Chapter 2 Infancy Module 2 1 Physical Development in Infancy 1 2 3 2009 Looking Ahead z How do the human body and nervous system develop z Does the environment affect the pattern of development z What developmental tasks must infants accomplish in this period z What is the role of nutrition in physical development z What sensory capabilities do infants possess 2 3 2009 2 1 GROWTH AND STABILITY 3 2 3 2009 Physical Growth z 2 3 2009 Rapid growth during first two years 4 2 Head to body size ratio changes dramatically 5 2 3 2009 Nervous System and Brain z z 2 3 2009 Nervous system comprises the brain and the nerves that extend throughout the body Neurons are the basic cells of the nervous system 6 3 7 2 3 2009 Cellular Basis of Brain Development Migration of cells z Formation and growth of axons z Formation of dendrites z Formation of synaptic connections z Myelination z 2 3 2009 8 4 How brains grow z Birth 100 200 billion neurons Relatively few neuron to neuron connections z During first two years Billions of new connections established and become more complex 9 2 3 2009 Use it or lose it Synaptic pruning z Unused neurons are eliminated z Allows established neurons to build more elaborate communication networks with other neurons z Development of nervous system proceeds most effectively through loss of cells But also note the importance of myelin 2 3 2009 10 5 Form and Function Brain Growth z Neurons reposition themselves with growth becoming arranged by function Cerebral cortex Subcortical levels 2 3 2009 11 Environmental Influences on Brain Development z Plasticity z Sensitive period 2 3 2009 12 6 Don t shake the baby z Shaken Baby Syndrome Brain sensitive to injury Shaking can lead to brain rotation within skull z Blood vessels tear severe medical problems long term disabilities and sometimes death 2 3 2009 13 MOTOR DEVELOPMENT 2 3 2009 14 7 Reflexes Inborn Physical Skills z Reflexes learned organized involuntary responses that occur automatically in presence of certain stimuli 15 2 3 2009 Major Reflexes in Full Term Neonates Survival 2 3 2009 Breathing permanent Eye blink permanent Pupillary permanent Rooting Disappears over first few weeks replaced by voluntary head turning Sucking permanent Swallowing permanent 16 8 17 2 3 2009 Major Reflexes in Full Term Neonates Primitive Bibinski plantar 8 month 1 year Palmar grasping Swimming 3 4 months replaced by voluntary grasping Arms and arching stop at 4 6 months 4 6 months Stepping First 8 weeks Moro 2 3 2009 18 9 2 3 2009 19 2 3 2009 20 10 21 2 3 2009 Motor Development in Infancy Milestones of Normal Motor Development 2 3 2009 22 11 2 3 2009 23 Motor Development in Infancy Fine Motor Skills 2 3 2009 24 12 Developmental Norms Comparing Individual to Group Norms Represent the average performance of a large sample of children of a given age Permit comparisons between a particular child s performance on a particular behavior and the average performance of the children in the norm sample Must be interpreted with caution z Brazelton Neonatal Behavior Assessment Scale NBAS 25 2 3 2009 Nutrition in Infancy Fueling Motor Development z Without proper nutrition infants cannot reach physical potential and may suffer cognitive and social consequences z Infants differ in growth rates body composition metabolism and activity levels 2 3 2009 26 13 So what is a healthy caloric allotment for infants About 50 calories per day for each pound of weight z Most infants regulate their caloric intake quite effectively on their own z If are allowed consume as much they seem to want and not pressured to eat more they will be healthy z 27 2 3 2009 Malnutrition Children living in many developing countries z Slower growth rate z Chronically malnourished during infancy later lower IQ score z 2 3 2009 28 14 Learning about the World Sensation z Perception z 29 2 3 2009 Visual Perception Seeing the World Newborn s distance vision ranges from 20 200 to 20 600 z By 6 months average infant s vision is already 20 20 z Other visual abilities grow rapidly z Binocular vision Depth perception 2 3 2009 30 15
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