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Growth Changes Body in Body Proportions: Principles of Development Cephalocaudal Principle - from Latin, meaning "head to tail" Proximodistal Principle - from Latin, meaning "near to far" Changes in body proportion from the early prenatal period to adulthood During the first 2 years, the body grows more rapidly than at any time after birth. Research indicates that growth seems to occur in spurts, often after long periods of no growth. In infancy, girls are slightly shorter and lighter than boys. 1 Body fat increases after birth and peaks around 9 month of age. Toddlers become more slender, a trend that continues until middle childhood. Muscle tissue increases very slowly and doesn't peak until adolescence. The best way to estimate a child's physical maturity is to use skeletal age, a measure of the body's bone development. The epiphyses are the growth centers in the bones where new cartilage cells are produced and gradually harden. As growth continues, the epiphyses get thinner and disappear, and no more growth of the bone is possible. Long bone and epiphyses 2 An infant's first tooth usually appears between 4 to 6 months of age. By age 2, the child has 20 teeth. A child who gets her teeth early is likely to be advanced in physical maturity. At birth, the brain is nearer to its adult size than any other physical structure and it continues to develop at an astounding pace during infancy and toddlerhood. Neurons that are stimulated by input from the environment continue to establish new synapses. Those that are seldom stimulated soon die off. Myelinization is a process in which neural fibers are coated with an insulating fatty sheath (myelin) that improves the efficiency of message transfer. Neuron 3 The cerebral cortex is the largest structure of the human brain and accounts for 85% of its weight. It contains the greatest number of neurons and synapses, and it is the last of the brain structures to stop growing. Regions of the Cortex The order in which cortical regions develop corresponds to the order in which various capacities emerge in infancy and childhood One of the last regions of the cortex to develop and myelinate are the frontal lobes, which are responsible for thought and consciousness. Cerebral Cortex - Lobes Lateralization and Plasticity of the Cortex Lateralization is the specialization of function of the 2 hemispheres, or sides, of the cortex. It begins early in life and is molded by early experience. Brain plasticity is the ability of other parts of the brain to take over functions of a damaged part. During the first few years, the brain is more plastic than at any later time of life. 4 Heredity Nutrition Breast Milk Versus Formula Cow's Milk and Solid Foods Are Chubby Babies at Risk for Later Overweight and Obesity? Malnutrition Marasmus Kwashiorkor Emotional Well-Being Breast-feeding offers many nutritional and health advantages over bottle-feeding. Breast-fed babies in impoverished regions of the world are less likely to be malnourished and more likely to survive the first year of life. Some mothers cannot nurse because of physiological or medical reasons. Breast milk is easily digestible and, as a result, breast-fed become babies hungry more often than bottle-fed infants. Breast- and bottle-fed youngsters do not differ in psychological adjustment. Malnutrition Recent evidence indicates that 40 to 60% of the world's children don't get enough to eat. Among the 4 to 7% who are severely affected, malnutrition leads to 2 dietary diseases: Marasmus Kwashiorkor 5 Marasmus Kwashiorkor Children who survive these forms off malnutrition grow to be smaller in all body dimensions and their brains can be seriously affected. 6 Nonorganic failure to thrive is a growth disorder usually present by 18 months of age that is caused by lack of parental love If the disorder is not corrected in infancy, some children remain small and have lasting cognitive and emotional problems. The sequence of motor development Gross motor development refers to control over actions that help an infant move around in the environment, such as crawling, standing, and walking. Fine motor development involves smaller movements such as reaching and grasping. Although the sequence of motor development is fairly uniform across children, there are large individual differences in rate of motor progress. The sequence of motor development will follow the principles of development: cephalocaudal and proximodistal Motor Skills as Dynamic Systems Dynamic systems theory of motor development mastery of motor skills involves acquiring increasingly complex systems of action. Each new skill is a product of: Central nervous system Movement possibilities of the body The goal the child has in mind Environmental support When a skill is initially acquired, it's tentative and uncertain. The infant must practice and refine it so that the skill becomes smooth and accurate. Each skill is acquired by revising and combining earlier accomplishments into a more complex system that allows the child to reach a desired goal. 7 Fine Motor Development: Voluntary Reaching and Grasping Voluntary reaching plays a vital role in infant cognitive development. Motor skills start out as gross activities and move toward mastery of fine movements. Prereaching is the uncoordinated, primitive reaching movements of newborns. It eventually drops out around 7 weeks of age. Development of Voluntary Reaching and Grasping Voluntary reaching appears at about 3 months and gradually improves in accuracy. Early reaching is controlled by proprioception, our sense of movement and location in space that arises from stimuli within the body. The ulnar grasp is a clumsy grasp of young infants, in which the fingers close against the palm. The pincer grasp is a well-coordinated grasp that emerges at the end of the first year, involving the oppositional use of the forefinger and thumb. Trying to push infants beyond their current readiness to handle stimulation can undermine the development of important motor skills. Toilet training is best delayed until the end of the 2nd or beginning of the 3rd year. At this time, toddlers can correctly identify and respond to signals from a full bladder or rectum and wait until they get to the right place to permit these muscles to open, physiological developments essential for the child to cooperate with training. 8 ... View Full Document

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