550 likes | 611 Views
Chapter Four. PHYSICAL DEVELOPMENT. The Brain and Nervous System. Major Structures of the Brain. The Brain and Nervous System. Synaptic Development. Synaptic Development. Both processes heavily dependent on experiences Follows “ use it or lose it ” dictum
E N D
Chapter Four PHYSICAL DEVELOPMENT
Synaptic Development Both processes heavily dependent on experiences • Follows “use it or lose it” dictum • Early flexibility allows children to adapt to environment better • Programmed plasticity is in its height in infancy
Myelinization • Formation of myelin sheath • Cephalocaudal and proximodistal patterns • Developmental path • Functions
Lateralization • Corpus callosum growth and maturation • Left and Right Brain Dominance • Lateralization • Sign language learning
Lateralization Spatial Perception: Ability to identify and act on relationships of objects in space • Relative right-left orientation
Lateralization Spatial cognition: ability to infer rules from and make predictions about the movements of objects in space • Gender differences • Environmental influences
Lateralization Handedness • Prevalence • Incidences • Appearance
Bones, Muscles, and Motor Skills • Patterns of Change in Size and Shape: Height and Weight Gains
Bones, Muscles and Motor Skills Bones • Fontanels • Skull soft spots that fuse as bones grow • Filled in by 12-18 months • Ossification • The process of bone hardening • Occurs steadily from birth to puberty
Bones, Muscles, and Motor Skills Muscles and Fat • Virtually all muscle fibers are present at birth • Developmental changes • Gender differences • Strength
Bones, Muscles, and Motor Skills Using the Body • Stamina • Changes are linked to growth of the heart and lungs, especially during puberty • Before puberty, boys and girls are similar in physical strength, speed, and stamina • After puberty, boys are ahead in all three • Motor Development • Gross motor skills develop earlier than fine motor skills • Fine motor skills develop rapidly in the elementary school years
The Endocrine and Reproductive Systems Hormones • Pituitary gland • Thyroid and pituitary growth hormones • Adrenal androgen • Gonadatrophic hormones
Sequence of Changes in Girls and Boys Girls • Development of pubic hair and breasts • Growth spurt follows • Menarche follows 2 years after other visible signs • Occurs between 12 ½ and 13 ½ • Follows a secular trend—caused by changes in diet and lifestyle • Possible to conceive shortly after menarche, but irregularity is the norm
Sequence of Changes in Girls and Boys Boys • Growth spurts come later in the stages than in girls • Development of beard and lowering of voice comes late in the stages • Boys can attain fertility as early as age 12 or as late as age 16
Questions to Ponder • Remembering your own adolescence, • Were you an early, normal, or late bloomer? • How did your body changes affect your mental image and your behaviors? • Does the research on sexual behavior match your experiences and that of your friends? Why or why not? ? ? ?
Sexual Behavior in Adolescence Prevalence of Sexual Behavior • Gender differences • Multiple partners • High school sexual experience across ethnic groups
Sexual Experience among High School Students in the United States
Explaining Adolescent Sexual Behavior • Social factors are better predictors of sexual activity than hormones
Teenage Pregnancy • Higher in United States than in any other Western industrialized country • Ethnic differences • Older adolescent births are more common
Homosexuality Pattern of realization of homosexuality • May begin in middle childhood • Homosexual fantasies begin in teen years • Full awareness and acceptance appear to take place in early adulthood • Slow process may lead to isolation and peer rejection
Health and Wellness Health in Childhood • Health Care Needs • Illnesses and Accidents • Age and Gender Differences
Poverty and Health • Poor children miss more days of school • The cycle of poverty
Health and Wellness Adolescent Health • Health Care Issues • May develop physical symptoms to parental or peer rejection • Most likely to need medical care for accidents
Health and Wellness Adolescent Health • Sensation-Seeking • Desire to experience high levels of arousal • Increased rates of accidents • Risky behaviors help teenagers gain peer acceptance and establish autonomy
Health and Wellness Alcohol and Drug Use • More common in sensation-seekers • Peers who drink or use drugs seek out others who do the same Parentalperceptions influence abstinence from drugs and alcohol • Parents need to take a proactive approach to prevention