Ch_4_Physical_development_in_infancy - Physical Development...

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Physical Development in Infancy and Toddlerhood Body Growth Changes in Body Size and Muscle-Fat Makeup o Babies increase in height 50% in the first year. Birth weight doubles in 5 mo., triples by 1 year. This growth comes in spurts, preceded by hunger and irritability. Adding baby fat helps baby maintain temperature. During the second year, babies slim down a bit. Individual and group differences o Girls are generally shorter and lighter and more fat to muscle than boys, even in infancy (dramatically differs in adolescence). Ethnic background makes a difference, too, as Asians tend to be smaller and shorter than Caucasians. African-Americans tend to be larger. The best way to estimate physical maturity is skeletal age- a measure of bone development seen through measuring the long bones to see how much cartilage has ossified. Girls’ rate of growth is faster than boys, as well as resistance to environmental impacts. Girls have lower mortality rates at every age. Boys have more developmental problems such as stuttering or learning disabilities. Changes in body proportions - parts of the body grow at different rates. o Cephalocaudal trend – growth moves from top down. Head develops faster than trunk and legs. o Proximodistal trend - growth moves from center of body outward. Brain development Neural development - brain has 100 – 200 billions neurons , although they aren’t well connected at birth. Neurons connect over tiny gaps, synapses , through a chemical communication of neurotransmitters. o Synaptic pruning is the process of some neurons returning to an uncommitted state, unconnected to others due to lack of stimulation. Some tracks get very well connected due to repeated stimulation, and to make room for these paths, unused neurons deteriorate. o Glial cells secrete myelin , which is a fatty coating that allows some neurons to send the neural message much faster. Not all neurons are myelinated. Glial cells are the support cells for the neural system. When a part of the brain myelinates, usually a new ability erupts. (In the early teen years, the frontal lobes myelinate, allowing for abstract, complex thought.) Cerebral Cortex surrounds the brain, like the icing on a cake. It makes up 85% of brain weight and allows humans complex thought and language. Lateralization of the 2 sides, hemispheres of the brain allows fro more abilities than if each side had to do all activities. Each side controls the opposite side of the body. Lefties have less specialization of the brain, & many are ambidexterous. Brain specialization is evident at birth. Speech sounds trigger more brain wave activity on the left side, music and other stimuli trigger more activity in the right side of the brain. Also babies display a preference for a hand early on, possibly due to how the baby lies in the womb. 10% of people are left handed. o
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This note was uploaded on 11/07/2010 for the course PSY 9 taught by Professor Mtso during the Fall '10 term at Riverside Community College.

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Ch_4_Physical_development_in_infancy - Physical Development...

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