Transcript chapter 5

Kathleen Stassen Berger
Part II
Chapter Five
The First Two Years: Infant and Toddlers
Body Changes
Brain Development
Senses and Motor Skills
Public Health Measures
Prepared by Madeleine Lacefield
Tattoon, M.A.
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“Adults don’t change
much in a year or two.
Their hair might grow
longer, grayer, or
thinner; they might be
a little fatter; or they
might learn something
new.
But if you saw friends
you hadn’t seem for
two years, you’d
recognize them
immediately.”
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• “By contrast, if you cared for
newborn 24 hours a day for a
month, went away for two years,
and then came back,you might
not recognized him or her,
because the baby would have
quadrupled in weight, grown
taller by more than a foot, and
sprouted a new head of hair.
• Behavior would have changed,
too. Not much crying, but some
laughter and fear—including of
you.”
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“A year or two is not much compared
with the 75 or so years of the
average life span. However, in two
years newborns reach half their adult
height, talk in sentences, and
express almost every emotion—not
just joy and fear but also love,
jealousy, and shame.”
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Biosocial Development
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Body Changes
– In infancy
• growth is fast
• neglect can be severe
• gain needs to be monitored
• health check-up need to include
– height, weight and head circumference
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Body Size
• rapid growth
• double their birth weight by the 4th month
and triple by the 1st birthday
• physical growth slows in the 2nd year
• by 24 months weight is about 30 lbs, height
about 32”-36”
– these numbers are “norms”
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Body Size
• “norms”
– an average or standard for a particular population
• “particular population”
– a representative sample of North American infants
• “percentiles”
– a number that is midway between 0 and 100, with ½ the
children above it and ½ below it
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Body Size
• Weight increase in the early months is fat,
providing insulation for warmth and
nourishment
• Nourishment keeps the brain growing, if
teething or illness interfere with eating
• When nutrition is temporarily inadequate, the
body stops growing but not the brain
– this is known as a phenomenon called
“head-sparing”
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Sleep
• Infants sleep about 17 hours or more a day
• Regular and ample sleep correlates with normal brain
maturation, learning, emotional regulation, and
psychological adjustment in school and within the family
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Sleep
• Over the first month the amount of time spent in
each type or stage of sleep changes
• Newborns dream a lot, or at least they have a high
proportion of “REM sleep”
– REM sleep
• rapid eye movement sleep is a stage of sleep
characterized by flickering eyes behind closed lids,
dreaming, and rapid brain waves
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Sleep
• Sleep Patterns can be…
– affected by birth order
• first born typically receive more attention
– diet
• parents might respond to predawn cries with food,
and/or play (babies learn to wake up night after
night)
– child-rearing practices
• “Where should infants sleep?”
– co-sleeping or bed-sharing
– brain maturation
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Brain Development
– the newborn’s skull is disproportionately large
– large enough to hold the brain, which at birth is 25%
of the adult brain
– the neonate’s body is typically 5% of the adult weight
– by age 2 the brain is almost 75% of the adult brain
weight
– the child’s total body weight is only about 20% of its
adult weight
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Basic Brain Structures
• Neurons are one of the billions of nerve
cells in the central nervous system,
especially the brain.
• Located in the brain or in the brain stem
–the region that controls automatic
responses, I.e., heartbeat, breathing,
temperature, and arousal
• 70% of the neurons are in the cortex
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Basic Brain Structures
• The cortex is crucial for humans…
– 80% of the human brain materials in the cortex
– in other mammals the cortex is proportionally
smaller, and non-mammals have no cortex
– most thinking, feeling, and sensing take place
in the cortex, although other parts of the brain
join in.
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Basic Brain Structures
• Areas of the cortex specialize
in particular functions:
– visual
– auditory
– an area dedicated to the
sense of touch for each
body part
– regional specialization
within the cortex occurs
not only for motor skills
and senses but also for
aspects of cognition
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Basic Brain Structures
• Between brain areas, neurons are
connected to other neurons by intricate
networks of nerve fibers called axons and
dendrites
– a neuron has a single axon and numerous
dendrites, which spread out like the branches of
a tree
– axons and neurons meet the dendrites of other
neurons at intersections called synapses which
are critical communication links within the brain
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Basic Brain Structures
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Basic Brain Structures
• Transient Exuberance and Pruning
– The fivefold increase in dendrites in the cortex
occurs in the 24 months after birth, with about
100 trillion synapses being present at age 2
– The expanded growth is followed by pruning in
which unused neurons and misconnected
dendrites atrophy and die
– Synapses, dendrites, and even neurons continue
to form and die throughout life, though more
rapidly in infancy than at any other time
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Basic Brain Structures
• Experience Shapes the Brain
– brain structure and growth depends on genes
and experiences
– some dendrites wither away because they are
underused; no experiences have caused
them to send a message to the axons of other
neurons.
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Basic Brain Structures
• Stress and the Brain
– the role of experience in brain
development begins when the brain
produces cortisol and other hormones in
response to stress, which happen
throughout life
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Basic Brain Structures
• Experience-expectant refers to brain
functions that require certain basic common
experiences, which an infant can be
expected to have in order to develop
normally
• Experience-dependent refers to brain
functions that depend on particular, variable
experience and that therefore may or may
not develop in a particular infant
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Basic Brain Structures
– Basic, common experiences must
happen for normal brain maturation to
occur
– in contrast, dependent experiences might
happen. Because of them, one brain
differs from another
– experience varies; language babies hear
or how their mothers reacts to frustration
– all people are similar, but each person is
unique, because of early experiences
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Basic Brain Structures
• The last part of the brain to mature is
the prefrontal cortex
– The area for anticipation, planning, and
impulse control
– Virtually inactive in early infancy
– Gradually becomes more efficient over
the years of childhood and adolescence
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Basic Brain Structures
• Implications for Caregivers
– Early brain growth is rapid and reflects
experience…
• caressing a newborn,
• talking to a preverbal infant
• showing affection
– …are essential to develop that person’s full
potential
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Basic Brain Structures
The human brain is designed to grow and
adapt
– some plasticity is retained throughout life
– the brain protects itself from overstimulation
– babies adjust to understimulation
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Basic Brain Structures
• THINK LIKE A SCIENTIST
– Plasticity and Orphans
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Senses and Motor Skills
• Sensorimotor stage
–cognition develops from
the senses and motor
skills
–depends on sensory
experiences and early
movement
• within hours of birth vital
organs are functioning,
assessing basic senses
and motor responses
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Sensation and Perception
– All the senses function at birth
• open eyes, sensitive ears, and responsive
noses, tongues, and skin
– Very young babies attend to everything
• Infants don’t focus on anything in particular
• To about age one taste is the primary way
humans learn about objects
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Sensation and Perception
– Sensation is the response of a sensory
system…
• eyes, ears, skin, tongue, nose
– …when it detects a stimulus
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Sensation and Perception
– Perception is the mental processing of
sensory information…
• the brain notices and processes a
sensation…
– when the brain interprets a sensation…
– Infant’s brains are attuned to experiences
that are repeated, striving to make sense
of them
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Senses and Motor Skills
– Hearing
• Hearing is acute at birth
• Certain sounds trigger reflexes
• Sudden noises startle newborns
• Rhythmic sounds soothe them and put
them to sleep
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Senses and Motor Skills
– Seeing
• At birth vision is the least mature
• The infant eyes are sensitive to bright light
even though the eyes open in midpregnancy
• Newborns are “legally blind” they can only
see objects 4” – 30” away
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Senses and Motor Skills
– Seeing
• At two months infants look more intensely
at faces and often smile
• At three months infants look more closely
at the eyes and mouth
– The ability to focus the two eyes in a
coordinated manner in order to see one
image is known as binocular vision
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Senses and Motor Skills
– Tasting, Smelling and Touching
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Senses and Motor Skills
– Tasting, Smelling and Touching
• At birth the senses of taste, smell and touch
function and rapidly adapt to the social
world
• As infants learn their caregiver’s smell and
touch (handling) they relax and cuddle
• Over time infants become responsive to
whose touch it is and what it communicates
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Senses and Motor Skills
– Early sensation seems to have two goals:
• Social interaction
–To respond to familiar caregivers
• Comfort
–To be soothed amid the disturbances of
infant life
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Senses and Motor Skills
– Motor Skill is the learned ability to move
some part of the body, from a large leap
to a flicker of the eyelid.
(
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Senses and Motor Skills
– Newborns have many reflexes, some of
which disappear with maturation (a
reflex is an involuntary response to a
particular stimulus
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Senses and Motor Skills
– Reflexes
• three sets are critical for survival
–that maintain oxygen supply
–that maintain constant body temperature
–that manage feeding
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Senses and Motor Skills
– Gross Motor Skills are physical abilities involving
large body movements (gross meaning “big”)
• walking
• jumping
– Walking progress
• from reflexive,
• to hesitant
• to adult-supported stepping
• to a smooth coordinated gait
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Senses and Motor Skills
– Gross Motor Skills
• Three factors combine to allow toddlers to
walk
– muscle strength
– brain maturation within the motor cortex
– practices
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Senses and Motor Skills
– Fine Motor Skills are physical abilities
involving small body movements,
especially of the hands and fingers (fine in
this text means “small”)
• drawing
• picking up a coin
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Senses and Motor Skills
• Ethnic Variation
– healthy infants develop skills in the same
sequence
– they vary in the age at which they acquire
them
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Senses and Motor Skills
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Senses and Motor Skills
– Genes are only a small part of most ethnic
differences
– Cultural patterns of child rearing can affect
sensation, perception, and motor skills
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Public Health Measures
– 8 billion children were born between 1950
– 2005
– 2 billion died before age 5
• Deaths could be twice this if not for:
– Child care
– Preventive care – immunization
– Clean water
– Adequate nutrition
– Medial treatment, etc.
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Public Health Measures
• Immunization is a process that stimulates the
body’s immune system to defend against attack
by
a
particular
contagious
disease
(immunization acquired either naturally, by
having the disease or though vaccination)
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Public Health Measures
• Sudden Infant Death Syndrome (SIDS)
– die unexpectedly in their sleep
– No apparent cause of death
– 1990 in the U.S., 5000 babies died of
SIDS, 1 in 800
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ISSUES AND APPLICATONS
Back to Sleep
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Nutrition
• Breast is Best
– Good nutrition starts with mother’s milk
• Colostrum, a thick, high-calorie fluid
secreted by the woman’s breast at the birth
of a child.
• About 3 days later the breast begins to
produce milk
• Breast fed babies are less likely to get sick
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Nutrition
• Malnutrition
– protein-calorie malnutrition is a condition in
which a person does not consume
sufficient food of any kind
– the deprivation can result in several
illnesses, severe weight loss, and
sometimes death
– to measure a child’s nutritional status,
compare weight and height with the
"norms"
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