Chapter-10
Reaching the Age of Adolescence
The growth in the body is controlled by endocrine system.
Endocrine system controls these processes through chemicals
called hormones. Hormones are secreted by glands that make up
the endocrine system. These glands do not have ducts and
release the hormones directly into the blood. So, they are called
ductless glands.
A gland is a mass of cells in the body that produces chemical
substances.
There are certain glands with ducts as well. For example- Salivary
glands which secretes saliva which flows into your mouth
through small tubes called ducts.
Duct Glands Ductless Glands
1. Also called exocrine glands 1. Also called endocrine
glands
2. Secrete substances through 2.Secretes substances directly
ducts. into the blood.
3. Example: Salivary glands 3.Example: Thyroid and pituitary
and sweat glands glands
Hormones regulate many processes like growth, development
and behavior. Our body has around 30 hormones which are
needed in very small quantity.
The glands are located in different parts of the body. Hormones
generally do not act where there are released. They are taken by
blood to specific body part, called target organ, where they act.
Some of the glands are as follows:
1. Two adrenal glands are located just above the kidneys and
secrete adrenalin hormone when a person is angry or afraid. This
hormone prepares the body for the “fight or flight” reaction by
increasing the heart rate and blood pressure.
2. The pancreas secretes insulin which regulates the blood sugar
levels. Another function is to secrete pancreatic juice for
digestion of fats.
3. The thyroid gland produces hormone called thyroxine that
affects growth and development.
4. The ovary in females releases Estrogen and Progesterone
hormones. The testes in males produces Testosterone hormone.
These hormones control sexual characteristics.
5. The pituitary gland produces several hormones that control
water balance, growth and also the release of other hormones.
The growth hormone (GH) stimulates the growth and
development of the body. The thyroid stimulating hormone
(TSH) stimulates the thyroid gland to produce thyroxine. The
pituitary gland is called master gland as it influences the
functioning of the other glands.
PUBERTY AND ADOLESCENCE
The stage of life when body becomes capable of reproduction is
known as puberty. It is normally 11-16 in boys and 10-15 in girls.
When a child reaches puberty, he/she becomes an adolescent.
The period of transition from a child to an adult is known as
adolescence. It continues till the age of 18 or 19 years.
CHANGES AT PUBERTY
In boys, the male hormone testosterone begins to be released by
the testes. This causes sex organs to develop fully and start
producing the sperms.
In girls, the ovaries start producing estrogen and progesterone.
This causes ovaries to enlarge and start releasing eggs.
In addition to above changes, there other changes are also seen
which are called secondary sex characteristics. Some of them are
as follows:
1. Increase in height: There is sudden increase in height due to
elongation of bones of arms and legs. The height attained by an
individual is controlled by their genes. It is important that body
gets correct nutrition in this period to ensure healthy growth of
bones and muscles.
2. Changes in body shape: In boys, shoulders become broader and
chest wider. The muscles grow more in boys than girls. In girls,
the pelvic region widens, hips become broaden.
3. Development of hair: In both males and females. Hair start
growing in armpits and other areas. In boys, facial hair develops.
4. Voice changes: The voice box or the larynx begins to grow. It
becomes bigger in boys than in girls. This is why boys develop
deep voice whereas the girls develop high pitched voice.
5. Activity of sweat and oil glands: There is an increase in activity of
oil and sweat glands. This leads to increased sweating often
resulting in body odour. The skin becomes oilier. This often leads
to acne and pimples on the face.
6. Changes in attitude and behavior: Intellectual development
occurs during adolescence to transform an individual from a
child to an adult. Trying to adjust with the changes in body leads
to state of confusion and insecurity.
