Physical Development and Biological Aging  Body Growth and Change  The Brain  Sleep  Longevity

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

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

Changes in Proportions of the Human Body During Growth Body Growth and Change

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

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

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

Hormone Levels by Sex and Pubertal Stage for Testosterone and Estadiol Body Growth and Change

Pubertal Growth Spurt Body Growth and Change

Normal Range and Average Development of Sexual Characteristics in Males and Females

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

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

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

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

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

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

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

Lung Capacity, Smoking and Age

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

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

The Brain’s Four Lobes

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

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

The Neuron The Brain

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

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

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

Dendritic Spreading The Brain

Synaptic Density in Human Brain from Infancy to Adulthood

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

Growth Curves for Head and Brain and for Height and Weight The Brain

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

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

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

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

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

Sleep Across the Human Life Span

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

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

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

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

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

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

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

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

Risks of Dying from Cancer in Okinawa, Japan, and the United States

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