Body Brain and Health Notes PDF

BODY BRAIN AND HEALTH- NOTES 4.1 ENDOCRINE SYSTEM The endocrine, or hormonal, system consists of a group of endocrine glands, that secrete chemicals called hormones directly into the bloodstream. PITUITARY GLAND: Directly controlled by the hypothalamus of the brain, it triggers...

BODY BRAIN AND HEALTH- NOTES 4.1 ENDOCRINE SYSTEM The endocrine, or hormonal, system consists of a group of endocrine glands, that secrete chemicals called hormones directly into the bloodstream. PITUITARY GLAND: Directly controlled by the hypothalamus of the brain, it triggers the release of hormones from all other endocrine glands by sending hormonal messages to those glands. Moreover, the pituitary produces growth hormone, which triggers the production of specialized hormones that directly regulate growth. THYROID GLAND: The thyroid gland also plays a key role in physical growth and development and in the development of the nervous system. Thyroid deficiency during infancy and childhood can also lead to intellectual disability and slow growth if unnoticed and untreated. ANDROGENS: The testes of a male secrete large quantities of testosterone and other male hormones (called androgens). These hormones stimulate the production of growth hormone, which in turn triggers the adolescent growth spurt. Androgens are also responsible for the development of the male sex organs and contribute to sexual motivation during adulthood. ESTROGEN: Estrogen increases dramatically at puberty, stimulating the production of growth hormone and the adolescent growth spurt, much as testosterone does in males. It is also responsible for the development of the breasts, pubic hair, and female sex organs and for the control of menstrual cycles throughout a woman’s reproductive years. PROGESTERONE: Is the “pregnancy hormone” because it orchestrates bodily changes that allow conception and then support a pregnancy. ADRENAL GLANDS: Finally, the adrenal glands secrete androgen-like hormones that contribute to the maturation of the bones and muscles in both sexes. The maturation of the adrenal glands during middle childhood results in sexual attraction well before puberty in both boys and girls and relates to sexual orientation in adulthood. The endocrine system, in collaboration with the nervous system, is centrally involved in growth during childhood, physical and sexual maturation during adolescence, functioning over the life span, and aging later in life. 4.2 BRAIN AND NERVOUS SYSTEM The nervous system consists of the brain and spinal cord (central nervous system) and the neural tissue that extends into all parts of the body (peripheral nervous system). Its basic unit is a neuron. The axon of one neuron makes a connection with another neuron at a tiny gap called a synapse. By releasing neurotransmitters stored at the ends of its axons, one neuron can either stimulate or inhibit the action of another neuron. The axons of many neurons become covered by a fatty sheath called myelin, which acts like insulation to speed the transmission of neural impulses. The process of myelination—neurons becoming encased in this protective substance that speeds transmission—begins prenatally but continues for many years after birth, proceeding from the spinal cord to the hindbrain, midbrain, and forebrain. Myelination in the visual cortex is largely complete by age 1, consistent with advances in visual skills over the first year Toddlers experience a vocabulary spurt following a period of rapid myelination of those parts of the brain involved in language development and teenagers begin to reason about abstract concepts, such as truth and justice, owing to myelination within the prefrontal lobes during adolescence Progressive myelination of the pathways involved in attention and concentration helps explain why infants, toddlers, school-age children, and even young adolescents have shorter attention spans than do older adolescents and adults. 4.3 PRINCIPLES OF GROWTH CEPHALOCAUDAL PRINCIPLE: you have probably noticed that young infants seem to be all head compared with older children and adults. This is because growth follows the cephalocaudal principle, which means growth occurs in a head-to-tail direction. The head is far ahead of the rest of the body during the prenatal period and accounts for about 25% of the newborn’s length and 13% of total body weight. PROXIMODISTAL PRINCIPLE: While infants are growing from the head downward, they are also growing and developing muscles from the center outward to the extremities. This proximodistal principle of  growth can be seen during the prenatal period, when the chest and internal organs form before the arms, hands, and fingers. ORTHOGENETIC PRINCIPLE: This means that development proceeds from general and undifferentiated and moves toward more complex differentiation and hierarchical integration. Consider a human who starts as a single, undifferentiated cell at conception. As growth proceeds, that single cell becomes billions of highly specialized cells (neurons, blood cells, liver cells, and so on). These differentiated cells become organized, or integrated, into functioning systems such as the brain or the digestive system. 4.4 CONCEPTUALIZING HEALTH ACROSS LIFE SPAN Among the many things we have learned is that health is multidimensional and incredibly complex. The biopsychosociocultural model of health that incorporates biological and psychological factors with social and cultural factors. Biological factors include how your body responds to stress, its immune function, and how it metabolizes food and nutrients. Health also depends on your personality, emotions, coping skills, and beliefs. Perhaps you have heard of the so-called “happy hormones” consisting of dopamine, serotonin, oxytocin, and endorphins. These hormones can be elevated by sunshine, exercise, laughing with friends, and even petting your favorite furry animal. The social and cultural contexts of our lives also influence our health. Throughout infancy and childhood, we are at the mercy of our family circumstances and how our parents treat us, feed us, and care for us. At one extreme, families may be abusive or neglectful. Fortunately, most families are not this extreme, but children’s health can be influenced by other family factors. 4.5 THE INFANT Infancy is characterized by continued brain development, rapid growth, and impressive sensory and reflexive capabilities. The synaptogenesis, or growth of synapses, during childhood as well as the synaptic pruning, or removal of unnecessary synapses, is also an important component of brain development. The development of the brain early in life is heavily influenced by the unfolding of a genetic program that has evolved over man generations. In most cases, infants have opportunities to explore and experience the world, which is just what the brain needs to develop normally. During the early brain development spurt that begins before birth and continues during infancy, the brain is fine-tuned by experience through the dual processes of synaptogenesis and synaptic pruning. Brain plasticity is greatest early in development, suggesting that there is a sensitive period for brain development beginning in the late prenatal period and lasting until sometime in childhood. During this time, growth proceeds rapidly, which offers a multitude of opportunities for early experience to mold the architecture of the brain. However, the organization of synapses within the nervous system continues to change in response to experience throughout the life span. 4.6 RAPID GROWTH Newborns are typically about 20 inches long and weigh 7–7½ pounds. Although we usually think of growth as a slow and steady process, daily measurements of infant length show that babies grow in fits and starts. In the end, 90–95% of an infant’s days are growth free, but their occasional bursts of physical growth add up to substantial increases in size. At birth, most bones are soft, pliable, and difficult to break. They are too small and flexible to allow newborns to sit up or balance themselves when pulled to a standing position. The fontanelles is space between the bones of an infant’s skull. The space consists of soft cartilage-like tissue, which gradually ossifies or hardens into bony material as calcium and other minerals are  deposited into them. In addition, more bones develop, and they become more closely interconnected. As for muscles, young infants are relative weaklings. Although they have all the muscle cells they will ever have, their strength will increase only as their muscles grow. 4.7 NEWBORN CAPABILITIES 4.7.1 REFLEXES A reflex is an unlearned and involuntary response to a stimulus, such as when the eye automatically blinks in response to a puff of air. These seemingly simple reactions are actually quite varied and complex patterns of behavior that provide infants with a way to begin interacting with their world. Some reflexes are called survival reflexes because they have clear adaptive value. Examples include the breathing reflex (useful for obvious reasons), the eyeblink reflex (which protects against bright lights or foreign particles), and the sucking reflex (needed to obtain nourishment) In contrast, primitive reflexes are not clearly useful; many are believed to be remnants of evolutionary history that have outlived their purpose. The Babinski reflex is a good example. Some reflexes do have some adaptive value atleast in some cultures such as the grasping reflex. Primitive reflexes typically disappear during the early months of infancy. These primitive reflexes are controlled by the lower, subcortical areas of the brain and are lost as the higher centers of the cerebral cortex develop and make voluntary motor behaviors possible. The existence of reflexes at birth tells them that infants are ready to respond to stimulation in adaptive ways. The disappearance of certain reflexes tells them that the nervous system is developing normally and that experience is affecting both brain and behavior. For some children, primitive reflexes may linger beyond their period of usefulness and their continuation may impede the development of normal motor skills. Among adults, the presence of reflexes such as the Babinski may indicate problems with the corticospinal tract, the body’s communication system from the cortex to the spinal cord. 4.7.2 BEHAVIOURAL STATES Infants exhibit at least six behavioral states: Deep (or quiet) sleep—the infant is very still and largely oblivious to sensory stimulation going on around her Active (or light) sleep—you may see rapid eye movements and the infant may wake easily to sounds or activity going on in the surrounding environment Quiet alert—there is very little body movement; infant’s eyes are focused and is engaged with environment or caregiver Active alert—the body is active; eyes are less focused; if activity continues and sensory stimulation increases, this state can soon devolve into fussiness Drowsy—the body is relaxed with few movements; could easily transition to sleep Crying—often occurs when infant is overstimulated, hungry, or otherwise uncomfortable.  Newborns spend half of their sleeping hours in active sleep, also called REM sleep (for the rapid eye movements that occur during it) Sleep patterns in infancy are associated with brain maturation and plasticity. REM sleep, in particular, may be important for learning and memory processes. Infants are taking in vast amounts of new information during the times they are awake. These periods are invariably followed by sleep, which may help their brains learn and remember the new information. If deprived of sleep, infants may become “overloaded” with too much new information that their immature nervous systems cannot fully process. The infant’s nervous system can be overstimulated by the flood of stimulation received during the day. Somehow, the arousal needs to be reduced—perhaps by crying and then sleeping. Infants must move from short sleep–wake cycles distributed throughout the day and night to a pattern that includes longer sleep periods at night with longer wake periods during the day. Settling into an organized sleep–wake pattern is an indication that the baby’s nervous system is developing as expected and is beginning to integrate a myriad of external signals with internal states. These early sleep patterns are indicative of other behaviors. For instance, among premature infants, those who transition smoothly from one state to another exhibit more mature neurocognitive outcomes than other premature infants. 4.8 HEALTH AND WELLNESS (INFANT) Infants who are exclusively breastfed for at least 3 months have increased myelination in their brains associated with stronger cognitive skills in early childhood relative to infants who were bottle fed. Creating myelin is best accomplished when diets are high in long- chain polyunsaturated fatty acids such as those found in foods such as walnuts, salmon, and breast milk as well as some other nutrients typically found in breast milk. Although formula is a good substitute for breast milk, the composition of formula varies from breast milk and also varies across different formula brands.  Thus, in cases where breastfeeding is not possible, formula is a viable option, particularly if the nutritional composition of the formula is as close as possible to breast milk. The most common causes of mortality during infancy are as follows: Congenital malformations: 118 deaths per 100,000 live births Low birth weight: 97 deaths per 100,000 live births Maternal complications: 36 deaths per 100,000 live births Sudden infant death syndrome: 35 deaths per 100,000 live births Unintentional injuries: 31 deaths per 100,000 live births Cord and placental complications: 19 deaths per 100,000 live births. Congenital malformations, defects that are present at birth either from genetic factors or prenatal events, pose the greatest risk. These include a wide range of problems caused by chromosomal abnormalities, neural tube deficits, heart defects, cleft lip and/or palate, and other factors, many of which are never fully understood. The second leading cause of mortality, and a significant contributor to health issues during infancy, is low birth weight, which typically occurs in the context of premature delivery. The health problems associated with premature delivery and low birth weight often continue to challenge infants throughout their first year and beyond, indicating that some events can have lifelong effects on health. Infant health has been dramatically improved in recent decades by administering vaccinations aimed at protecting infants from a variety of diseases such as diphtheria, pertussis, polio, and measles. Health after birth is enhanced by well-baby visits to the doctor to ensure that development is proceeding normally and by following recommendations for prevention of illness. Quality and pattern of sleep is an important indicator of nervous system development and is associated with behaviors in childhood. 4.9 BRAIN LATERALIZATION One important feature of the developing organization of the brain is the lateralization, or asymmetry and specialization of functions, of the two hemispheres of the cerebral cortex. Instead of developing identically, the functions controlled by the two hemispheres diverge.  In most people, the left cerebral hemisphere controls the right side of the body and is adept at the sequential (i.e., step-by-step) processing needed for analytic reasoning and language processing. The right hemisphere generally controls the left side of the body and is skilled at the simultaneous processing of information needed for understanding spatial information and processing visual–motor information as well as the emotional content of information. The left hemisphere is often called the thinking side of the brain, whereas the right hemisphere is called the emotional brain. The hemispheres “communicate” and work together through the corpus callosum, “the super-highway of neurons connecting the halves of the brain”. The left hemisphere is considered the seat of language because it controls word content, grammar, and syntax, but the right hemisphere processes melody, pitch, sound intensity, and the affective content of language. If one hemisphere is damaged, it may be possible for the other hemisphere to “take over” the functions lost. Overall, then, the brain appears to be structured very early so that the two hemispheres of the cortex will be capable of specialized functioning. 4.10 HEALTH AND WELLNESS (CHILD) 4.10.1 ACCIDENTS Childhood is unfortunately marked by numerous accidents and injuries, making these the leading cause of death throughout the childhood years. Parents can reduce the possibility of accidental drownings by adding fences and coverings to swimming pools and hot tubs and closely monitoring their toddlers around all sources of water, including the bathtub. As well, motor-vehicle fatalities may be reduced by properly strapping infants and young children into car seats or, as they get older, insisting that they sit in the backseat with a shoulder-strap seat belt. Falls and being struck by something cause the largest number of nonfatal injuries during childhood, followed by such things as beestings, bites, cuts, and overexertion. Most of these injuries are minor and do not constitute a major developmental obstacle. 4.10.2 NUTRITION Nutrition continues to be an important contributor to health throughout childhood, as it was during the prenatal period and infancy. Parents can help children to become healthy eaters by regularly offering a variety of healthy foods and beverages and by modeling healthy eating habits. More education may translate into greater awareness of healthy habits. Also important is the larger environment—the neighborhood and school—of the child. Neighborhoods with higher levels of poverty and lower education levels are associated with higher rates of obesity. Students who attend schools with breakfast programs have healthier weights than students in schools without breakfast programs, as indicated by the body mass index (BMI) which is calculated using height and weight. 4.10.3 PHYSICAL ACTIVITY Children should do at least 60 minutes of moderate or vigorous physical activity every day. Unfortunately, our contemporary lifestyles may inadvertently promote physical inactivity, which may explain why the fitness levels of children have shown a measurable decline in recent years. As time in front of electronic screens has increased, many schools have reduced recess time and physical education requirements. Some children are predisposed by temperament to lead more sedentary lifestyles and resist even the most engaging playground equipment and incentives to be physically engaged. Thus, characteristics of the environment in combination with characteristics of the child affect activity levels. 4.11 THE ADOLESCENT BRAIN Magnetic resonance imaging (MRI) studies show that the brain’s “gray matter,” made up primarily of glial cells, cell bodies, and dendrites, undergoes change in an inverted-U pattern across late childhood and adolescence. That is, the volume of gray matter increases, peaks, and then decreases throughout the teen years.  This pattern is believed to be associated with increased synaptogenesis just before puberty, followed by a period of heightened pruning of synapses. Gray matter helps us process information White matter makes up a larger portion of the brain than gray matter and supports communication within and between areas of gray matter and other parts of the body. There is evidence that the limbic reward system in the brain matures earlier than the prefrontal control areas of the brain. This difference in maturity levels sets the stage for adolescents to be drawn toward actions that are rewarding, as well as risky, without fully engaging in the cognitive processing that might help them evaluate the reward relative to its associated risks. Adolescents often display poor judgment and decision making when it comes to alcohol, drug, and cigarette use; sexual activity; and driving. Although adolescents as a group may be more prone to risk-taking behaviors, it is certainly not the case that all adolescents engage in the same level of risk taking. Teens with stronger working memory skills, for instance, are less likely to take risks than their peers with weaker working memory skills. In addition, a positive relationship between teens and their parents can help protect them during this period of development. Instead of trying to change how teenagers think, Steinberg argues that we should restructure their environments to reduce their exposure to risky situations until their brains have a chance to mature more fully.\ 4.12 THE GROWTH SPURT The adolescent growth spurt is triggered by an increase in the level of growth hormones circulating through the body during adolescence. Muscles also develop rapidly in both sexes, with boys normally gaining a greater proportion of muscle mass than girls do. Total body weight increases in both sexes, but it is distributed differently: Girls gain extra fat, primarily in the breasts, hips, and buttocks; boys develop broader shoulders. 4.13 SEXUAL MATURATUTION The adrenal glands increase production of adrenal androgens sometime between the ages of 6 and 8 in both boys and girls. Known as adrenarche, this circulation of adrenal hormones contributes partly to such secondary sex characteristics as pubic and axillary (underarm) hair. The more obvious signs of sexual maturity emerge with increased production of gonadal hormones (those produced by the testes or ovaries): androgens in males and estrogen and progesterone in females. The gonadal hormones are primarily responsible for the development of secondary sexual characteristics and sexual maturity This increased hormone production will also trigger sexual thoughts, feelings, and maturation. Menarche- the first menstruation. Menstruation is the process of shedding the lining of the uterus in preparation for support of a fertilized egg. Sexual maturation also proceeds at different rates in different ethnic groups. Several studies have found that African American and Mexican American girls begin to experience pubertal changes earlier than European American girls. Genes determine an adolescent’s development: Identical twins typically begin and end their growth spurts at very similar times, and early or late maturation tends to run in families. In both sexes, the changes involved in physical and sexual maturation are triggered when the hypothalamus of the brain stimulates activity in the endocrine system. Physical and sexual maturation, then, are processes set in motion by the genes and executed by hormones. But the environment also plays its part in the timing of maturation. This is dramatically illustrated by the secular trend—the historical trend toward earlier maturation and greater body size. Better nutrition, advances in medical care, higher rates of obesity, and exposure to a wide of chemicals that may alter hormone production are the major contributing factors that explains the secular trend. Family situations can also affect the timing of puberty, atleast for girls. For instance, research has often found a correlation between earlier onset of puberty among girls and absence of their biological  father from the home such as might occur when parents separate or divorce. Truly, then, physical and sexual maturation are the products of an interaction between heredity and environment, with some environments delaying maturation and others hastening it. 4.13.1 PSYCHOLOGICAL IMPLICATIONS GIRLS: 1. Girls approaching or experiencing puberty tend to become self- conscious about their appearance and worry about how others will respond to them. 2. Some girls develop poor body images, possibly because they are bothered by the weight gains that typically accompany menarche. 3. Girls going through puberty report lack of energy and lower levels of activity, perhaps as a result of the hormonal changes but possibly also a result of their increased feelings of self- consciousness. 4. It is also the case that many girls exhibit mood changes and increased likelihood of depression and eating disorders as they proceed through puberty. BOYS: 1. Their body images are more positive than those of girls, and they are more likely to welcome their weight gain and voice changes. 2. Boys who experience slow growth and/or short stature can experience a rocky emotional road during adolescence as the smallest kid in the class, the last picked for sports, and the one least likely to be noticed in a romantic way by peers who are more developed. 3. As they proceed through puberty, though, boys show a decrease in anxiousness and feelings of worthlessness, perhaps because their size and appearance catches up with their peers. Adolescents and their parents need to restructure the parent– child relationship as the child becomes an adult and more independent (Branje, 2018). This often means more conflicts with their parents during adolescence but, in most cases, these conflicts are about minor issues such as unmade beds, late hours, and loud music rather than about core values.  4.13.2 EARLY VS LATE DEVELOPMENT Early-developing boys are judged to be socially competent, attractive, and self-assured, and they enjoy greater social acceptance by their peers. But early maturity for boys also has its downsides, namely increased risk of earlier involvement in substance use and other problem behaviors such as bullying, aggression, and delinquency. Late-maturing boys tend to experience greater anxiety and depression. On the positive side, late-maturing boys are less likely to drink alcohol or use drugs during adolescence. The early-maturing girl expresses higher levels of body dissatisfaction than her prepubertal classmates and may engage in unsafe dieting and exercising as a result of this discomfort. Early maturity seems to alter girls’ social environments, thrusting them into socializing with older peers, at least when they are outside of the highly age-organized setting of their classrooms. As a result, they are likely to become involved in dating, smoking, drinking, having sex, and engaging in minor troublemaking at an early age. Late-maturing girls (like late-maturing boys) may experience some anxiety as they wait to mature, but they do not seem to be as disadvantaged as late-maturing boys. Later-developing girls tend to perform better on school achievement tests relative to early- maturing girls, perhaps because they focus on academic skills when other girls have shifted some of their focus to extracurricular activities. 4.14 HEALTH AND WELLNESS (ADOLESCENT) WEIGHT 1. Adolescents have more sedentary lifestyles and consume more empty calories than they need, often in the form of beverages. 2. Adolescents who drink more calorie-dense, nutrient-poor beverages not only gain weight, they have higher systolic blood pressure. 3. Rates of diabetes—high levels of sugar in the blood leading to various health problems—have significantly increased in recent years among adolescents, with more and more teens now taking antidiabetic drugs. 4. Obesity may also affect brain function through metabolic syndrome (MeTS), which is a combination of risk factors typically associated  with obesity and includes high blood pressure, unhealthy cholesterol levels, and diabetes. 5. Children and adolescents whose parents are overweight have twin risk factors for becoming overweight themselves: the genes that their parents have passed along to them that may predispose them to be overweight and the environment that is created for them by overweight parents. 6. For instance, overweight parents are less likely to engage their children in vigorous physical activity. 7. Overweight parents are also more likely to be economically disadvantaged, so they purchase less expensive foods that are often high in calories and low in nutritional value. 8. Obesity is usually the product of both nature and nurture: Heredity is certainly important, but poor eating habits, inactivity, and parental behaviors contribute too. SLEEP 1. First, puberty ushers in changes in melatonin (a sleep-promoting hormone) production and circadian rhythms, which can shift the “natural” time for falling asleep later and later. Research shows that the level of melatonin rises later at night for teens than for children or adults, leading to later bedtimes. 2. The second change is the earlier start time of most high schools. 3. Teens who have had their sleep restricted display increased sleepiness in proportion to the number of nights that their sleep is reduced. 4. Other consequences for teens who sleep less at night are higher levels of depression, irritability, and lack of tolerance for frustration. 5. They may also have difficulty controlling their emotional responses, which leads to greater expression of aggression or anger. As with younger children, teens who do not get enough sleep have trouble concentrating in school, experience short-term memory problems, and may doze off in class. 4.14 CHANGING BRAIN The brain is responsive to experience and may be capable of neurogenesis, the process of generating new neurons, across the life span.  The study of blood volume in the brain and found that it was almost twice as high after the exercise program in the hippocampus, a part of the brain involved in learning and memory. This increased blood volume seems to be associated with production of new neurons. Other researchers have similarly found that physical exercise may increase neurogenesis, whereas other conditions such as stress or depression may decrease it. Neurogenesis, growth of new neurons, and neuroplasticity, or the brain’s ability to change, are two separate processes. Our brains might generate new neurons, but if we are unable to form new connections between neurons, we will struggle to reorganize or adapt to brain injury or damage. Fortunately, we know that neuroplasticity can occur across the life span and can be fostered by activity and enriched environmental experiences. In other words, your cultural experiences shape brain function and possibly also brain structure. Thus, the brain displays plasticity early in life and signs of neurogenesis and synaptogenesis throughout life. It can change in response to physical and mental exercise. It may be able to regenerate some functions following injury. Normal aging is associated with gradual and relatively mild degeneration of the nervous system, including some loss of neurons, diminished functioning of many remaining neurons, and potentially harmful changes in the tissues surrounding and supporting the neurons, such as the protective myelin covering. Brain weight and volume also decrease over the adult years, slowly from about age 30 to 50 and more swiftly after age 70. Decreases in gray matter, particularly in the frontal cortex, may be responsible for declines in attention and executive functioning, as well as difficulty generating and retrieving words. There are also reductions and changes in the brain’s white matter, which may account for the slower information-processing speeds and decreased episodic memory seen among many older adults. Other signs of aging include declines in the levels of important neurotransmitters and reduced blood flow to the brain, which may starve neurons of the oxygen and nutrients they need to function. We know that both degeneration and plasticity—both losses and gains— characterize the aging brain. In some people, degeneration may win and declines in intellectual performance will occur.  Neuroscientists have contributed to our understanding of this with research on three cognitive concepts: maintenance, reserve, and compensation. 1. MAINTENANCE: Neurocognitive maintenance refers to the regular upkeep of the brain, including those things we do across the lifespan to safeguard neurons and neural connections and, if it is damaged, to repair or heal our brain. 2. RESERVE: Neurocognitive reserve is our stockpile of neural resources that we save up over our lifetime. We then draw upon these resources to offset declines in cognitive performance as we age. Brain reserve, then, comes from the actual physical structure of the brain. Cognitive reserve refers to the “software,” or those mental skills that been built up over a lifetime through education, occupation, and so on. These things can also help preserve our cognitive functions as we age. 3. COMPENSATION: This is our ability to quickly 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 using standard operating principles. 4.15 THE CHANGING REPRODUCTIVE SYSTEM In young men, testosterone levels fluctuate across the day, with the highest levels in the morning and lower levels in the evening. For men in their 40s and older, testosterone levels are relatively flat across the day. Testicular volume, after remaining stable for much of adulthood, begins to decline after the age of 60 to the point that elderly men have lost nearly one-third of their testicular volume. The prostate gland is part of the male reproductive system, which secretes prostate fluid that mixes with sperm to produce semen. A very common change with age is enlargement of the prostate gland and a condition called benign prostatic hyperplasia BPH. In women, hormone levels shift drastically each month as they progress through their menstrual cycles. Most women report that these shifts are accompanied by symptoms such as bloating, moodiness, breast tenderness, and headaches during the days just before menstruation. Some women may experience more of these symptoms and at a more significant level to warrant classification of their symptoms as premenstrual syndrome (PMS)  Premenstrual dysphoric disorder (PDD). PDD differs from PMS in that it includes affective symptoms in addition to physical symptoms associated with the menstrual cycle, and it can be disabling—disrupting work and relationships. 4.15.1 FEMALE MENOPAUSE Sometime in midlife, between ages 45 and 54, women go through the process of menopause, which culminates in the ending of menstrual cycles. Levels of estrogen and other female hormones decline to the point where a woman is no longer ovulating, no longer menstruating, and no longer capable of conceiving a child. Researchers have discovered that menopause can be predicted by a hormone called anti-Müllerian hormone. Depending on the culture in which menopause is studied, somewhere between half and nearly all women experience some degree of hot flashes—sudden experiences of warmth and sweating, usually centered around the face and upper body, that occur at unpredictable times, last for a few seconds or minutes and are often followed by a cold shiver. For women who experience moderate to severe symptoms of menopause, their physician may prescribe hormone replacement therapy (HRT), taking estrogen and progestin to relieve physical symptoms of menopause, such as hot flashes and vaginal dryness. Women who have a history of menstrual problems (such as PMS) report more menopausal symptoms, both physical and psychological. Thus, some women may experience greater biological changes or be more sensitive to them. The effect of menopause is determined by the meaning it has for the woman, as influenced by her society’s prevailing views of menopause and by her own personal characteristics. 4.15.2 MALE ANDROPAUSE Andropause, also called age-associated hypogonadism, is characterized by slowly decreasing levels of testosterone and a variety of symptoms including low libido, fatigue and lack of energy, erection problems, memory problems, and loss of pubic hair.  As many as half of men over the age of 40 report some degree of erectile dysfunction—inability to achieve or sustain an erection for intercourse—despite having sufficient levels of testosterone. For many men, erectile dysfunction can be effectively treated with sildenafil, no doubt more familiar to you by the name Viagra. As a result, men experience fewer psychological effects. Frequency of sexual activity does decline as men age. However, this trend cannot be blamed entirely on decreased hormone levels because sexual activity often declines even when testosterone levels remain high. 4.16 HEALTH AND WELLNESS (ADULTS) Adults often struggle to maintain healthy lifestyles, which eventually catches up with many of them in the form of various chronic diseases including obesity, diabetes, hypertension, cancers, congestive heart failure, and more. Osteoarthritis is a common joint problem that results from gradual deterioration of the cartilage that cushions the bones from rubbing against one another. For some older adults, joint disease is deforming and painful and limits their activities. Another common affliction in old age is osteoporosis (meaning “porous bone”), a disease in which a serious loss of minerals leaves the bones fragile and easily fractured. It involves pain and can result in death if the victim falls and fractures a hip. Osteoporosis is a special problem for older women, who never had as much bone mass as men and whose bones tend to thin rapidly after menopause. 4.16.1 HEALTH DISPARITIES A health disparity exists when there is a difference in health status or health outcome that is associated with social, economic, and/or environmental disadvantage. Characteristics that have been found to influence group health include race or ethnicity, sex, sexual identity, age, disability, socioeconomic status, age, and geographic location. People in the lowest SES groups—that is, those who live in poverty—are more likely to experience poor health, higher rates of disability, and greater mortality rates.  Race and ethnicity have also been associated with health disparities. During the novel coronavirus 19 (COVID-19) pandemic that brought much of the world to a standstill in 2020, black people were disproportionately affected and suffered higher death rates from the virus than whites. In general, blacks are more likely to have underlying health conditions such as diabetes and hypertension that make viruses such as COVID-19 more deadly. It may not be race per se that creates health disparities but the socioeconomic and educational disparities that are associated with race. Children and adults in rural communities experience greater health challenges than those in urban settings, a disparity that has increased over the past several decades. Eliminating disparities in health requires a multipronged approach. Part of the solution may reside with providing better education on how lifestyle choices affect health and greater access to quality health care. They must also understand how to provide culturally competent care, or care that is attuned to a patient’s diversity and the cultural factors that might affect health and health care. Putting an end to health disparities related to race and ethnicity requires tackling discrimination and inequalities associated with belonging to a group that lacks power and in society. 4.17 HEALTHY AGING Overall, aging in the absence of disease had little effect on physical and psychological functioning. In particular, idea density, a measure of language-processing ability, assessed in early adulthood predicted mental functioning in later adulthood. The message to take away from such research is that both physical and mental activity, along with a positive attitude, can help slow the effects of aging on both the body and the brain. Muscles atrophy if they are not used, and the heart functions less well if a person leads a sedentary life. The brain also needs “mental exercise” to display plasticity and to continue to function effectively in old age.