1. Slide 1 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. LIFE-SPAN DEVELOPMENT 3 A Topical Approach to John W. Santrock Physical Development and Biological Aging

2. Slide 2 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Patterns of Growth Cephalocaudal pattern — growth occurs first at the top—the head—and gradually proceeds from top to bottom Proximodistal pattern — growth starts at the center of the body and moves toward the extremities Body Growth and Change

3. Slide 3 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Fig. 3.1 Changes in Proportions of the Human Body During Growth Body Growth and Change

4. Slide 4 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Determinants of Puberty Heredity Hormones –Hypothalamus, pituitary gland, gonads –Androgens (testosterone) –Estrogens (estradiol) –Thyroid gland and growth effects –Cortisol may influence growth Body Growth and Change

5. Slide 5 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Puberty Period of rapid physical maturation involving hormonal and bodily changes that take place in early adolescence Two phases: –Adrenarche — changes in adrenal glands –Gonardarche Menarche Spermarche Weight and body fat Body Growth and Change

6. Slide 6 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Pubertal Growth Spurt Body Growth and Change Fig. 3.3

7. Slide 7 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Fig. 3.4 Normal Range and Average Development of Sexual Characteristics in Males and Females

8. Slide 8 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Body Image in Puberty Adolescents become preoccupied by bodies –Overall, girls less satisfied, boys more satisfied –Throughout puberty… Girls’ dissatisfaction increases — body fat increases Boys’ satisfaction increases — muscle mass increases Body Growth and Change

9. Slide 9 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Body Image in Puberty Early and Late Maturation –Early boys more positive, better peer relations –Late boys less positive but have more positive identity by 30s than early boys Body Growth and Change

10. Slide 10 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Body Image in Puberty Early and Late Maturation –Early girls more at risk for problems Smoking and drinking Depression and eating disorders Lower education and occupational attainment Early dating and sexual experiences Mental disorders and behavior problems Body Growth and Change

11. Slide 11 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Early Adulthood Physical changes may be subtle – 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 Body Growth and Change

12. Slide 12 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Middle Adulthood Physical – Lose height, gain weight – More skin wrinkling, sagging in 40s and 50s – Youth-oriented culture motivates life style changes Strength, bone density, flexibility decrease – 1 to 2 percent loss each year after age 50 –Sarcopenia: age-related loss of muscle mass Body Growth and Change

13. Slide 13 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Middle Adulthood Cardiovascular system and lungs – HDL and LDL cholesterol, clogged arteries – Hypertension: blood pressure increases – Decreased lung capacity after age 55 Sexuality changes – Climacteric — fertility declines – Menopause — menstrual periods cease Body Growth and Change

14. Slide 14 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Late Adulthood Variability in physical declines – Socioeconomic status is a big factor Physical appearance – Wrinkles, age spots, height and weight loss – Weightlifting can slow process Circulatory system – Increased blood pressure; linked to chronic conditions and longevity Body Growth and Change

15. Slide 15 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Brain Physiology Structure and function – Forebrain – Cerebral cortex has four lobes Two hemispheres usually work together and each lobe has a primary function Frontal, occipital, temporal, parietal lobes – Amygdala – Hippocampus The Brain

16. Slide 16 © 2008 The McGraw-Hill Companies, Inc. All rights reserved.

17. Slide 17 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Brain Fig. 3.7 The Brain’s Four Lobes

18. Slide 18 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Functions of Lobes of the Cortex Frontal lobes Occipital lobes Temporal lobes Involved in voluntary movement, thinking, personality, and intentionality or purpose Function in vision Active role in hearing, language processing, and memory Parietal lobes Roles in registering spatial location, attention, and motor control The Brain

19. Slide 19 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Development of the Brain By age 6, almost adult size. Brain growth spurts: coincide with changes in cognitive behavior Cerebrum, largest part of brain, divides into halves Lateralization, specialties of each hemisphere; left: language and logical thinking; right: visual and spatial functions

20. Slide 20 © 2008 The McGraw-Hill Companies, Inc. All rights reserved.

21. Slide 21 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. 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 The Brain

22. Slide 22 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Neuron The Brain Fig. 3.8

23. Slide 23 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Brain In Infancy Shaken Baby Syndrome Extensive brain development in utero – Born with about 100 billion neurons – Enriched early experiences can enhance brain growth and functioning – Brain flexibility and resilience demonstrated in deprived environments Experience determines brain connections –Enriched and deprived environments The Brain

24. Slide 24 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Brain In Infancy Changing neurons – Myelination; visual and auditory – Rapid growth of myelin sheath, dendrite and synapse connections – Blooming and pruning of connections in brain – Peak synaptic overproduction influenced by heredity and environment The Brain

25. Slide 25 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Brain In Infancy At birth, greater activity in left hemisphere specializes as infants listen to speech Motor control begins about 2 months Brain areas do not mature uniformly; skills affected by myelination and interconnections The Brain

26. Slide 26 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Dendritic Spreading Fig. 3.11 The Brain

27. Slide 27 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Brain in Childhood During early childhood, the brain and head grow more rapidly than any other part of the body — growth curves Some of brain’s increase due to mylenation and some due to increase in number and size of dendrites Greatest anatomical brain increases from ages 3 to 15 years The Brain

28. Slide 28 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Growth Curves for Head and Brain and for Height and Weight Fig. 3.13 The Brain

29. Slide 29 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Brain in Adolescence Growth still occurs in adolescence –Corpus callosum: fiber bundle thickens –Prefrontal cortex grows: reasoning, self- control, and decision making –Amygdala matures early: emotions and anger Implications for adolescent behavior, legal system, and death penalty? The Brain

30. Slide 30 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Brain in Adolescence Adolescent emotions — – Slow development of prefrontal cortex – Poor self-control; seek rewards and pleasure – Seek novelty; increased risk-taking – Lack of practical experiences; immature judgment The Brain

31. Slide 31 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Adulthood and Aging The Shrinking, Slowing Brain – Brain loss: 5-10% of weight in ages 20 to 90 – Dendrites decrease; death of brain cells – Shrinkage of prefrontal cortex – General slowing of function in brain and spinal cord begins in middle adulthood and accelerates in late adulthood – Reductions in neurotransmitters The Brain

32. Slide 32 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Adapting Brain Grows new brain cells throughout life – Extent depends on environment Dendrite growth continues in adults Brain rewires to compensate for losses Less lateralization with age, more adaptation The Brain

33. Slide 33 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Sleep in Infancy Newborns average 16-17 hours a day 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

34. Slide 34 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. SIDS Sleep –Having siblings who died of SIDS –African American and Eskimo infants –Lower SES groups –Passive exposure to cigarette smoke –Infants ages 4 to 6 wks –Sleeping on stomachs, use of soft bedding –Low birth weight; diagnosed with sleep apnea –Sleeping with pacifier Infant stops breathing, usually during night, and suddenly dies without apparent cause At highest risk

35. Slide 35 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Sleep in Early Childhood Most young children sleep through the night and have one daytime nap –Nightmares: frightening dreams are more common –Night Terrors: sudden arousal from sleep Sleep

36. Slide 36 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Sleep in Adolescence Many adolescents are not getting enough sleep; average 9½ hours when available –Like to stay up late, sleep late in mornings –Try to make up sleep debt on weekends Biological clocks have hormonal shift –Melatonin production — about an hour later each day delays sleepiness at night Sleep

37. Slide 37 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Sleep in Adolescence Sleep deprivation and school performance – Grogginess and inattentiveness – Poor test performance – Discipline problems – Reports of illness and depression – Low self-esteem –Ineffective stress management, exercise, diet Sleep

38. Slide 38 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Adulthood and Aging 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 earlier at night and wake up earlier in the morning – Afternoon naps Insomnia increases in late adulthood Sleep

39. Slide 39 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Life Expectancy and Life Span 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 Longevity

40. Slide 40 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Biological Theories of Aging Cellular Clock Theory Free-Radical Theory Mitochondrial Theory Maximum times that human cells can divide is about 75 to 80 People age because their cells’ metabolism produces unstable oxygen molecules (free radicals) Aging caused by decay of mitochondria; oxidative damage Hormonal Stress Theory Aging in body’s hormonal system can lower resistance to stress and increase likelihood of disease Longevity Fig. 3.20

41. Slide 41 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The End 3