Growth and Stability

  • Physical Growth: The Rapid Advances of Infancy
    • 4 Principles of Growth
      • Cephalocaudal­ growth follows a pattern that begins with the head and upper body parts and then proceeds down to the rest of the body
      • Proximodistal­ development proceeds from the center of the body outward
      • Hierarchical Integration­ simple skills typically develop separately and independently but are later integrated into more complex skills
      • Independence System­ different body systems grow at different rates
        • Growth in one system does not mean that there is growth in another area
        • Ex: woman grows breasts but doesn’t grow in height
      • The Nervous System and Brain: The Foundations of Development
        • Nervous System­ brain/nerves that extend thru the body Neurons­ basic cell of nervous system a. Dendrites­ receive messages
          • Cell body­ aka soma­
          • Axon­ transmits messages
          • Synaptic Cleft­ tiny space that separates neurons so they do not directly touch each other; where the axon terminal of one neuron nearly touches the dendrite or the cell body of another neuron

Synapse­ the gap at the connection between neurons, through which neurons chemically communicate with one another

    • Synaptic Pruning­ severing of unnecessary and unused connections; if a baby’s experiences do not stimulate certain nerve connections these are eliminated
    • Myelin Sheath­ a fatty substance that helps insulate neurons and speeds the transmission of nerve impulses

Nodes of Ranvier­ if an axon in unmyelinated/uninsulated, the action potential at each point in the axon causes a new action potential at the next point; capable of generating electrical activity

  • Neuron specialization­ the neurons are also starting to differentiate into different areas of the brain
  • Cerebral cortex­ the upper layer of the brain responsible for higher­order processes such as thinking and reasoning; become more developed and interconnected over time
  • Subcortical levels­ located below the cerebral cortex; regulate such fundamental activities as breathing and heart rate are fully developed at birth
  • Shaken Baby syndrome aka Abusive head trauma/ inflicted traumatic brain injury­ is a form of head trauma

How these injuries happen:

  • Results from injuries caused by someone vigorously shaking a child; major victims are infants younger than 1yr.
  • Normal interaction with a child, like bouncing a baby on a knee, will NOT cause these injuries

Environmental Influences on Brain Development

Plasticity­ the degree to which a developing structure or behavior is modifiable due to experience

  • Greatest during the first several years of life
  • b/c many areas of the brain aren’t specialized yet, if one part is damaged other areas can take over
  • Downside? A particularly restricted or impoverished environment can have a negative effect on brain and cognitive development

Infant Sleep

Newborns: 16­17hrs a day

  • Low= 10hrs; high= 21hrs
  1. REM sleep­ the period of sleep that is found in older children and adults and is associated with dreaming; also called paradoxical sleep
  2. SIDS (Sudden Infant Death Syndrome)­ a condition that occurs when infants stop breathing, usually during the night, and suddenly die without an apparent cause
  • American Academy of Pediatrics recommends that infants be placed on their back to reduce the risk
  • Decreased from 70% to 20% of US infants

Motor Development

  • Reflexes: Our Inborn Physical Skills

Reflexes­ the unlearned, organized, voluntary responses that occur automatically in the presence of certain stimuli

  • Presence and strength of a reflex is important sign of nervous system development and function.
  • Infant reflexes disappear as children grow older
    • Stepping Reflex: 2 months; movement of legs when held upright with feet touching the floor; prepares infants for independent locomotion
    • Swimming reflex: 4­6 months; infant’s tendency to paddle and kick in a sort of swimming motion when lying face down in a body of water; avoidance of danger
    • Moro reflex: 6 months; activated when support for the neck and head is suddenly removed; similar to primates’ protection from falling
    • Babinski reflex: 8­12 months; infant fans out its toes in response to a stroke on the outside of the foot; unknown
    • Startle reflex: remains in a different form; in response to a sudden noise, flings out its arms, arches its back and spreads its fingers; protection
    • Eye­blink reflex: remains; rapid shutting and opening of eye on exposure to direct light; protection of eye from direct light
    • Gag reflex: remains; an infant’s reflex to clear its throat; prevents choking
    • Motor Development in Infancy: Landmarks of Physical Achievement
    • Gross and Fine Motor Skills

Gross motor skills

  • Placed on stomach an infant will wiggle arms and legs and may lift their heads
  • Crawling: 8­10 months; mile stone
  • Walking: 9 months; supported by furniture Fine motor skills
  • 3 months; shows ability to coordinate movement of limbs
  • 11 months; picking objects up
    • Nutrition in Infancy
      • Malnutrition­ the condition of having an improper amount and balance of nutrients
      • Undernutrition­ some deficiency in diet
        • Marasmus­
        • Kwashiorkor­
        • Nonorganic failure to thrive­ disorder in which infants stop growing due to a lack of stimulation and attention as the result of inadequate parenting
        • Obesity­ a weight greater than 20% above the average for a given height
      • Bottle or Breast

Development of the Senses

Sensation­ the physical stimulation of the sense organs

Perception­ the sorting out, interpretation, analysis, and integration of stimuli involving the sense organs and brain

  • Visual perception­ newborns do not see that well; vision clears up around 3 months
    • Visual cliff­ involves an apparent, but not actual drop from ones surface to another.