Chapter 4

Body, Brain, and Health (p. 104)

Modified: 2025-07-02 4:06 PM CDST

• A. Building Blocks of Growth and Lifelong Health (p. 104)
• 1. Human growth is a complex process that occurs over many years and is influenced by genetic and environmental factors
• 2. Average U.S. female: 5’ 4”; average U.S. male: 5’ 10”; but great variability (tallest woman 7’ 7”, most women with Turner syndrome 4’ 8”)
• 3. Celiac disease
• 4. Inherited digestive problem in which gluten (protein found in all wheat) triggers immune response that can damage the small intestines
• 5. Prevents absorption of nutrients from food, stunts growth, and delays puberty
• 6. Treatment in form of gluten-free diet can lead to catch-up growth—body’s struggle to get back to genetically-programmed size
• B. The Endocrine System (p. 105)
  • 1. Endocrine glands secrete chemicals called hormones into bloodstream
  • 2. Pituitary gland—“master” endocrine gland located at base of brain
  • 3. Directly controlled by hypothalamus
  • 4. Triggers release of hormones from all other glands and produces growth hormone
  • 5. Growth hormones directly regulate growth
  • 6. Children lacking growth hormones unlikely to exceed 4 feet
  • 7. If started before puberty, use of synthetic grow hormones can result in near-expected adult height in children lacking normal amount of growth hormones
  • 8. Some children benefit from growth hormone therapy, while other do not
  • 9. Adults using growth hormones to improve athletic performance at risk for health issues like cardiac problems and insulin resistance
  • 10. Thyroid gland plays key role in growth and development and impact on nervous system
  • 11. Unnoticed deficiency of gland can lead to lower IQ in infants and slower growth
  • 12. Later thyroid deficiency results in slow growth but no brain damage.
  • 13. Testosterone and other male hormones (androgens) stimulate growth.
  • 14. Androgens responsible for development of male sex organs and contribute to sexual motivation
  • 15. Ovaries—female endocrine glands that produce larger quantities of the primary female hormone estrogen and of progesterone
  • 16. Key female hormones released in high quantities during adolescence
  • 17. These hormones key trigger of female growth spurt during adolescence
  • 18. Progesterone (sometimes called the “pregnancy hormone”) because it allows for conception and supports pregnancy
  • 19. Adrenal gland secretes hormones that contribute to maturation of bones and muscles in both sexes
  • 20. In adulthood, endocrine glands continue to regulate bodily processes
  • 21. Hormones help body metabolize (break down) food
  • 22. Declines associated with menopause
• C. The Brain and Nervous System (p. 106)
  • 1. The nervous system components—brain, spinal cord, and neural tissue
  • 2. Central nervous system—brain and spinal cord
  • 3. Peripheral nervous system—neural tissue extended outside central nervous system
  • 4. Neuron—basic cell unit of nervous system
  • 5. Dendrites—branches that receive signals from other neurons
  • 6. Axon—long segment of neuron in which signal is transmitted
  • 7. Synapse—gap between neurons
  • 8. Neurotransmitter—brain chemicals stored at end of the axons released across synapse
  • 9. Myelin—fatty sheath on axon that insulates and speeds neural transmission
  • 10. Myelination—process in which neurons encased in myelin
  • 11. Results in increase in speed of neural transmissions
  • 12. Myelination may be responsible for the vocabulary spurt in toddlers
  • 13. Increased myelination in prefrontal lobe corresponds to increase in hypothetical questions in adolescents
  • 14. Differences in myelination may underlie attention and concentration limits in younger individuals
  • 15. Some have linked myelination to increase in risk-taking behavior during adolescence.
  • 16. Brain has as many as 100 billion neurons
• D. Principles of Growth (p. 107)
  • 1. Cephalocaudal principle—head to tail development
  • 2. Head growth first, then trunk, and then legs
  • 3. Newborn head accounts for 25% of body; adult head accounts for 12% of body
  • 4. During first year, trunk grows fastest
  • 5. During second year, legs grow fastest
  • 6. Proximodistal principle—center outward to extremities
  • 7. Chest and internal organs before arms and then fingers
  • 8. Trunk fills out before arms
  • 9. Orthogenetic principle—global and undifferentiated to increased differentiation and hierarchical integration
  • 10. Single cell to highly specialized cells (e.g., blood)
  • 11. What begin as undifferentiated cells form functioning systems
• E. Conceptualizing Health across the Life Span (p. 108)
  • 1. The biopsychosocial model of health incorporates biological and psychological factors with social and cultural factors.

II. The Infant (p. 109)

• A. Conceptualizing Health Across the Lifespan (p. 108)
• B. Synaptogenesis is the growth of synapses and Synaptic pruning is the removal of unnecessary synapses (p. 109)
• C. Rapid Growth (p. 110)
  • 1. Typical newborn 20 inches and 7–7.5 pounds
  • 2. Early size related to prenatal experience
  • 3. Ounce per day and inch per month gain
  • 4. Age two, have attained half of adult height
  • 5. Growth is in spurts (90–95% of days are growth free)
  • 6. Soft bones ossify (harden) and become interconnected
  • 7. Infants have all of their muscles, but they will grow and strengthen
    8. Fontanelles is the space between the bones of an infant’s skull.
• D. Newborn Capabilities (p. 111)
  • 1. Newborns used to be viewed as helpless and ill prepared to cope with the world outside of womb.

Infants spend much time in REM sleep. But, do they dream? This is unknowable. The only way we know that others dream is when we wake them up. When they are awakened while in REM sleep they are more likely to report an interrupted dream than when they are awakened during the other stages of sleep. So, because infants cannot verbally report that they are dreaming, we'll never know if they are.

• E. Reflexes—unlearned, involuntary response to stimuli (p . 111)
• F. Survival reflexes—clear adaptive value
• 1. Breathing
• 2. Eye-blink (protect eye from foreign object or bright light)
• 3. Sucking (obtain food)
  • The sucking reflex changes with experience
    • early on, infants use their lips to suck
    • later, they modify their sucking behavior using their tongues and the roof of their mouths
• 4. Primitive reflexes—some unclear value, others are some adaptive value, at least in some cultures
• 5. Grasping reflex may help infants cling to caregivers
• 6. Stepping reflex may be forerunner of later voluntary behavior
• 7. Expression of primitive reflex (e.g., grasping) not related to later expression (strong voluntary grip)
• 8. Primitive reflexes typically disappear in early infancy
• 9. Useful for diagnosing neurological problems
• 10. Disappearance of primitive reflexes indicator of normal nervous system development and that experience is influencing brain and behavior
• G. Behavioral states—organized, individual patterns of daily activity (p. 111)
  • 1. Predictable sleep–wake cycles within 6 months after birth
  • 2. Newborns spend half of time in active, rapid eye movement (REM) sleep
  • 3. By 6 months, about 25–30% in sleep in REM, which more closely resembles 20% rate in adults
  • 4. REM sleep associated with brain maturation and plasticity
  • 5. Infants may sleep to regulate sensory stimulation as to not overload the immature nervous system
  • 6. To reduce stimulation, infants become less active and slip into sleep
  • 7. Sleep is important at all ages.
• H. Health and Wellness (p. 113)
  • 1. Congenital malformations—genetic or prenatal event defects present at birth
  • 2. Leading cause of death during first year
  • 3. Examples include heart defects, spina bifida
  • 4. Second leading cause of infant mortality is low birth weight
  • 5. Use of vaccinations has led to significant improvement in infants’ health
  • 6. In the United States, immunization use is highly related to socioeconomic status

III. The Child (p. 114)

• A. Steady Growth
  • 1. Steady but slower (ages two through puberty)—2–3 inches and 5–6 pounds per year
  • 2. Growth and development continue to follow cephalocaudal and proximodistal principles
• B. Brain Laterization (p. 114)
  • 1. Asymmetry and specialization of functions
  • 2. Left hemisphere controls right side of the body
  • 3. Adept at sequential (step by step) processing for analytic reasoning and language processing
  • 4. Right hemisphere controls left side of the body
  • 5. Simultaneous processing for spatial and visual-motor information and emotional content
  • 6. Lateralization evident at birth
• B. Health and Wellness (p. 116)
  • 1. Many factors impact health (e.g., parent’s education, socioeconomic status).
  • 2. Sociohistorical context also plays role in the health and well-being of a child.
• C. Accidents are a major negative influence on children’s health. (p. 116)
  • 1. Childhood marked by injuries
  • 2. Car crashes are the leading cause of childhood fatalities
  • 3. Use of seat belts helps reduce possibility of injury
• D. Nutrition is an important contributor to childhood health. (p. 116)
  • 1. As appetite diminishes, children may become picky eaters
  • 2. Fast foods are often high in carbohydrates and low in nutrition
  • 3. School children often frequent convenience stores and consume many items with empty calories (e.g., sugary foods and beverages)
  • 4. Parents’ impact
  • 5. Can model healthy eating and provide children with healthy food
  • 6. Can steer children away from sugary sodas and popular sugar-sweetened beverages
  • 7. Preschoolers who consume sugary soda between meals are more likely to become overweight
  • 8. Children may eat more “comfort foods” in stressful environments but only if they are available
  • 9. Schools can have big impact
  • 10. Students in schools with breakfast programs have healthier weights as indicated by body mass index (BMI)—marker of body fat calculated from height and weight
  • 11. School lunches as health risk
  • 12. Lunches contain more fat than breakfasts and also have high levels of fat and sodium and low levels of fiber
  • 13. Schools taking actions like removing fries and vending machine that offer fatty or sugary snacks

"Food deserts" are common in low-income neighborhoods. That means that full-fledged grocery stores are few and far in between. Notice in the Arklatex the proliferation of Dollar General stores in small towns and the loss of larger grocery stores.

• E. Physical activity fosters good health. (p. 117)

• 1. Children need 60 minutes of moderate or vigorous exercise a day.
• 2. Physical fitness may enhance cognitive functioning (including academic performance) and psychological functioning.
• 3. Participation in physical activities may positively influence self-esteem.
• 4. Contemporary lifestyles inadvertently promote inactivity.
• 5. Average child spends 5–6 hours per day watching television, playing video games, or working on the computer.
• 6. It is more common for kids to be chauffeured everywhere.
• 7. Increasing number of children meet criteria for obesity—being 20% or more above ideal weight for height, age, and sex.
  8. Obesity rates have tripled in past 30 years.
• 9. Children in neighborhoods with safe outdoor activities are less likely to be overweight.
• 10. Children who practice indoor sedentary behavior are more likely to be overweight.
• 11. Playing active video games or sports is beneficial.
• 12. Availability of portable sports equipment (in school) means more engagement in physical activity.
• 13. Some children may be predisposed by temperament to be more sedentary and resist use of playground equipment.

IV. The Adolescent (p. 118)

• A. Puberty is the process of biological change that results in attaining sexual maturity and becoming capable of reproduction.
• B. The Adolescent Brain: What’s Going On in There? (p. 118)
  • 1. Many brain changes during adolescence
  • 2. Volume of gray matter increases, peaks, and then decreases
  • 3. White matter linearly increases
  • 4. Can increased risk-taking during adolescence be attributed to brain changes?
  • 5. Part of brain related to self-control not fully matured
  • 6. Increased responsiveness to rewards
• C. The Growth Spurt (p. 118)
  • 1. Adolescent growth spurt
  • 2. Triggered by hormones
    3. Boys and girls grow at different rates.
• D. Sexual Maturation (p. 120)
  • 1. Sexual maturation due to adrenal gland activity and release of adrenal androgens (called adrenarche) and gonadal hormones
    2. Adrenarche primarily responsible for secondary sex characteristics (e.g., pubic hair)
  • 3. Menarche—first menstruation
  • 4. Normally around 12.5 years
    5. Sexual maturation impacted by ethnicity (e.g., African American earlier)
    
  • 6. For males the process begins with enlargement of testes and scrotum around age 11
  • 7. Semenarche—initial ejaculation (via “wet dream” or masturbation)8. Production of sperm typically comes after semenarche at around age 13
  • 9. Will sprout facial hair and experience the lowering of the voice (can result in embarrassment)
  • 10. Variations in timing
  • 11. Genes help determine the rate of adolescent development
  • 12. Physical and sexual maturation triggered when hypothalamus of brain stimulates endocrine system
  • 13. Boys and girls have similar levels of “male” and “female” hormones during childhood
  • 14. At sexual maturation, boys have larger quantities of male hormones (e.g., androgens)
  • 15. At sexual maturation, girls have larger quantities of female hormones (e.g., estrogen)
  • 16. Secular trend—earlier maturation and greater body size in industrial societies
  • 17. Better medical care and nutrition
  • 18. Taller and heavier girls tend to mature earlier
• E. Psychological Implications (p. 123)
  • 1. Girls experiencing puberty tend to become self-conscious about their appearance.
  • 2. Boys are more likely to welcome their weight gain and voice changes.
  • 3. Later-developing boys tend to perform poorly on school achievement tests.
  • 4. Later-developing girls outperform other students.
  • 5. Early-maturing girls have a greater likelihood of experiencing long-term adjustment problems, including anxiety and depression.
• F. Health and Wellness (p. 124)
  • 1. Only 25% of teenagers do the recommended 60 minutes of daily physical activity.
• G. Weight: being 20% or more above the “ideal” weight for height, age, and sex (p. 125)
  • 1. Obesity rates have increased over the past 15 years
  • 2. Increase in rates of diabetes—high levels of sugar in the blood leading to various health problems
  • 3. Obesity may also affect brain function through metabolic syndrome (MeTS)
  • 4. A combination of risk factors typically associated with obesity and includes high blood pressure, unhealthy cholesterol levels, and diabetes
• H. Most teens do not get the optimal amount of sleep on school nights.
  • 1. Associated with decreased motivation
  • 2. Report higher levels of depression, irritability, and lack of tolerance for frustration
  • 3. Have difficulty controlling their emotional responses

V. The Adult (p. 127)

• A. The Changing Brain (p. 127)
  • 1. Brain development is never truly complete
  • 2. Neurogenesis is the process of generating new neurons
  • 3. Hippocampus is the part of the brain involved in learning and memory
  • 4. Culture influences brain organization
  • 5. Numerous misconceptions about “normal” aging
  • 6. Brain weight and volume decrease over the adult years
  • 7. Growth of dendrites continues through adulthood
  • 8. Degeneration and plasticity characterize the aging brain
  • 9. Neurocognitive maintenance—regular upkeep of the brain
  • 10. Neurocognitive reserve—stockpile of neural resources that we save up over our lifetime
  • 11. Compensation—our ability to enlist the help of other neural resources when we are faced with a challenging task that our brain might not otherwise be able to manage
• B. The Changing Reproductive System (p. 129)
  • 1. Sex hormone levels fluctuate in both males and females
  • 2. Males fluctuate more annually
  • 3. High levels of testosterone related to aggression and sexual activity, but changes in hormone levels not clearly tied to changes in mood or behavior
  • 4. Females fluctuate more dramatically monthly
  • 5. Shifts have psychological impacts
  • 6. Estrogen and progesterone levels peak at mid-ovulation cycle
  • 7. Premenstrual syndrome (PMS)—symptoms experienced just before menstrual flow including breast tenderness, bloating, and headaches
  • 8. Some question validity of PMS
  • 9. Severe PMS (experienced by less than 5% of women) may be due to changing hormone levels
  • 10. Drugs like Prozac and supplements like vitamin D used to treat milder PMS symptoms
  • 11. Genetic and social factors (e.g., stereotypes of what women should experience) influence premenstrual and menstrual distress
• C. Menopause—ending of menstrual period in midlife (i.e., no ovulation or menstruation) (p. 130)
  • 1. Typical age range is from 45 to 54; due to drop in levels of estrogen and other female hormones creating a hormone mix more “masculine” and less “feminine” than that of premenopausal women
  • 2. Age of menopause somewhat related to when a woman’s mother reached menopause
  • 3. Physical effects include hot flashes—sudden sensation of warmth and sweating—and vaginal dryness
  • 4. Psychological symptoms (e.g., irritability and depression) vary greatly, and most women do not experience significant psychological problems
  • 5. Women who have experienced menopause tend to be more positive about it
  • 6. Despite the negative stereotypes, menopause seems to be “no big deal” for most women
  • 7. History of menstrual problems good predictor of menopause problems
  • 8. Expectation of impact also predict reaction
  • 9. Hormone replacement therapy or HRT—replacement of estrogen/progestin—was thought to compensate for loss of hormones
  • 10. HRT often relieves physical symptoms of menopause (e.g., hot flashes, vaginal dryness)
  • 11. HRT may increase risk of heart attack, stroke, or breast cancer
  • 12. Risks of HRT may outweigh benefits of use
  • 13. For those with severe symptoms, short-term HRT may be used
  • 14. Lifestyle changes like exercise and adequate sleep may be best options for menopausal women
• D. Andropause—male loss of reproductive capacity (“male menopause”) (p. 131)
  • 1. Decreased levels of testosterone
  • 2. Slower and less dramatic progression than menopause
  • 3. Symptoms include low libido, lack of energy, erection problems, memory problems
  • 4. Less active sperm (but still capable of having children)
  • 5. Erectile dysfunction often the result of medical conditions and not loss of hormones
  • 6. Seventy-and-older age group have at least one chronic impairment
  • 7. Sensory loss
  • 8. Arthritis 43% of elderly men; 54% of elderly women
  • 9. Hypertension
  • 10. Degenerative disease
  • 11. Exercise
  • 12. Aging adults feel less stressed and happier
  • 13. Can enhance their cognitive functioning
  • 14. Can delay the onset of physical disabilities by up to seven years
  • 15. Cannot halt the inevitable aging process
• E. Health and Wellness (p. 131)
  • 1. Osteoporosis—disease resulting in loss of bone mass due to loss of minerals, leaving bones more fragile and easier to fracture
  • 2. Nearly one-third of older adults with hip fracture die within one year
  • 3. Hip fracture leading cause of nursing home admissions
  • 4. Those who fall tend to restrict activity level
  • 5. Restricting activity levels can lead to further loss of bone mass and muscle
  • 6. Females with light frames, who smoke, and have a family history of osteoporosis are at risk
  • 7. Calcium intake and weight-bearing exercise beneficial for reducing osteoporosis
  • 8. HRT can be used, but there are risks
  • 9. Osteoarthritis—aging of the joints due to use that damages the cartilage resulting in pain and restricted movement
  • 10. Health disparity—exists when there is a difference in health status or health outcome that is associated with social, economic, and/or environmental disadvantage
  • 11. Culturally competent care—care that is attuned to a patient’s diversity and the cultural factors that might affect health and health care
• F. Healthy Aging (p. 133)
  • 1. Healthy aging will allow us to live a long life that is relatively free of diseases and disabilities that interfere with the quality of our life
  • 2. Snowdon (2002) had a longitudinal study of nuns (p. 134)
  • 3. Underwent annual mental and physical testing
  • 4. Access to health records
  • 5. Level of education positively impacted longevity and health
  • 6. Autobiographies written prior to study analyzed
  • 7. Healthier nuns used more complex vocabulary in autobiography
  • 8. Nuns with autobiographies with positive emotions lived longer

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