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Health Sciences 2711A/B Chapter Notes -Sex Organ, Pubic Hair, Secondary Sex Characteristic

Health Sciences
Course Code
HS 2711A/B
Treena Orchard

of 15
HS 2700A
November 9, 2009 Readings - Notes
Berk pp. 283-299
adolescence - the transition between childhood and adulthood
puberty happens during adolescence - there is a biological and social explanation
Hall described adolescence a period being very turbulent
Anna Freud (daughter) resembled adolescence as biologically based, universal
“developmental disturbance”
psychological disturbances rises only slightly from childhood to adolescence
Margaret Mead - studied adolescence in Samoa
they had a relaxed culture and relaxed social relationships, openness towards
therefore, adolescence was the best time for a Samoan girl/boy
Mead looked at it as if social experiences were entirely responsible for
Today, biological, social, and psychological development contribute to our
biological changes are universal and it happens to all people
demands and pressures of adolescence depends on each culture
some cultures transition from childhood to full assumption of adult roles
in industrialized countries, young people face those adolescent years where they
depend on their parents and postponement of sexual gratification
Puberty: The Physical Transition to Adulthood
girls reach puberty 2 years earlier than boys
Hormonal Changes
complex hormonal changes occur at around age 8 or 9
secretion of Growth Hormone (GH) and Thyroxine increase
gains in body size and attainment of skeletal maturity
estrogen and androgens (testosterone) are both sex hormones that are
BOTH present in males and females (just have different amounts for each sex)
testosterone leads to muscle growth, facial hair, and other male characteristics
the boysʼ testes also secrets a very small amount of estrogen
in both sexes, estrogen increases the secretion of GH
androgens stimulate gains in bone density
estrogen contributes to the growth of female body parts and the menstrual
adrenal androgens: secrete hormones that influence girlsʼ growth spurt and
pubic hair
boys are impacted on mainly the androgens and estrogen released from the
Body Growth
growth spurt: first outward sign of puberty; the rapid gain of height and weight
girls: around 10 yrs old and boys: around 12.5 yrs old
growth in body size is finished for girls around 16 yrs old and finished for boys
around 17.5 yrs old
adolescence adds about 10-11 inches in height and 50-75 pounds of weight
Body Proportions
limbs accelerate first, but then during puberty, the torso accelerates
boysʼ shoulders broaden and girlsʼ hips widen
in the end, boysʼ legs are much longer because they had 2 extra years of
pre-adolescent growth
Muscle-Fat Makeup and Other Internal Changes
girls start to accumulate fat around the age of 8 but accelerates from 11-16
yrs old
fat decreases in adolescent boys
both sexes gain muscle, but there is a bigger increase with boys
boys develop larger hearts, lungs, and skeletal muscles, therefore, the
number of red blood cells increase as well for boys
Motor Development and Physical Activity
girlsʼ gains are slow and gradual and usually level off by 14 yrs old
boysʼ gains are dramatic, and immediate in terms of speed, strength, and
boys: athletic competence is strongly related to peer admiration and self-
some boys become so obsessed that they take drugs like steroids
3% of North American high school students, mostly boys, report to be taking
anabolic steroids
teens who take steroids usually have lots of acne, mood swings, lots of body
hair, high blood pressure, aggressive behaviour, and damage to liver and
circulatory system, and reproductive organs
sports not only improve motor performance, but they also improve cognitive
and social development
in highschool, only 65% of Canadian students are enrolled in PE classes
Sexual Maturation
primary sexual characteristics: growth of penis, ovaries, vagina, testes, etc
secondary sexual characteristics: breast development, more pubic hair
Sexual Maturation in Girls:
begins with budding of the breasts and growth spurt
menarche - first menstruation, happens at around 12.5 yrs old
breast and pubic hair growth are completed
Sexual Maturation in Boys:
first sign is the enlargement of the testes
changes in texture and colour of the scrotum
pubic hair emerges and then penis begins to enlarge
growth spurt occurs much later for boys (compared to girls)
facial and body hair, deepening of the voice
while penis is enlarging, prostate gland and seminal vesicles enlarge
spermarche - first ejaculation at around 13.5 yrs old
Individual Differences in Pubertal Growth
heredity plays a role in puberty and when it occurs
identical twins usually reach menarche within a month or two apart from each
other, and fraternal twins usually menarche within 12 months apart from each
nutrition and exercise also contribute to puberty
sharp rise in body weight and fat may trigger sexual maturation
fat cells release leptin - a protein that signals to the brain that girlsʼ energy
stores are sufficient for puberty
girls who are obese and overweight reach puberty earlier and in contrast, girls
who train and are very athletic reach puberty later
in third world countries with poverty and malnutrition, puberty is reached much
later (14-16 yrs old)
girls exposed to family conflict tend to reach menarche earlier, as opposed to
those with warm family ties.
secular trend - generational change ; in pubertal timing lends added support to
the role of physical well-being in pubertal development
age of menarche steadily declined over the years (better sanitation, nutrition,
consequence: girls who reach puberty earlier will have to face unfavourable
peer involvements, including sexual activity
Brain Development
growth and stimulation of myelinated nerve fibers accelerate connections in the
during puberty, neurons become more responsive to excitatory
neurotransmitters (thus, adolescents react more strongly to stressful events
and experience more pleasurable stimuli more intensely)
they are more susceptible to drug use, eating disorders, depression, and
emotional pain
revisions occur in the brain where it controls sleep, that is why adolescents go
to bed much later than usual, but still need the same amount of sleep as
children (about 9 hrs)
The Psychological Impact of Pubertal Events
generations ago, menarche was considered to be traumatic
it is important to receive prior warning, and mothers are usually the ones who
discuss about menarche to their daughters
a fatherʼs involvement reflects a family atmosphere that is highly accepting of
physical and sexual matters
most boys know about spermarche ahead of time, but no one spoke to them about
boys who are better prepared tend to act more positively
mostly all girls tell different girls that they are menstruating, but boys do not share
anything about ejaculating to their fellow peers
boys get less social support than girls when undergoing puberty
many tribal communities celebrate the onset of puberty through a initiation
Pubertal Change, Emotion, and Social Behaviour