants can learn form experience
ii. capacity to move voluntarily limited
3. Principles of growth
a. catch-up growth can occur following inadequate nutrition
b. cephalocaudal principle-- head to tail growth
c. proximodistal principle-- center outward to extremities
d. orthogenetic principle-- increasing differentiation
C. Physical behavior
1. Locomotor development
a. developmental norms-- typical age of mastery
b. gross and fine motor skills
i. gross-- large muscle (e.g., kicking)
ii. fine-- hand and feet (e.g., writing)
c. Crawling, walking, manipulating objects
d. global to differentiation to integration
e. crawling-- normally begins around 7 months
f. walking-- normally begins around 1 year
i. requires mature nervous system
ii. requires muscle development
iii. experience is critical (use of walkers may inhibit walking by
restricting visual-motor experience)
2. Manipulating objects
a. innate grasping reflex weakens
b. pincer grasp-- thumb to forefinger develops
c. increased integration and differentiation
3. Emergence of motor skills
a. rhythmic stereotypies—repetitive movement common in early infancy
b. dynamic systems approach-- use feedback to gain control of motor skills
c. walking is leaned not genetic with sensory feedback a key
IV.
The child
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A. Steady growth
1. Steady but slower (ages 2-puberty)-- 2-3 inches and 5-6 pounds per year
B. Physical behavior
1. Refinement of motor skills (initially awkward)
2. Improvements in eye/hand coordination often due to practice
3. Faster reaction times
V.
The adolescent
A. Physical growth and sexual maturation
1. Adolescent growth spurt
2. Puberty-- biological change resulting in sexual maturity and capacity to produce
children
3. Growth spurt
a. female peak growth spurt around age 12
i. females more fat in breast, hips
b. male peak growth spurt around age 13.4
i. males more muscle mass
4. Sexual maturation
a. females-- menarche (first menstruation)
b. rate differs by ethnicity
c. males-- semenarche (initial ejaculation)
d. production of sperm typically comes after semenarche
5. Variations in timing
a. genetic and hormonal influences
b. secular trend-- earlier maturation in industrial societies
i. better medical care and nutrition
c. anorexia nervosa-- eating disorder involving severe dieting
d. stress may delay sexual maturation
4. Psychological implications
a. concern with body image-- sex differences in concerns
i. boys more positive body images
b. both positive and negative reactions to sexual maturity
c. changes in relationships with parents
5. Early versus late development
a. early maturation more advantageous for boys than for girls
i. early maturing boys more socially competent, self-assured
ii. early maturing girls less popular, in older peer group
b. late maturation more disadvantageous for boys than for girls
i. late maturing boys more anxious, less athletic
ii. late maturing girls more academic
c. impact of time of maturity fades with time
d. timing-of-puberty effect mediated by adolescent’s perceptions
B. Physical behavior
1. Strength and physical competence increases
2. Boys outperform girls-- biological and social factors
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3. Gap between males and female physical skills narrowing
VI.
The adult
A. Physical appearance and structure
1. Most changes after 40
a. wrinkles, graying and thinning hair, changes in weight
b. osteoporosis-- disease resulting in loss of bone mass
i. female, small stature, smokers at risk
ii. calcium and exercise beneficial
c. ostheoarthritis-- aging of the joints due to use resulting in pain and
restricted movement
B. Functioning and health
1. Large individual variation
2. Decrease in reserve capacity-- ability of organs to respond to demand
3. Most adults can function successfully
C. Psychological implications
1. Stereotypes can lead to ageism-- prejudice against elderly
2. Reactions highly individual
D. The reproductive system
1. Hormones levels fluctuate (especially monthly in females)
a. premenstrual syndrome (PMS) in some women
i. some question validity of PMS
2. Menopause-- ending of menstrual period in midlife
a. due to drop in hormone levels
b. physical effects include hot flashes (sudden sensation of warmth and
sweating) and vaginal dryness
c. psychological effects- Variable, most not greatly affected
d. hormone replacement therapy (estrogen/progestin) used to compensate
for loss of hormones
i. HRT may increase risk of heart attack
3. The male climacteric-- loss of reproductive capacity (“male menopause”)
a. decreased levels of testosterone
b. erectile dysfunction
E. Physical behavior
1. Slowing down of nervous system and motor behavior important facet of aging
2. Difficulty with balance
3. Individual variation, many compensate for decline
D. Disease, disuse, and abuse
1. Effects of aging confounded with effects of disease, disuse or abuse
2. Aging is absence of disease little effect on physical and psychological
functioning
3. Disuse contributes to steep declines in physical functioning
4. Abuse of body (high fat diet, smoking) contributes to aging
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