Transcript Document 7306543

THE PHYSICAL SELF:
DEVELOPMENT OF THE
BRAIN, THE BODY, &
MOTOR SKILLS
Physical Development
• In the 1st few months, children grow nearly an ounce each day
and an inch each month
• First two years marked by rapid growth.
– Doubling their birth weight by 4 to 6 months.
– Tripling their birth weight by the end of their 1st yr. of life (21 pounds).
• Growth is rapid but irratic.
– Children may stagnate in growth for days or even weeks before
experiencing a growth spurt (over centimeter in a day).
– By age 2, toddlers already have half their eventual adult height and have
quadrupled their birth weight to some 30 pounds
– From age 2 until puberty, children gain about 2 to 3 inches in height and 6
to 7 pounds in weight each year
Changes in Body Proportions
• A newborns head is 70% of its eventual adult size and
represents ¼ of the infants length
• Cephalocaudal Development
– Trunk grows fastest during the 1st year
– At 1yr, the head accounts for 20% of total body length
• Proximodistal Development
– During prenatal development, chest and internal organs form 1st
followed by arms & legs and then hands & feet
– Throughout infancy and childhood, arms & legs continue to
grow faster than hands and feet
Skeletal Development
•
Skeletal structure starts as soft cartilage during prenatal and gradually hardens
(Ossification).
– Discuss Epiphysis (growth centers where new cartilage is formed.
– This is why infants cannot initially set up or balance themselves
•
Neonates skull consists of several soft bones that can be compressed to allow for the
passing thru cervix and birth canal
– Skull bones are separated by 6 soft spots called fontanelles
– By age 2, these soft spots solidify leaving smaller seams (sutures) which allow the skull to
expand as the brain grows larger
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Bones in ankle/feet and wrist/hand increases as child matures
Skeletal age is often determined thru x-ray of hands/feet to examine bone density and
interconnections
– Girls mature faster than boys (This may explain why girls tend to be healthier and more
resistant to illnesses)
– African-American children develop faster than Caucasian children --At birth, girls are 4 to 6
wks ahead of boys regarding skeletal maturity; by age 12, the maturity gap widens 2 full
years
•
Bones in skeletal system grow and harden at different rates
– Skull and hands mature first; leg bones reach mature development in late teens
– In general, mature skeletal development occur by age 18
Skeletal Development Cont.
• While children grow and develop at
different rates, the best predictor of maturity
is skeletal development.
Presence of Teeth
• In general, infants get their first tooth around 6 months
to a year. However,
– There are differences as a function of gender and ethnicity.
• Because girls mature faster than boys and African-Americans mature
faster than Caucasian infants. Both groups tend to get their first tooth
earlier
– In some cases, children are born with their first tooth
– By age 2, children generally have all 20 of their primary teeth
Muscular Development
• Neonates are born with all the muscle fibers they will ever need
– At birth, muscle tissue is 35% water (later replaced by nutrients and salts);
accounting for 18 to 24% of the babies weight
– Muscle development proceeds in Cephalocaudal and Proximodistal manner.
Muscles in head and neck maturing faster than muscles in trunk and limbs
– With growth spurts in muscles, boys make significant gains in strength and
size
– Variations in physical growth depends on genes and cultural practices
• People from Asia, South America, & Africa tend to be smaller than North
America, North Europe, and Australia
Development of the Brain
• Brain grows from 25% of its adult weight at birth to
75% of adult weight by age 2.
• The last 3 prenatal months and the first 2 years after
birth are termed the period of the brain growth spurt
(more than half of brains weight added at this time).
– The brain function consists of a trillion specialized cells that
transmit exectrical/chemical signals.
• Synapses
• Neurons—100 to 200 billion cells produced in neural tube during 2nd
trimester
• Glial—2nd type of nerve cell that provide nourishment and encasement
to neurons
Cell Differentation and Synaptogenesis
• Neurons assume specialized functions as they migrate to certain areas of the
brain
• Synaptogenesis
– As neurons become more specialized, the interconnections forms to provide for
reasoning and problem-solving
• Through appropriate stimulation, children develop appropriate synapses.
Neurons that fail to interconnect (about half) fail to survive—This is the
pruning process
• An infant’s brain exhibits high plasticity (capability of change and adaptation).
As we get older, brain cells become more rigid and inflexible
• Much research seems to suggest that early experiences (both in humans and
animals) play a vital role toward brain formation.
– Maximal development for certain talents are related to sensitive periods where
environmental stimulation is necessary for brain formation
Cerebral Lateralization
• The brain divides into left and right hemispheres.
– Left side/brain controls right side/body and contains centers for speech,
hearing, verbal memory, decision making, language, and expression of
positive emotions
– Right side/brain control left side of body and contains centers for
processing visual-spatial information, nonlinguistic sounds such as music,
touch sensations, and expression of negative emotions
• 90% of adults are left hemisphere dominant
• Brain lateralization was initially thought to occur by end of
puberty.
– Recent research identifies prenatal lateralization
– Brain lateralization/plasticity remain quite high for the first 3 years of life.
Gradually diminishes with age.
Motor Development
• By the end of the first month, most babies can
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Lift their chins while lying flat on stomach
Lift their chests
Reach for objects
Roll over and sit up with some support.
• Motor develop has been used as a predictor for long-term developmental
outcomes in the past
– More recent research suggest that variations in motor gains do not significantly
predict long-term developmental outcomes
– (See Table 5.1 on page 152 for sequence of motor development).
Explanations for Sequencing and Early Timing of Early
Motor Development
• Maturational viewpoint:
Biological/genetic blueprint determines the
sequence of nervous and muscular system development (Downward/Outward).
– Cross cultural studies have indicated consistent developmental patterns.
– Twin study in which one child allowed to practice motor skills while the other not
allowed to practice. Upon testing, no long-term significant adjustment outcomes.
• Experiential viewpoint:
Experience/practice becomes vital towards
facilitating motor development.
– Several studies have noted cultural differencies in motor development due to
child rearing practices.
– Iranian study (children spend 1st 2 yrs lying on backs in cribs/feeding, little
play—motor development significantly impacted. Delayed in talking, sitting
up, walking. 15% of the 3 to 4 year olds could walk.
• Dynamical Systems Theory viewpoint: Motor development
is an active reorganization of previously mastered capabilities that
are adjusted due to environmental exploration and curiosity dev.
Goldfield Study (1989)
• Infant’s emergence to crawling around 7 to 8 months.
– Regularly turned and raised their heads to interesting sights and sounds
– Developed distinct schemes for reaching and grasping
– Developed distinct schemes (leg thrust movements) to allow for greater mobility
• Infants development is goal directed
– While highly dependent of maturation and influenced by
experiences, the child is actively navigating and engaging the
environment and developing more complex schemes/talents
in the process of constructing his/her understanding of the
world
Fine Motor Development
• Birth – 3 months
– Innate and primitive reflexes (palmer grasp) evolve into more voluntary motor
movements/reaching (around 2 months).
• 3 months
– Refined fine motor skills and improved grasping
– Refined hand-eye coordination
• 4-5 months
– Refined ability to sit up and move their hands across their bodies.
– Develop hand to hand movements during transferring of objects and development of
ulnar grasp (grasping of objects by pressing fingers to palm.
• 6 months
– Pincer grasp develops (ability to use thumbs to counter the strength of fingers).
– Refined grasping techniques facilitates changes in play and exploration.
• Wheeled toys (once banged) are likely to be scooted; soft objects are likely to be squeezed.
Fine Motor Development Cont.
• As children get older, greater development of fine motor
skills.
– Parents and teachers facilitate development thru play/creativity
with crayons, blocks, markers, etc.
– Kids have yet to master speed with fine and gross motor
skills….Therefore, 2 to 3 yr olds may still have difficulty catching
and throwing a ball.
Exploring the New Environment
• As children develop greater awareness of their competencies,
they are truly experiencing a new environment.
– Children Explore….Parents Childproof.
– Children on the move……..Parents in Pursuit.
• Motor develop facilitates development across other domains
– Children with greater mobility are better able to explore relationships
with other people.
– Greater confidence due in part to their ability to retreat when they feel
appropriate.
– Children explore people as well as objects.
Role of Nutrition in Infancy
•
Deficiencies in nutrition during infancy can permanently stunt development, particularly in brain
functioning and development
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Breast feeding remains the healthiest option for ensuring infants obtain proper nutrients.
Advantages are as follows
– Correct balance of fat and protein. Human milk have higher fat content/lower protein.
Essential for brain development/ mylenization/ nervous system.
– Nutritional Completeness. Human milk has all that a child needs (1st 6 months). If bottle
feeding, you need iron supplementation
– Protection against diseases. Breast feed babies develop greater resistance against disease.
Receive antibodies from mom
– Protection against malocclusions & tooth decay.
– Digestibility. Different bacteria growth in body; less constipation and diarrhea
– Smoother transition to solid foods. Breast fed babies make a smoother transition to solid
foods. Due in part to a greater variety of experience in taste thru mother’s milk.
Nutrition/Breast feeding Cont.
• Breast feeding declined in the United States from 1940’s to
1970’s.
• The natural childbirth movement in the late 70’s brought a return
to breast feeding in US.
– Today, 2/3 of mothers breastfeed.
– Generally practiced among the well-educated and middle social class
mothers.
• Babies, from poverty-strickened areas, who are breastfed are
more likely to be healthy and survive their first year.
• Babies breast fed exclusively for the first 6 months would save
the lives of 1 million babies annually (Grant, 1995).