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Principles of Physical Development
• Cephalocaudal - development from head
down.
Structural Example
Cephalocaudal Development
Functional Example
Principles of Physical
Development
• Proximodistal: development from inside
out
• Mass-to-specific: gross motor skills (large
muscles) develops first followed by fine
motor (small muscles) skills
Growth
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Newborn: 20 inches long; 7 1/2 pounds
1 inch per month
½ adult height by age 2
double weight by 4 months, triple by 12
months
• Head Circumference
• Fontanels
– Ossification
Growth
• Adolescence
– Puberty growth spurt - age 9 for girls, 11 for
boys
– Sexual maturation
Stages of Puberty
• Prepubescent Stage: no longer a child but not yet an
adolescent. Secondary sex characteristics begin to appear,
but the reproductive organs are not yet fully developed.
• Pubescent Stage : dividing line between childhood and
adolescence. Signs of sexual maturity appear - the
menstrual cycle in girls and the first nocturnal emissions in
boys. Secondary sex characteristics continue to develop.
Gametes are produced (not in the quantity/regularity of
Fully mature sex organs).
• Postpubescent Stage: Secondary sex characteristics
become well developed and sex organs begin to function in
a mature manner.
Male Secondary Sex Characteristics
• Pubic hair: appears about one year after the testes and the
penis have started to increase in size
• Facial/body hair appear when the pubic hair has almost
completed its growth.
• Muscles: increase markedly in size and strength.
• Voice: changes begin after some pubic hair has appeared.
Voice breaks are common when maturing is rapid.
• Heightened Emotions: Moodiness, sulkiness, temper
outbursts, anxiety and irritability. Testosterone can also
trigger a marked increase in aggressive behavior.
Developmental Order - Males
Female Secondary Sex Characteristics
• Hips: become wider and rounder due to enlargement of the
pelvic bone and development of subcutaneous fat.
• Breasts: shortly after the hips start to enlarge, the breasts
begin to develop.
• Hair: pubic hair appears. Auxillary hair usually begins to
appear after the first menstrual cycle.
• Voice: becomes fuller and more melodious.
• Heightened Emotions: Moodiness, sulkiness, temper
outbursts and a tendency to cry at the slightest provocation
These moods are especially common during the
premenstrual and early menstrual periods.
Developmental Order - Females
Growth
• Early Adulthood
– height remains constant
– muscle tone/strength peaks in late teens/20s
Growth
• Middle Adulthood
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loss of fat and collagen in skin tissues
aging spots
thinner,graying hair
lose 1/2 inch per decade in height, gain weight
bone density begins decreasing
Menopause
• Peri-menopause: transitional stage of two to ten
years before complete cessation of the menstrual
period (menopause). Age 35 to 50 years.
– decreasing levels of estrogen
– irregular menstrual periods
• Menopause: when a woman has gone through 12
months without menstruation (age 50)
– hot flashes, headaches, dizziness, heart palpitations,
joint pain, osteoporosis
Growth
• Later Adulthood
– weight loss
– osteoporosis
– osteoarthritis
Brain Development
• Human brain – most functional and bestorganized 3 pounds of matter in universe.
• Part of Central Nervous System
• Controls voluntary and involuntary
activities
• 2 Hemispheres with 4 lobes
Development of Brain
Brain
Lobes
Occipital lobe – vision
Temporal lobe – speech/language and hearing
Parietal lobe – sensory motor processes
Frontal lobe – critical thinking
Nervous System Development
The Birth and Growth of Neurons
• Most neurons formed halfway through
gestation
• Virtually no synaptic connections
– it is experience and interaction with the
environment that forms the synaptic connections
• 83% of dendritic growth (connections between
synapses) occurs after birth
Photographs of Human
Fetal Brain Development
Lateral view of the human
brain shown at one-third size
at several stages of fetal
development. Note the
gradual emergence of gyri
and sulci.
Childhood
• Synaptogenesis: most occurs through 2nd year of
life
• Myelination
• Lateralization
• Triples in weight by age 3
Use it or lose it – Natural
Selection of Brain Wiring
• Exposure to enriched environments with extra
sensory and social stimulation enhances the
connectivity of the synapses
• However, children and adolescents can lose
up to 20 million per day when not stimulated
Adolescence
• Brain is full adult weight by age 16
• Continued myelination
Aging Brain
• Loss of neurons
• Diminished functioning in remaining
neurons
• Changes in tissue surrounding neurons
• Declining levels of neurotransmitters
• Senile plaques
Brain Weight During Development and
Aging
Chronic Brain Disorders
• Dementia: general loss of intellectual
abilities
• Alzheimer's: brain atrophy; neurofibrillary
tangles
Themes of Development
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Continuity vs. Discontinuity
Early vs. Later Experiences
Nature vs. Nurture
Critical Periods