1. Slide 1 © 2005 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 © 2005 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 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Height and Weight in Infancy and Childhood Body Growth and Change Infancy Average 7 pounds, 20 inches at birth Triple weight by 1 year, 1/4 adult weight by age 2 35 inches by age 2 Early Childhood Growth slows Patterns vary individually Middle/Late Childhood Slow, consistent growth Muscle and strength increase

4. Slide 4 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Puberty A gradual process involving multiple distinguishing events. Physical, psychological and social changes. Two phases: –Adrenarche - changes in adrenal glands –Gonardarche Menarche Spermarche Body Growth and Change

5. Slide 5 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Determinants of Puberty Heredity Hormones –Androgens –Estrogens Weight and Body Fat Environmental influences: secular trend Body Growth and Change

6. Slide 6 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Hormone Levels by Sex and Pubertal Stage for Testosterone and Estadiol Body Growth and Change

7. Slide 7 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Pubertal Growth Spurt Body Growth and Change

8. Slide 8 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Development of Sexual Characteristics - Males

9. Slide 9 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Development of Sexual Characteristics - Females

10. Slide 10 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Body Image in Puberty Adolescents become preoccupied by bodies –Girls less satisfied, boys more satisfied Early and Late Maturation –Early boys more positive –Late boys more positive identity by 30s –Early girls positive but potential problems –Late girls more positive about bodies in late adolescents Body Growth and Change

11. Slide 11 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Early Adulthood Many reach peak of muscle tone and strength in late teens and twenties –Decline in the thirties Body Growth and Change

12. Slide 12 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Middle Adulthood Lose height, gain weight Physical appearance concerns in youth- oriented culture Strength, bone density, flexibility decrease Cholesterol, blood pressure rise Sexuality changes –Climacteric—fertility declines –Menopause—woman’s menstrual periods cease Body Growth and Change

13. Slide 13 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Late Adulthood Variability in physical declines –Socioeconomic status is a big factor Continue to lose height, lose weight –Weight lifting can slow muscle decrease Wrinkles continue, age spots Lungs start to stiffen around age 55 Blood pressure can rise Body Growth and Change

14. Slide 14 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Changes in Body Composition with Age Body Growth and Change

15. Slide 15 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Brain Physiology Neuron—nerve cell that handles information processing at the cellular level. Parts of the neuron: –Dendrites receive info from other neurons –Soma contains nucleus –Axon transmits message to other neurons via neurotransmitters The Brain

16. Slide 16 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. The Neuron The Brain

17. Slide 17 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Cerebral Cortex Cerebral cortex makes up 80% of brain volume and is critical to perception, thinking and language. Lateralization—specialization of functions in one hemisphere of cerebral cortex

18. Slide 18 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. The Human Brain’s Hemispheres The Brain

19. Slide 19 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. The Brain’s Four Lobes The Brain

20. Slide 20 © 2005 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

21. Slide 21 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. The Brain in Infancy Enriched early experience can enhance brain functioning Neurons change –Myelination: growth of fatty insulation around axons improves neural efficiency –Rapid growth and pruning of dendrites and connections Left hemisphere active as infants learn language Frontal cortex develops to allow motor control The Brain

22. Slide 22 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Dendritic Spreading

23. Slide 23 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Changes in Synaptic Density with Age

24. Slide 24 © 2005 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 Some of brain’s increase due to myelination and some due to increase in number and size of dendrites The Brain

25. Slide 25 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Brain and Body Growth

26. Slide 26 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. The Brain in Adolescence Spurts in EEG activity seem to occur at about 9, 12, 15, and 18 to 20 years –May signal changes in cognitive development Pruning of synapses continues into late adolescence Amygdala and hippocampus increase –May affect emotional development The Brain

27. Slide 27 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. The Shrinking, Slowing Brain General slowing of function in brain and spinal cord begins in middle adulthood and accelerates in late adulthood Reductions in neurotransmitters –Acetylcholine - memory –Dopamine - planning, motor activities –GABA - vision, thinking The Brain

28. Slide 28 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. The Adapting Brain Grows new brain cells throughout life –Extent depends on environment Dendrite growth continues through 70s More myelination between frontal cortex and limbic system facilitates reflection Less lateralization with age

29. Slide 29 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Sleep: Infancy Average 16-17 hours a day –Ranges from 10 to 21 More REM sleep than any other time of life Shared sleeping with parents is controversial Sleep

30. Slide 30 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Sleep Across the Human Life Span

31. Slide 31 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. SIDS Occurs when an infant stops breathing and suddenly dies without an apparent cause. American Academy of Pediatrics recommends putting infants to sleep on their backs to reduce the risk of SIDS. Other risk factors: low birth weight, second- hand smoke, low SES, siblings who died of SIDS Sleep

32. Slide 32 © 2005 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 –Night Terrors Sleep

33. Slide 33 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Sleep in Adolescence Many adolescents are not getting enough sleep –Try to make up sleep debt on weekends Biological clocks shift –Melatonin production about an hour later each day delays sleepiness at night –Some school districts delay class times to accommodate this shift Sleep

34. Slide 34 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. Adulthood, Aging and Sleep 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 Insomnia increases in late adulthood Sleep

35. Slide 35 © 2005 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 Life expectancy—number of years that average person born in a particular year will probably live Longevity

36. Slide 36 © 2005 The McGraw-Hill Companies, Inc. All rights reserved. The Young-Old, the Old-Old, and the Oldest-Old Young-old (65 to 74 years) Old-old (75 years and older) Oldest old (85 and over) –Many experts on aging prefer to talk about such categories in terms of function, rather than age Longevity

37. Slide 37 © 2005 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 Hormonal Stress Theory Aging in body’s hormonal system can lower resistance to stress and increase likelihood of disease Longevity