CH5 - Physical development

Question 1

Time infants reach half their adult size:

Answer 1

boys: 2 years
girls: 18 months

Question 2

Features of human growth

Answer 2

Muscles become longer & thicker as individual fibers fuse together (boy puberty)

Layer of fat first appears under skin near end of the fetal period; continues to accumulate rapidly during the first year after birth (baby fat)
Increase in weight for high risk obesity noticeable by age 4

Bone starts as cartilage, middle of tissue turns to bone, shortly before birth ends (epiphyses) turn to bone

Question 3

Secular growth trends

Answer 3

changes in physical development related to environmental factors through generations (normal does not equal average)

Question 4

Mechanisms of physical growth

Answer 4

Heredity - .7 correlations between child’s height and average of both parents

Hormones - pituitary secretes growth hormone (GH) during sleep or after exercise, travels to the liver, liver releases somatomedin which causes growth of muscles & bones (dwarfism = GH deficiency)
Thyroxine released by thyroid gland allows for nerve cells to devel properly - anxiety related problems? Caused by alcohol consumption during pregnancy?(rats)

Question 5

Nutrition

Answer 5

40% of energy devoted to growth in a 2 month old (rest to digestion, respiration) - need 100-120 cals per kg of body weight per day until 2 yrs

Malnutrition - 16.9 million children under age 5 → indistinguishable physically but lower intelligence tests & difficulty maintaining attention. Solution: food availability, nutrition education & behavioral change

Diseases - 5.9 million children under age 5 dead - birth complications, pneumonia, birth asphyxia, diarrhea, malaria (45% related to malnutrition)

Question 6

Developing nervous system (neurons & axons)

Answer 6

Axons acquire myelin at 4 months - first sensory info, cortex last

After birth: brain grows rapidly, axons & dendrites grow longer, dendrites sprout new limbs (increasing # synapses)

Synaptic pruning = downsizing cuz of useless connection after 1st birthday

Question 7

Early neuronal development

Answer 7

3rd week - area of ectoderm thickens and forms neural plates - neural folds form neural tube
4 weeks - bulges and bends form primary vesicles: prosencephalon (cerebrum), mesencephalon, rhombencephalon (brain stem & cerebellum)
11 weeks - resembles total structure

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Question 8

Forms of neuroimaging:

Answer 8

EEG - electrical activity, brain waves, good temporal
fMRI - magnetic field to track blood flow
PET - traces glucose
fNIR or functional near infrared spectroscopy - measures blood flow, silent, unclear spatial image in deep brain areas

Question 9

avoidance & brin structures

Answer 9

Left frontal cortex regulates emotions stemming from tendency to approach, right = avoidance

Question 10

Motor development

Answer 10

fine motor skills (grasping, manipulating objects); gross-motor skills

Question 11

Motor development - innate reflexes

Answer 11

Babinski, grasping/palmer, rooting, sucking, stepping, blinking, moro (monkey), swimming (6), tonic neck (most disappear 3-4 months months)

Question 12

Dynamic systems theory (motor development)

Answer 12

Coordinating skills - understanding specific tasks (differentiation) to make up whole situation (integration)

Question 13

Locomotion

Answer 13

sit upright with support (4 months), sit (7 months), stand w support (9 months), walk with assistance (14 months), climb, walk backward, kick ball (24 months)

Stepping - 10 months, by 6/7 months understands alternating steps

Question 14

Posture & balance

Answer 14

cephalocaudal growth - use inner ear cues after a few months

Question 15

Fine-motor skills

Answer 15

Reaching & grasping but uncoordinated (4 months), coordinated at 5 or 6 months, pick up food at 6 months, eating with spoon at 1 year (2 year olds use wrist), hand positioning & thumb use (7 or 8 months)

Question 16

Sensory & perceptual processes - Smell, taste, touch

Answer 16

receptors are functional in the fetus and useful to newborns

Question 17

Hearing

Answer 17

fetus can hear at 7 or 8 months, infants do not hear well as adults - higher auditory threshold (low), recognize name by 4.5 months, using sound to estimate difference by 7 months, full auditory capacity at 30 months

Question 18

seeing - light, tracking moving objects

Answer 18

6 meters vs 60-120 m in adults & basically 1 year olds

Question 19

cones

Answer 19

Infants respond to higher saturation levels than adults can perceive (cones in retina circuits functioning at 3 months

Question 20

perceptual consistencies (seeing)

Answer 20

Size consistency by 4 or 5 months, most others at 4

Question 21

Depth

Answer 21

Visual cliff - 1.5 month old notices a difference, 7 month old perceives depth (fears cliff)

7 month olds use linear perception & texture gradient

Question 22

Edges

Answer 22

infants have 2 separate visual systems, one for perception of objects and one for interpreting visual stimuli from moving objects
1 month olds focus on edges of phase while 3 month olds focus on face features