Chapter 8 Notes

Infants, Children, and Adolescents (6th Edition)

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I. BODY GROWRTH A. Changes in Body Size and Proportions 1. On the average, 2 to 3 inches in height and about 5 pounds in weight are added each year. 2. The child gradually becomes thinner; girls retain somewhat more body fat, whereas boys are slightly more muscular. 3. Posture and balance improve, resulting in gains in motor coordination. 4. Individual differences in body size are even more apparent during early childhood than in infancy. 5. To determine if a child's atypical stature is a sign of a growth or health problem, the child's ethnic heritage must be considered. B. Skeletal Growth in which cartilage 1. Between ages 2 and 6, approximately 45 epiphyses, or new growth center hardens into bone, emerge in various parts of the skeleton. 2. X-rays permit doctors to estimate children's skeletal age, the best available measure of progress toward physical maturity. 3. By the end of the preschool years, children start to lose their primary teeth. 4. Childhood tooth decay remains high, especially among low-SES youngsters in the United States. C. Asynchronies in Physical Growth 1. Physical growth is an asynchronous process: different body systems have their own unique, carefully timed patterns of maturation. 2. The general growth curve is a curve that represents overall changes in body size-rapid growth during infancy, slower gains in early and middle childhood, and rapid growth once more during adolescence. 3. Exceptions to this trend are found in the development of the reproductive and lymph systems. II. BRAIN DEVELOPMENT A. Synaptic Growth and Pruning 1.Brain metabolism reaches a peak around 4 years of age. By this time, many cortical regions have overproduced synapses, which results in a high energy need. 2. The overabundance of synaptic connections is believed to play a role in the plasticity of the young brain. 3. Synaptic pruning occurs as neurons that are infrequently stimulated lose their connective fibers and the number of synapses is reduced. This process is adaptive. 4. A surprising feature of brain development is that rapid bursts of synaptic growth are accompanied by high rates of cell death in order to make room for the connective structures of active neurons. 5. Plasticity is reduced by ages 8 to 10, and energy consumption of most cortical regions declines to near-adult levels. B. Lateralization 1.The two hemispheres of the cortex develop at different rates. 2. The left hemisphere shows dramatic activity between 3 and 6 years and then levels off. 3. Activity in the right hemisphere increases slowly throughout early and middle childhood, showing a slight spurt between ages 8 and 10. 4. Differences in rate of development of the two hemispheres suggest that they are continuing to lateralize (specialize in functions).
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Chapter 8 Notes - I. BODY GROWRTH A. Changes in Body Size...

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