In boys, puberty begins when LH from the pituitary gland triggers the testes to secrete
testosterone. Testosterone causes the penis and testes to grow. Along with FSH from the
pituitary gland, testosterone also causes the testes to start making sperm. Testosterone
leads to the growth of pubic and facial hair, as well. In addition, it causes the shoulders to
broaden and the voice to deepen.
In girls, puberty begins when LH from the pituitary gland triggers the ovaries to secrete
estrogen. Estrogencausestheuterusandovariestogrow. AlongwithFSHfromthepituitary
gland, estrogen also causes the ovaries to start releasing eggs. Estrogen causes the menstrual
cycle to begin, as well. In addition, it leads to the growth of pubic hair. Estrogen also causes
the hips to widen and the breasts to develop.
Teen girls that are athletic may develop a condition called the female athlete triad. It occurs
when very active girls eat too few Calories to provide all the energy they need. Lack of
energy leads to low levels of estrogen. As a result, girls do not begin menstruating or their
menstrual periods stop. They also develop osteoporosis. This is a serious disorder in which
bones lose minerals and can break easily. The female athlete triad may have lifelong effects
on health. It can even be fatal. It requires medical treatment and an increase in Calories in
the diet.
Boys and girls are close to the same height during childhood. In both boys and girls, growth
in height and weight is very fast during puberty. However, boys grow faster than girls during
puberty. Their period of rapid growth also lasts longer. As a result, by the end of puberty,
boys are an average of 10 centimeters taller than girls.
Adolescence
Adolescenceis the period of life between the start of puberty and the beginning of adult-
hood. Adolescence includes the physical changes of puberty. It also includes may other
changes. During adolescence,
- teens develop new thinking abilities. For example, they can think about abstract ideas
such as freedom. They are also better at thinking logically. They are usually better at
solving problems, as well. - teens try to establish a sense of who they are as individuals. They may try to become
more independent from their parents. Most teens also have emotional ups and downs.
This is partly due to changing hormone levels. - teens usually spend much more time with peers than family members (Figure22.10).
The opinions of their peers are also very important to them. Most teens feel pressured
to dress and act as their peers do in order to be accepted.