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

Slide 2 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Physical Development and Biological Aging Body Growth and Change The Brain Sleep Longevity

Slide 3 © 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

Slide 4 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Height and Weight in Infancy and Childhood Body Growth and Change Slower, consistent growth Muscle mass and strength increase Boys stronger, body proportions change Middle and Late Childhood Growth slows, patterns vary individually Girls slightly smaller and lighter Girls gain fat, boys gain muscle Early Childhood Average 20 inches, 7 ½ lbs at birth Triple weight by 1 year ½ adult height, 20% adult weight by age 2 Infancy

Slide 5 © 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

Slide 6 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Height and Weight in Infancy and Childhood Body Growth and Change Why some children are unusually short Congenital factors Growth hormone deficiency Physical problem developed in childhood Maternal smoking during pregnancy Emotional difficulty

Slide 7 © 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

Slide 8 © 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

Slide 9 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Hormone Levels by Sex and Pubertal Stage for Testosterone and Estadiol Body Growth and Change Fig. 3.2

Slide 10 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Pubertal Growth Spurt Body Growth and Change Fig. 3.3

Slide 11 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Fig. 3.4 Normal Range and Average Development of Sexual Characteristics in Males and Females

Slide 12 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Secular Trends in Puberty Body Growth and Change Onset of puberty beginning earlier –Norway — menarche at 17 in 1840s, now 13 –U.S. — menarche at 15 in 1840s, now 12½ White girls at average age of 10 African American girls at average age 8 to 9

Slide 13 © 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

Slide 14 © 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

Slide 15 © 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

Slide 16 © 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

Slide 17 © 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

Slide 18 © 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

Slide 19 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Body Growth and Change Fig. 3.5 Lung Capacity, Smoking and Age

Slide 20 © 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

Slide 21 © 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

Slide 22 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Brain Fig. 3.7 The Brain’s Four Lobes

Slide 23 © 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

Slide 24 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Development of the Brain Can skip pages By age 6, almost adult size. Brain growth spurts: coincide with changes in cognitive behavior Cerebellum, largest part of brain, divides into halves Lateralization, specialties of each hemisphere; left: language and logical thinking; right: visual and spatial functions

Slide 25 © 2008 The McGraw-Hill Companies, Inc. All rights reserved.

Slide 26 © 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

Slide 27 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The Neuron The Brain Fig. 3.8

Slide 28 © 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

Slide 29 © 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

Slide 30 © 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

Slide 31 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Dendritic Spreading Fig The Brain

Slide 32 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Fig Synaptic Density in Human Brain from Infancy to Adulthood

Slide 33 © 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

Slide 34 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Growth Curves for Head and Brain and for Height and Weight Fig The Brain

Slide 35 © 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

Slide 36 © 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

Slide 37 © 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

Slide 38 © 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 Findings from Nun Study The Brain

Slide 39 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Sleep in Infancy Newborns average 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

Slide 40 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Sleep Across the Human Life Span Fig. 3.18

Slide 41 © 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

Slide 42 © 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

Slide 43 © 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

Slide 44 © 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

Slide 45 © 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

Slide 46 © 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

Slide 47 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Life Expectancy Females average 80 years, 74 years for males Gender differences influenced by biological factors – extra X for females Life expectancy varies across countries U.S. men more likely to die from leading causes of death Associated with lifestyle and workplace stress Longevity

Slide 48 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Centenarians Numbers increasing; affected by – Genes, heredity, and family history – Women who have never married – Ability to cope successfully with stress – Education, health, and lifestyle – Individual personality Highest ratio in Okinawa Longevity

Slide 49 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Longevity Fig Risks of Dying from Cancer in Okinawa, Japan, and the United States

Slide 50 © 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

Slide 51 © 2008 The McGraw-Hill Companies, Inc. All rights reserved. The End 3