A Topical Approach to LIFE-SPAN DEVELOPMENT

1. A Topical Approach toLIFE-SPAN DEVELOPMENT Chapter Three: Physical Development and Biological Aging John W. Santrock

2. Body Growth and Change • Patterns of growth • Cephalocaudal pattern – from top (head) and gradual to bottom • Proximodistal pattern – center of body outward to extremities • Growth rate affected by SES, birth order, and maternal habits during prenatal development • Growth hormone deficiency – pituitary gland

3. Changes in Proportions of the Human Body During Growth Fig. 3.1

4. Height and Weight in Infancy and Childhood

5. Body Growth and Change • Puberty • Period of rapid physical and hormonal changes • Physical changes; growth spurt • Girls – menarche, hips widen, body hair • Onset for most: 9 to 15 years of age • Boys – first ejaculation, grow taller, body hair • Onset for most: 10 to 17 years of age

6. Body Growth and Change • Puberty • Hormonal changes • Powerful chemicals from endocrine glands • Hypothalamus – eating and sexual behavior • Pituitary gland – controls growth, regulates glands • Gonads – male testes, female ovaries • Gonadotropins – stimulate testes, ovaries

7. Body Growth and Change • Puberty • Hormones increase dramatically in adolescence • Testosterone – voice change, genital growth • Dominates male changes • Estradiol – estrogen for breast growth • Dominates female changes • Onset affects social competence • Behaviors and moods can affect hormones

8. Body Growth and Change • Psychological effects of puberty, onset timing • Early maturation • Boys: positive self-image, better peer relations • Girls: similar to boys, not as strong, at more risk of behavior problems • Late maturation • Boys: developed stronger positive self-image in their 30s

9. Body Growth and Change • Early adulthood • Height is constant • Many reach peak of muscle tone and strength in late teens and twenties • Peak in joint functions in twenties • Decline in the thirties

10. Body Growth and Change • Middle adulthood • Physical appearance • Loss of height (more for women), weight gain • Skin wrinkles, sagging, aging spots appear in 40s or 50s • Hair thins and grays, fingernails and toenails thicken • Youth-oriented culture affects lifestyle changes • Baby boomers desire plastic surgery, Botox

11. Body Growth and Change • Middle adulthood • Strength, joints, and bones • Sarcopenia – muscle mass and strength loss • 1% to 2% muscle loss after age 50 • Cardiovascular system and lungs • HDL and LDL cholesterol, clogged arteries • Hypertension: blood pressure increases • Decreased lung capacity after age 55

12. Body Growth and Change • Middle adulthood • Sexuality changes • Climacteric — fertility declines • Menopause — menstrual periods ceases • Dramatic decline of estrogen; a negative experience for most women • Males do not lose fertility

13. Lung Capacity, Smoking and Age Fig. 3.4

14. Body Growth and Change • Late adulthood • Physical appearance more pronounced • Facial wrinkles, age spots • Weight loss after age 60; decreased by exercise and weight lifting • Circulatory system • Increased blood pressure, linked to chronic conditions and longevity

15. The Brain • Brain physiology • Structure and function • Forebrain • Cerebral cortex has four lobes • Frontal, occipital, temporal, parietal lobes • Deeper in brain: • Hypothalamus, pituitary gland, amygdala, hippocampus

16. The Brain’s Four Lobes Fig. 3.6

17. Functions of Lobes of the Cortex

18. The Brain • Brain physiology • Neurons— nerve cells handling information processing at the cellular level • Axon, dendrites, synapses • Neurotransmitters: dopamine • Myelin sheath and myelination • Neural circuits • Lateralization— specialization of functions in one hemisphere of cerebral cortex

19. The Neuron Fig. 3.7

20. The Brain • Infancy • Shaken Baby Syndrome • Born with about 100 billion neurons • Brain flexibility and resilience demonstrated in deprived environments • Dramatic increases of neural connections • Brain areas do not mature uniformly; skills affected by myelination and interconnections

21. The Brain • Infancy • Myelination; visual and auditory • Rapid growth of myelin sheath, dendrite and synapse connections • Blooming and pruning of connections in brain • At birth, greater activity in left hemisphere • Motor control begins about 2 months

22. Dendritic Spreading Fig. 3.12

23. The Brain • Childhood • The brain and head grow more rapidly than any other part of the body — growth curves • Some brain size increase due myelination and number and size of dendrites • Greatest anatomical brain increases from ages 3 to 15 years; distinct bursts of growth

24. Synaptic Density in Human Brain from Infancy to Adulthood Fig. 3.13

25. The Brain • Childhood • Ages 3 to 6; most rapid growth in frontal lobe • Age 6 to puberty; most dramatic growth in temporal and parietal lobes • Promotes spatial relations and language • Brain pathways and circuitry promote cognitive control (attention, thoughts, actions, choices)

26. Growth Curves for Head and Brain and for Height and Weight Fig. 3.14

27. The Brain • Adolescence • Brain continues growth • Corpus callosum – axon fibers thicken • Prefrontal cortex – increased reasoning, decision making, self-control • Amygdala – seat of emotions, matures earlier • Positive link between volume and duration of aggressive behavior toward parents

28. The Brain • Adolescence • Research on brain development and changes • Thicker prefrontal cortex, more brain connections linked to peer pressure resistance • Early ‘turbo charged’ emotions – more risky behaviors, drug use, legal system involvement? • Brain change – result of biology, experiences

29. The Brain • Adulthood and aging • Brain loss: 5-10% of weight in ages 20 to 90 • Dendrites decrease; myelin sheath damage • Shrinkage is not uniform; most in prefrontal cortex • General slowing of brain and spinal cord function • Begins in middle age, accelerates with age • Reductions in neurotransmitters

30. The Brain • The adapting brain • Exercise and activities influence development • Remarkable repair capability • Neurogenesis – new cells generated • Dendrite growth; “rewiring” to compensate loss • Less lateralization with age, more adaptation • Results of the Nun Study

31. Sleep • Infancy – sleep/wake cycle • Newborns average 16-17 hours a day • Varied patterns; longest period is 11 pm to 7 am • At 1 month – infants sleep more • At 6 mos – closer to adult-like sleep patterns • Most common problem – night waking • Culture affects sleep patterns

32. Sleep in Infancy Varied sleeping patterns Longest sleep period: 11 pm to 7 am May change from longer to shorter sleep periods Most close to adult patterns by 4 months More REM sleep than any other time of life Shared sleeping with parents is controversial Sleep

33. Sleep • REM sleep • As infant, half of sleep pattern; begins sleep cycle • May provide self-stimulation • Cannot determine if infants dream like adults • As adult, REM is 20% of sleep pattern; onset 1 hour after non-REM • Shared sleeping – controversial issue • Common outside United States and Great Britain

34. Sleep Across the Human Life Span Fig. 3.19

35. Sleep • SIDS • Infants stop breathing; most die suddenly in night • Highest cause of infant death in United States • Highest risk: ages 2 to 4 months • Best prevention: infant sleeps on its back (prone)

36. Sleep • SIDS • Risk factors: • No pacifier, soft bedding, no fan in room • Low-birth weight, sleep apnea, lower SES • Sleeping on stomach or side • Passive exposure to cigarette smoke • Another sibling died of SIDS, abnormal brain stem functioning • Higher for African American, Eskimo infants

37. Sleep • Childhood • Recommended: 11 to 13 hours each night • Sleep problems • Inadequate sleep linked to depression, school problems, disagreeable families, living in unsafe neighborhoods, father in poor health • Uninterrupted sleep and consistent patterns important – linked to behavioral problems • Nightmares and night terrors

38. Sleep • Adolescence • Inadequate sleep patterns (less than 8 hrs a day) • Linked to fatigue, moodiness, depression, more caffeine beverage use, falling asleep in school • Sleep was 9½ hours when given the opportunity • Sleep debt: try to make up lost sleep on weekend • Biological clock and hormone melatonin cause later waking and going to sleep • Starting school later would decrease absences

39. Sleep • Adolescence • Sleep deprivation and school performance • More reported illnesses and absences • More depressed, lower self-esteem • Ineffective stress management • Less exercise, unhealthy diet • Grogginess, less attentive, poor test scores • Discipline problems

40. Sleep • Adulthood and aging • Many are sleep deprived (less than 7 hrs a day) • Work, school, social, or family obligations • Many adults don’t get enough sleep • Middle age may bring sleep problems • Wakeful periods at night, less deep sleep • Many older adults go to bed and wake up earlier, • Insomnia increases in late adulthood

41. Longevity • Life span — upper boundary of life, maximum number of years an individual can live; about 120 years of age • Life expectancy — number of years that an average person born in a particular year will probably live

42. Longevity • Life expectancy • Highest in Japan – 81 years • Racial differences in the U.S. • Highest for Whites – 78 years • White females – 81 years • Females have higher expectancy than males • Begins in mid-30s, gap increases with age • Male lifestyle associated with more risks, biological factors

43. Longevity • Centenarians • Numbers increasing • More women than men; health keeps improving • Influenced by • Biology, heredity, family history, coping ability • Health (weight, diet, smoking, exercise) • Education, personality, lifestyle • Highest ratio in Okinawa

44. Risks of Dying from Cancer in Okinawa, Japan, and the United States Fig. 3.22

45. Longevity • Biological theories of aging • Four major theories • No consensus on which best explains aging

46. Biological Theories of Aging

47. The End