Human Growth and Development Chapter Five

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Human Growth and DevelopmentChapter Five

• First Two Years
• Biosocial Development

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• Most notable time for physical changes
• in each of the first 12 months they grow an inch
• birth weight usually doubles by 4 months and
  triples by end of first year
• Consequences of neglect severe
• head-sparingbiological protection of the brain
  when malnutrition temporarily affects body growth

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Sleep

• Newborns sleep about 17 hours per day
• needed for rapid growth
• REM sleeprapid eye movement sleepdeclines
• quiet sleep increases at about 3 months
• too immature to sleep through the night
• Infants sleep patterns influenced by brain waves
  and parents caregiving practices

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Early Brain Development

• Most critical biosocial aspect of growth
• newborns skull disproportionately large
• at birth, 25 of adult brain weight
• by age 2, 75 of adult brain weight

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Areas of the cortex
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Basic Brain Structures

• Neuronslong thin nerve cells that make up
  nervous system
• created before birth
• 70 in cortex (brains outer layer)
• Axonsnerve fibers that extend from neurons that
  send impulses
• Dendritesnerve fibers extending from neurons
  that receive impulses

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• Each neuron has a single axon (nerve fiber) that
  extends from it and meets the dendrites of other
  neurons at intersections called synapses
• axons and dendrites dont actually touch at
  synapses
• electrical impulses trigger brain chemicals
  called neurotransmitters, which carry information
  from axon of sending neuron across synaptic gap
  to dendrites of receiving neuron
• synapses are critical communication links with
  the brain

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• At birth more than 100 million neurons are
  present
• Phenomenal growth is referred to as transient
  exuberancefivefold increase in dendrites in
  first 2 years
• As many as 15,000 connections may be made per
  neuron

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Experience Enhances the Brain

• Specifics of brain structure and growth depend
  partly on experience
• underused neurons are inactivated, or pruned

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• Reactions to Stress
• experiencing stress may cause overproduction of
  stress hormone
• developing brain can lose capacity to react
  normally to stress
• normal neuron connections may have been pruned
  for rapid response to repeated stress

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• Human brains are designed for expected
  experiences
• the brain expects certain experiences at certain
  ages
• these experiences are critical if connections are
  to form if connections are not formed,
  plasticity may allow new connections and pathways
  as experiences continue

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Sensation and Perception

• All senses function at birth
• sensationthe response of sensory system when it
  detects stimulus
• begins with outer organnose, eyes, etc.
• perceptionmental procession of sensory
  information when brain interprets sensation
• begins in the brain and requires experience
• cognitionthinking about what was perceived

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Listening

• Begins prenatally and is acute at birth
• Certain sounds trigger newborns reflexes
• Newborns particularly attentive to human voice

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Looking

• Vision is the least mature sense at birth
• Visual experience combined with visual cortex
  maturation improves vision
• Binocular visionability to focus two eyes in a
  coordinated manner to see single image begins at
  14 weeks

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Tasting, Smelling, and Touching

• tastefunctions at birth calmed by sugar,
  sensitive to sour
• touchcomforted by human touch feel pain
• smellcan distinguish between odors and have
  preferences
• Early sensation is organized for social
  interaction and comfort

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Motor Skills

• Reflexes for survival are categorized
• maintain oxygen supply (breathing, hiccups,
  sneezes, thrashing to remove cover on face)
• maintain body temperature (crying, shiver, curl
  up kicking away covers)
• manage feeding (crying when hungry, rooting,
  sucking, swallowing, spitting up if too much)

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Gross Motor Skills

• Involve large muscles and body movements
• crawling, creeping, walking

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Fine Motor Skills

• Small, finely tuned movements, especially of
  hands and fingers, including
• successful grabbing
• fingering, pointing, and holding
• grasping a moving object
• transferring objects from hand to hand
• adjusting reach

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Age Norms (in months) for Gross Motor Skills
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• Age at which motor skills acquired varies greatly
  because of ethnicity
• inherited factorsgenetic differences
• patterns of infant care
• individual rate of physical maturation

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Public Health Measures

• Immunizationprocess that stimulates bodys
  immune system to defend against attack by a
  particular contagious disease

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Sudden Infant Death Syndrome (SIDS)

• Risk factors?
• laying baby on stomach to sleep
• secondhand smoke
• low birthweight
• formula feeding rather than breast feeding

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NutritionBreast is Best

• Breast Milk
• begins with colostrum, high-calorie nourishment
  before milk lets down
• easily digestible
• has antibodies and antibacterial properties
• better for babys health
• less SIDS
• Bottle Feeding babies more likely to have
  allergies
• better option if mother is HIV-positive or using
  drugs
• Feeding on Demand