physical development chapter 6. prolonged period of physical growth prolonged period of physical...
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Prolonged period of physical growthProlonged period of physical growth Period between birth/puberty Period between birth/puberty
mice/rats (2% of lifespan)mice/rats (2% of lifespan) 7 years in chimpanzees (17% of 7 years in chimpanzees (17% of
lifespan)lifespan) 20% of total years to growth20% of total years to growth Why?Why?
Changes in Body SizeChanges in Body Size
Rapid changes during infancyRapid changes during infancy– By end of first year, height 50% greater By end of first year, height 50% greater
than birththan birth– End of second year, 75% greaterEnd of second year, 75% greater– Weight shows similar gainsWeight shows similar gains– If rate maintained, children would be 10 If rate maintained, children would be 10
feet tall and weigh over 200 pounds by feet tall and weigh over 200 pounds by age 10; 12 feet tall and weigh several age 10; 12 feet tall and weigh several tons by age 18tons by age 18
Changes in Body SizeChanges in Body Size
Slows in early and middle childhoodSlows in early and middle childhood
Sharp acceleration in pubertySharp acceleration in puberty
• Figure 6.1 Gain in height per year by males and females from birth through adolescence. At age 10 ½ , girls begin their growth spurt. Boys follow some 2 ½ years later and grow faster than girls once their growth begins. BASED ON TANNER, WHITEHOUSE, & TAKAISHI, 1966.
Changes in Body Changes in Body ProportionsProportions
Different ratesDifferent rates CephalocaudalCephalocaudal ProximodistalProximodistal Exceptions to growth trends in Exceptions to growth trends in
adolescenceadolescence
Changes in Body Changes in Body ProportionsProportions
Body proportions similar in infancy Body proportions similar in infancy and childhoodand childhood
Major differences occur during Major differences occur during adolescenceadolescence
Changes in Body Changes in Body CompositionComposition
Changes in muscle-fat makeupChanges in muscle-fat makeup Body fat increases pre/postnatallyBody fat increases pre/postnatally Peak 9 monthsPeak 9 months Slender starting in second year until Slender starting in second year until
middle childhoodmiddle childhood
Changes in Body Changes in Body CompositionComposition
Girls more body fat at birth – Girls more body fat at birth – increasesincreases
Around 8, changes begin through Around 8, changes begin through puberty for girlspuberty for girls
Opposite happens for boysOpposite happens for boys
Changes in Body Changes in Body CompositionComposition
Muscle different rate than fatMuscle different rate than fat Infancy/childhood Infancy/childhood slow slow Adolescence Adolescence rises rises In children, muscle composes 18-24% In children, muscle composes 18-24%
of body weight for both males and of body weight for both males and femalesfemales
By their mid-twenties, percent of body By their mid-twenties, percent of body that is muscle averages 24% for that is muscle averages 24% for females and about 40% for malesfemales and about 40% for males
Changes in Body Changes in Body CompositionComposition
Both sexes gain muscle at puberty, Both sexes gain muscle at puberty, gain is greater for boysgain is greater for boys– Develop larger skeletal musclesDevelop larger skeletal muscles– Larger heartsLarger hearts– Greater lung capacityGreater lung capacity– Number of blood cells increasesNumber of blood cells increases– Thus…?Thus…?
Skeletal DevelopmentSkeletal Development
Different ratesDifferent rates Skeletal ageSkeletal age Embryonic skeleton Embryonic skeleton cartilagecartilage Beginning at 6Beginning at 6thth week of pregnancy, week of pregnancy,
bones harden (bones harden (ossifyossify) – process ) – process continues throughout childhood and continues throughout childhood and adolescenceadolescence
Skeletal DevelopmentSkeletal Development
Skull Skull fontanellesfontanelles and and suturessutures Ankles, feet, wrists, hands develop Ankles, feet, wrists, hands develop
more bones more bones
Individual and Cultural Individual and Cultural DifferencesDifferences
Most differences within normal rangeMost differences within normal range Children at extremesChildren at extremes What accounts for differences in What accounts for differences in
growth?growth? Secular trends in physical growthSecular trends in physical growth
Individual and Cultural Individual and Cultural DifferencesDifferences
May be due to improved nutrition May be due to improved nutrition and healthand health– Orphaned babies from developing Orphaned babies from developing
countries countries – Low-income childrenLow-income children– Regions where poverty, famine, and Regions where poverty, famine, and
disease are widespreaddisease are widespread
Development of the BrainDevelopment of the Brain
100-200 billion neurons100-200 billion neurons Neural tube of embryoNeural tube of embryo Migrate and differentiateMigrate and differentiate By end of second trimester, By end of second trimester, mostmost
neurons are formedneurons are formed– Produce neurons?Produce neurons?– Brain can compensateBrain can compensate
Development of the BrainDevelopment of the Brain
SynaptogenesisSynaptogenesis– Infants more connections than adultsInfants more connections than adults– Neurons in synapse get crowded and dieNeurons in synapse get crowded and die
Neurons need stimulation to surviveNeurons need stimulation to survive– Synaptic pruningSynaptic pruning
Development of the BrainDevelopment of the Brain
If most neurons are produced If most neurons are produced prenatally, what accounts for prenatally, what accounts for increase in size of brain?increase in size of brain?– Glial cellsGlial cells– Myelinization Myelinization
Development of the BrainDevelopment of the Brain
Cerebral CortexCerebral Cortex– Largest structureLargest structure– Responsible for intelligenceResponsible for intelligence– Order of developmentOrder of development
Development of the BrainDevelopment of the Brain
3-6 3-6 frontal lobes frontal lobes 6-puberty 6-puberty temporal and parietal temporal and parietal
lobeslobes
MRIs were used to compare brain MRIs were used to compare brain activity in adolescents (10-18) and activity in adolescents (10-18) and adults (20-40) while processing adults (20-40) while processing emotional informationemotional information
Development of the BrainDevelopment of the Brain
LateralizationLateralization– When does it occur?When does it occur?– Tells us about brain plasticityTells us about brain plasticity– Lateralization has already begun at birthLateralization has already begun at birth– Lateralization not complete…Lateralization not complete…
Motor DevelopmentMotor Development
Sequence of motor skills sameSequence of motor skills same Large individual variationLarge individual variation Rate of motor development Rate of motor development ≠ ≠ future future
development outcomesdevelopment outcomes
Motor DevelopmentMotor Development
Gross motor developmentGross motor development
Fine motor developmentFine motor development
• Table 6.1 Age Norms (in Months) for Important Motor Developments (Based on
European American, Latino, and African American Children in the United States)
Motor DevelopmentMotor Development
Not a series of isolated, unrelated Not a series of isolated, unrelated accomplishmentsaccomplishments
Cross-cultural researchCross-cultural research
Motor DevelopmentMotor Development
Beyond Infancy: Motor Development Beyond Infancy: Motor Development in Childhood and Adolescencein Childhood and Adolescence– Each year, skills improveEach year, skills improve
Large muscles, eye-hand coordinationLarge muscles, eye-hand coordination
– Young children Young children overestimateoverestimate– Puberty – males increase in muscle Puberty – males increase in muscle
development; females tend to become development; females tend to become less activeless active
Hormonal Influences on Hormonal Influences on Physical GrowthPhysical Growth
Physical changes Physical changes endocrine endocrine systemsystem
HormonesHormones Pituitary glandPituitary gland Growth hormone (GH)Growth hormone (GH)
Hormonal Influences on Hormonal Influences on Physical GrowthPhysical Growth
GH GH body tissues except CNS and body tissues except CNS and genitalsgenitals
No prenatal growth, essential from No prenatal growth, essential from birth onbirth on
Lack GH Lack GH average mature height of average mature height of 4 feet 4 inches4 feet 4 inches
Catch-up growthCatch-up growth
Hormonal Influences on Hormonal Influences on Physical GrowthPhysical Growth
Sexual maturation Sexual maturation pituitary pituitary secretionssecretions
Estrogens Estrogens female hormones female hormones Androgens Androgens male hormones male hormones Both in each sex, different amountsBoth in each sex, different amounts
Hormonal Influences on Hormonal Influences on Physical GrowthPhysical Growth
Boys’ testes release large quantities Boys’ testes release large quantities of testosterone, which leads to of testosterone, which leads to muscle growth, body and facial hair, muscle growth, body and facial hair, and other male sex characteristics, and other male sex characteristics, also contributes to gains in body sizealso contributes to gains in body size
Estradiol causes the breasts, uterus, Estradiol causes the breasts, uterus, and vagina to mature and the body and vagina to mature and the body to take on feminine proportions, also to take on feminine proportions, also help regulate menstrual cyclehelp regulate menstrual cycle
Hormonal Influences on Hormonal Influences on Physical GrowthPhysical Growth
Adrenal androgensAdrenal androgens Not sure what sets hormonal Not sure what sets hormonal
processes in motionprocesses in motion– Combination of heredity, hormones, and Combination of heredity, hormones, and
body fatbody fat
Hormonal Influences on Hormonal Influences on Physical GrowthPhysical Growth
In girls, rise in body weight and fat In girls, rise in body weight and fat appears to play a role in sexual appears to play a role in sexual maturationmaturation– Serious athletic training/eat littleSerious athletic training/eat little– OverweightOverweight– Body fat Body fat ≥ 17%≥ 17%– Athletes, eating disordersAthletes, eating disorders
PubertyPuberty
Physically mature; produce offspringPhysically mature; produce offspring Changes in physical features related Changes in physical features related
to sexual functioningto sexual functioning– Primary sexual characteristicsPrimary sexual characteristics– Secondary sexual characteristicsSecondary sexual characteristics
PubertyPuberty
BoysBoys– Early maturation: advantaged in Early maturation: advantaged in
emotional and social functioning (seen as emotional and social functioning (seen as more relaxed, independent, self-more relaxed, independent, self-confident, and physically attractive; also confident, and physically attractive; also tend to be more popular, hold leadership tend to be more popular, hold leadership positions, and are athletic stars)positions, and are athletic stars)
– Late maturation: not well liked (seen as Late maturation: not well liked (seen as anxious, overly talkative, and attention anxious, overly talkative, and attention seekers)seekers)
PubertyPuberty
GirlsGirls– Early maturation: social difficulties (below Early maturation: social difficulties (below
average in popularity, withdrawn, lack self-average in popularity, withdrawn, lack self-confidence, hold few positions of leadership, confidence, hold few positions of leadership, more likely to be depressed, smoke/drink, have more likely to be depressed, smoke/drink, have an eating disorder)an eating disorder)
– Late maturation: physically attractive, lively, Late maturation: physically attractive, lively, sociable, leaders at schoolsociable, leaders at school
Advantages of maturing early and the Advantages of maturing early and the disadvantages of maturing late are greater disadvantages of maturing late are greater for boys than for girlsfor boys than for girls
Heredity vs. EnvironmentHeredity vs. Environment
Heredity Heredity hormones hormones NutritionNutrition
– Dietary diseasesDietary diseases MarasmusMarasmus KwashiorkorKwashiorkor
Infectious diseaseInfectious disease