physical development and biological aging
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Physical Development and Biological Aging . Body Growth and Change The Brain Sleep Longevity. Body Growth and Change. Patterns of Growth. Cephalocaudal pattern: Growth occurs first at the top—the head—and gradually proceeds from top to bottom. Proximodistal pattern: - PowerPoint PPT PresentationTRANSCRIPT
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
HeredityHormones
Hypothalamus, pituitary gland, gonadsAndrogens (testosterone)Estrogens (estradiol)Thyroid gland and growth effectsCortisol may influence growth
Body Growth and Change
PubertyPeriod of rapid physical maturation involving
hormonal and bodily changes that take place in early adolescence.
Two phases:Adrenarche-changes in adrenal glandsGonardarche
• 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 PubertyBody Growth and Change
Onset of puberty beginning earlier:Norway — menarche at 17 in 1840s, now 13U.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 satisfiedThroughout puberty:
• Girls’ dissatisfaction increases-• body fat increases
• Boys’ satisfaction increases-• muscle mass increases
Body Growth and Change
Body Image in Puberty
Early and Late MaturationEarly boys more positive, better peer relationsLate 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 50Sarcopenia: 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
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 PhysiologyStructure 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
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 NeuronThe 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 SpreadingThe 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 fromages 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 thickensPrefrontal cortex grows: reasoning, self-control,
and decision makingAmygdala 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 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
Sleep Across the Human Life Span
SIDSSleep
Having siblings who died of SIDS
African American and Eskimo infants
Lower SES groupsPassive 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 availableLike to stay up late, sleep late in morningsTry to make up sleep debt on weekends
Biological clocks have hormonal shiftMelatonin 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-esteemIneffective 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
Longevity
Risks of Dying from Cancer in Okinawa,
Japan, and the United
States
Biological Theories of Aging
Cellular ClockTheory
Free-Radical Theory
MitochondrialTheory
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