Puberty, Health and Biological
for Middle Childhood through Adolescence
School of Family and
Consumer Sciences 400.404/504
Instructor: D. Witt
On Biological and
Physical Development in Middle Childhood.
Development occurs most in the first three years of life
than any other period throughout development.
During middle childhood, it becomes slow and quite
irregular. At age 6, children generally weigh 45 pounds
and are 3.5 feet tall. Children continue to grow about 2
to 3 inches in height and 5 pounds in weight each year on
average, however such growth tends to occur in spurts that
happen at slightly different ages for boy and girls.
For Girls at ages 4.5,
6.5, 8.5, and 10
For Boys at ages 4.5, 7.0, 9.0 and 10.5
The Nature vs. Nurture
- During infancy and early childhood, children grow
from head to toe (cephalocaudally).
However, during middle childhood, we reverse in
development—we grow from bottom to top.
- In the early periods of
development, we also grow from center outward (proximodistally).
This development reverses during middle childhood,
with limbs growing faster than the trunk of the body.
- Also Females accumulate
more body fat (start getting "curves" after the age of
8 and continues throughout adolescence.
- NATURE - Good genes are passed thru next
generation. Bad genes are not passed
- NURTURE - Nutrition, Health, Disease control,
Family Resources play as big a part.
- SECULAR TRENDS - Changes in growth or body size
from one generation to another generation. Onset of
menarche - Menstruation has begun at slightly earlier
ages for girls with each passing century.
- SKELETAL DEVELOPMENT DURING MIDDLE CHILDHOOD
- Bones grow longer and broader
- Replacement of primary (baby) teeth with
permanent teeth (around ages 6-7 - Between ages 6
and 12, all 20 primary teeth are replaced
- Children lose their 1st at the
end of early childhood. Girls lose their teeth
earlier than boys
- The 1st teeth to go are central incisors (lower
and upper front teeth). - In 14% of cases, serious
difficulties in chewing and biting may result
- Malocclusion are generally caused by thumb
sucking after permanent teeth start coming in or are
- BRAIN DEVELOPMENT
- The frontal lobe increases in size and
maturity. Responsible for development of more
complex thought and end of self-consciousness.
Prefrontal cortex continues to grow throughout
- Brain development is highly attributed to
neurotransmitters—chemicals that allow communication
between neurons through synapses. Over time,
they become more selective and efficient
- When neurotransmitters are not balanced,
predisposed to epilepsy, ADHD, and emotional
disturbances - this is not the norm for the vast
majority of children.
- HEALTH RELATED PROBLEMS
- Infections/diseases are less prevalent in middle
childhood, unless diet and home discipline is poor -
related to poverty.
- Some 25% are affected with myopia
- 27% of children suffer from obesity (leading to
HB pressure, cholesterol, diabetes, respiratory
abnormalities, heart disease.
- There are some known factors associated with
childhood obesity, including heredity, social class,
early growth patterns (early developers), family
dietary habits, responsiveness to food ques, level
of physical activity, television viewing (by the
time a child reach high school, he or she has spent
25,000 hours watching TV), traumatic events.
The Onset of Rapid Biologically Induced Change
Defined as a biological phenomenon in which the human
body becomes capable of fertility. But it's about much
more than reproduction. Puberty is an awkward time in
the lives of Western adolescents.
The IMMINENT BIOLOGICAL TRANSITION must be integrated
with the social norms providing for its acceptance. That
means, depending on the particular social environment of
the individual, puberty can be easily accomplished or
may be met with resistance, conflicts and disagreements
as to its MEANING.
Genetic Influences on
Genes and Genetic Principles Individuals carry the
combined genetic code of their biological parents
through 23 pairs of chromosomes. Except for the general
"humanness" of the general genetic code for human
beings, each person's genetic code makes them unique.
"Every person is like every other, and at once, like no
The General Hereditary Code provides human
commonalities, such as:
Genotype is the
special arrangement of chromosomes & genes that
individualizes each person (genes for eye color, voice
timbre, height, weight, maybe even temperament). The
- physical similarities (anatomy, brain
structure, size, type-placement-number of internal
organs, skeletal form and function, number of eyes,
- psychological similarities (allowing for
the diagnosis of mental illness or the assessment of
mental health, similarities in cognitive processes).
Phenotype is the sum of all of a person's
physical and psychological features that can be observed
Genotype is potential outcome - Phenotype is actual
outcome. Any one phenotypical characteristic can be the
result of any genotypical arrangement, or due to
Environmental Interruptions, can be changed dramatically.
So Genetic Heredity plays a part, but only a part in
the final outcome of any given characteristic.
Biological determinants can be mitigated by social or
other environmental conditions.
Here's another example:: A genotype likely to produce
average intelligence could be interrupted by super diet
and strong family attitudes toward the value of
education - producing a "smarter than genetically
Polygentic Inheritance refers to the principle
that explains the importance of "interaction between
genetic effects" - as potential characteristics combine
in effect, the outcome is said to fall into a "reaction
range" of phenotypes. This suggests that environmental
events can alter the outcome phenotype. The extent to
which heredity determines the development of the person
often depends on the extent to which the
social/environmental conditions are CONDUCIVE to the
For example, society has often run in opposition to
biology: Chinese foot binding, scarification
rituals of circumcision, Anti-intellectualism in the
Western World. In other instances, genetic potential
stubbornly has its way in spite of environmental
Canalization refers to the narrow path of
development of some human characteristics - mainly the
general physical traits, but some psychological ones
adhere to natural human development over environment:
For example, while some abused children will learn to
emulate the behaviors they experience from abusive are
givers, MOST do not grow up to become abusers
themselves. Similarly, severely deprived children tend
to rapidly catch up on develop after deprivation is
The Heritability Quotient is a mathematical
equation for estimating how much more alike identical
twins are than fraternal twins - but it is useful in this
discussion as well. It states that biological heredity
declines in effect from most influential to least
influential in the following order:
This is true generally, however environmental intrusion
into normal development can trump nature if the
intrusion is powerful enough and more constant. This is
known as the continuum of indirectness - that the more
influence the environment may exert on a particular
trait, the less direct the influence of natural
Generally, physical characteristics are more
directly influenced by genes (barring such
events as cosmetic surgery, famine, war, accidents)
while psychological "tendencies" such as the
susceptibility to disease, native intelligence,
emotional traits, are less directly controlled by
Heredity/Biology is most
important for physical attributes, temperament,
development of psychosis, and risk of mental
retardation. Environment is most important development
of cognitive curiosity, development of interests and
Biological Processes, Puberty, and Physical
Development for Teenagers
General Features of Physical Growth &
All human beings follow the same 4 growth curves from
conception through the end of adolescence.
Factors influencing growth curves are the regulatory
principles of development
Growth Curves show the
relative increases or decreases in four areas of
growth as the child ages and matures. The more
constant the slope of the curve, the more continuous
the pattern of development.
Dramatic increases in growth define a "spurt" in that
- Skeletal growth - follows the General and most
continuous s curve. Included here is organ
development (kidneys, liver, etc.). The curve tends
to "spurt" during adolescence.
- Reproductive organ growth curve - dormant until
adolescence with rapid increases around 14 years of
age. Reasons for such dramatic increases: pituitary
and thyroid glands responsible for muscular and
skeletal growth are not the same ones that regulate
reproductive functions. Reproductive development is
sex hormones (produced in the gonads - androgen,
- Brain and head development starts rapidly and
begins to slow after adolescence (eyes, brain, ears,
skull). Head is usually the most developed part of
the body through age twenty.
- Lymphoid system and tissue development - tonsils,
adenoids, lymph nodes
Puberty - Instead of a single life event, puberty
is a process of development.
- Target Seeking/self stabilizing - interruptions of
normal development may retard normal growth until
crisis subsides. Then the individual tends to "catch
up" to normal growth..
- Maturity gradients - in different regions of the
- Cephalocaudal Development - development from the
- Proximodistal Development - development from the
- Feedback regulation - the teenage nose - growth
producing hormones from pituitary gland influence
secretions from gonads, hypothalamus until their
optimum levels are reached. Then pituitary gland shuts
down production for a while. No gland overproduces.
- Body Mass - the attainment of appropriate level of
body mass (usually at adolescence ages) - triggers the
beginning of puberty. For girls - 106+3 lbs.
Beginning about age 11 or 12 for girls and 13 or 14 for
boys, and continuing into the middle teens. Maturation of
sex organs and height and weight gain. The biological
meaning of puberty is that children are now able to
The simple biological truth.is that individuals are now
able to reproduce
The complex sociological problem.
- The endocrine systems effects - the hormonal system
that stimulates these physical changes secretes
hormones through the blood stream, where exocrine
glands (saliva, sweat, and milk glands are carried
through independent duct systems.
- Endocrine gland secretions (hormones) are powerful
biochemicals that stimulate other organs to growth. 6
The hypothalamus-pituitary-gonadal axis - in
adolescence, the pituitary gland is the main hormone
producer (the "master" gland). Located at the base of
the brain, the Pituitary regulates all other organs
during puberty.It stimulates the gonads (testes in
males and ovaries in females) to produce Androgens
(primarily in males) and Estrogens (primarily in
- The hypothalamus, located higher in the brain,
monitors the interaction n between pituitary gland and
gonads, regulating the optimal hormonal levels - and
- More precisely, testosterone is an androgen that is
increasingly produced throughout t puberty in males.
This is linked to development of secondary sex
characteristics (external genitals, increased height,
weight, and voice development, upper body strength,
pubic hair growth, etc.)
- Estradiol, is an estrogen that increases during
puberty for females. As increases occur, breast and
uterine development begin, menstrual cycles begin and
stabilize, and height, weight gains, etc. occur.
- Finally, the thyroid gland interacts with this whole
process to aid in development of skeletal maturation.
Physical Changes - height and weigh growth is achieved two
years earlier for girls than boys on the average. Making
for tenuous peer relations (tall girls, short boys).
Individual Variation in Puberty
Psychological Adaptation to Changes in Physical
Development in Adolescence
- For boys, puberty may being as early as age 10
and as late as 14.
- For girls, puberty may begin as early as age 10
and as late as 16.
- The pubertal process described in the text is
based on average results and the standard
distribution. Variations are more the rule.
Body Image - Adolescents show a great deal of
interest in their bodies.
Development of a poor body image may be the root cause of
eating disorders (anorexia, bulimia, overeating)
especially in young girls.
Sensitivity and dissatisfaction with body is more likely
in early adolescence than in late teens.
Generally, early developing girls and boys had higher
satisfaction with their bodies than late developers.
Early Maturation and late maturation
Menarche and the Menstrual Cycle - Range of reactions of
young girls to Menarche - most found it a wonderment, a
little upsetting, somewhat annoying later. But most really
found it a sign of maturity - a positive experience. Only
a minority of girls found periods to be debilitating g, or
to be associated with mood or emotion swings.
- Self Esteem -for early maturing boys, higher
self-esteem in sixth grade but differences disappear
by 9th grade -for girls, no difference in self-esteem
- Body Image -Early maturing boys and girls were less
satisfied with body (most probably their extra weight)
in sixth and seventh grades. -Early maturing girls
begin less satisfied, but by 9th grade, early maturing
girls were the most satisfied of all groups of girls.
- Opposite Sex Popularity -early maturing girls were
more popular and dated more from the sixth grade on
through high school. -Early Maturing boys were more
popular as well, but uninterested in girls so much as
- Academic Behavior -early girls score lower on
achievement tests, and many will drop out of high
school or miss college the first time.
- Independence - -early girls are more independent,
enjoy more freedom from parental control, more likely
to be left alone at home.