class 8 powerpoint

1. REACHIING THE AGE OF
ADOLESCENCE

2. Adolescents are:
• Age: 10-19
• 40.7 million

4. Initiation Rites
• Adolescence is a time of preparation for adult
responsibilities
• Many initiation rites (ceremonies or rituals in
which an individual is admitted to new status
or accepted into a new position) that mark
admission into adulthood
– Birthdays 16/18/21
– Graduation
– Weddings

5. Adolescence and Puberty
The period of life, when the body undergoes
changes, leading to reproductive maturity is
called
adolescence. It begins around the age of 11
years and lasts up to 18 or 19 years of age.
Adolescents are
also called ‘teenagers’, In girls, adolescence
begins a year or two earlier than in boys.
During adolescence, the human body
undergoes a number of changed. The testes
start to make sperms
and the ovaries start to make eggs. In other
words, the reproductive organs become
functional. The age
at which reproductive organs become
functionally active is called puberty. At
puberty, therefore the
boys and girls become capable of
reproduction.

6. Changes at Puberty
Growth of the body is an important character
during puberty. The different parts of the body
during
adolescence grow at different rates. Head,
hands and feet reach adult size very soon and
therefore look
disproportionately larger for some time. The
legs grow faster than the torso and then stop,
while the
torso continues to grow.

7. Change in body shape
During adolescence, changes in body shape
takes place. These changes are different in
boys and girls.
(i) The boys develop broader shoulders and
wider chest. In girls, the region below the waist
becomes wider.
(ii) Body muscles grow more in boys than in
girls.

8. At puberty, the voice box or the
larynx
begins to grow. Boys develop larger
voice
boxes. The growing voice box in
boys can
be seen as a protruding part of the
throat called Adam’s apple (Fig.
10.2). In girls,
the larynx is hardly visible from the
outside because of its small size.
Generally, girls have a high pitched
voice,
whereas boys have a deep voice. In
adolescent boys, sometimes, the
muscles
of the growing voice box go out of
control
and the voice becomes hoarse. This

9. Increase in Activity of Sweat and
Oil Glands
During puberty the
secretion of sweat glands
and sebaceous glands (oil
glands) increases. Many
young people get acne and
pimples on the face at this
time because of the
increased activity of these
glands in the skin

10. At puberty, male
sex organs like the testes and penis
develop completely. The testes also
begin to produce sperms. In girls,
the
ovaries enlarge and eggs begin to
mature. Also ovaries start releasing
mature eggs.

11. Emotional Development Adolescents have become sophisticated at
regulated their emotions
Adolescents are adept at interpreting social
situation as part of the process of managing
emotional displays
Adolescents develop a certain of expectations
Children begin to break emotional ties with
parents and develop them with friends
Boys will start to regulate (hide) their
emotions.
Adolescents also regulate their emotions
because of their sensitivity to other’s
evaluations of them
During adolescence (as early as age
10)….children begin to realize emotions aren’t
as simple as they thought when they were
children
Boys are less likely to display emotions of fear
as girls are
Displays of empathy also increase during
adolescence

12. These characters which develop at the time of attaining sexual
maturity and help to distinguish the male
from the female are called secondary sexual characters. Secondary
sexual characters are external
characters which are not directly involved in the process of
reproduction.
The changes which occur during adolescence are controlled by
chemical substances called hormones.
The hormones are produced in special organs celled endocrine glands.
There are a number of endocrine
glands in males and females of humans.

13. Secondary Sexual
Characters
Testosterone hormones produced by testis
brings about changes in boys and estrogen
produced by
ovaries in girls. Testosterone and estrogen
are called sex hormones.
The activity of testes and ovaries are under
the control of hormones from another gland
called the master
gland or pituitary gland. This gland is
located at the base of the brain.
* Endocrine glands have no ducts. For this
reason, they are also called ductless
glands
* The secretions of endocrine glands are
poured directly into the blood.
* The hormones are required in extremely
small quantities. Increase of decrease in
the specific
quantity is harmful of the body.

14. Hormones other than Sex Hormones
Apart from the pituitary, the testes and the
ovaries, there are other endocrine glands in
the body. Some
of the major ones include thyroid, adrenal and
pancreas.
(i) When a person has a very big and bulging throat, he is suffering from goiter, a disease, due to the
deficiency of the hormone thyroxin produced by the thyroid gland, and
(ii) When a person is suffering from sugar problems, it means that his pancreas is not producing
sufficient quantities of insulin hormone.
Similarly there is hormone adrenalin which helps the body to adjust the stress conditions (like when
one
is angry or other tension).

16. Reproductive Phase in Humans
The production of gametes starts earlier in females than in
males. In females, this phase begins 10 to 12 years of age while
in males, it beginning at 13 to 14 years of age. However, the
production of gametes lasts for a much longer time in males
than the females.
In females, the reproductive phase generally lasts up to the age
of 45 to 50 years. This period from the onset of puberty to the
age of 45-50 years is marked by a specific event repeated almost
every month.
During this period, one ovum matures and is released by one of
the ovaries once in about 28 days, and
the wall of the uterus becomes thick so as to receive the egg. In
case it is fertilized, it starts developing and results in pregnancy.
If fertilization does not occur, the released egg and the lining of
the uterus along with its blood vessels are shed off. As a result,
bleeding takes place in women. This loss of blood is called
menstruation. Menstruation occurs once in about 28 days. The
first menstrual flow begins at puberty and is called menarche.
Around the age of 45 to 50 years, the menstrual cycle stops. The
permanent stoppage of menstruation is called menopause.
Girls – Start to release eggs
Boys – Start to make
sperm cell

17. In the males, the least pair of
chromosomes consists of one X
chromosome and another Y chromosome.
In other words, in males sex chromosomes
are XY type.
In the females, both the chromosomes of
the last pair are same, and these of X
chromosomes. So, the sex
chromosomes in females are of XX type

18. Many drastic changes take place in
the life history of an insect and the frog,
during the process of
metamorphosis.
In insects, metamorphosis is controlled
by insect hormones. In case of a frog, it
is controlled by
thyroxine hormone. Presence of iodine
in water is a must for the production of
thyroxine. If the water in
which tadpoles are growing does not
contain sufficient iodine the
transformation of tadpoles into adult
cannot take place. Even in case of
humans, iodine is important for the
thyroxine hormone. It us for this
reason that the consumption of iodized
salt is recommended.

19. As the body is in a stage of rapid growth during
adolescence, nutritional needs are also more.
The diet
during this period has to e a balanced diet.
In such a diet, energy-giving (carbohydrates and
fats), body-building (proteins) and protective
foods
(vitamins and minerals) are present in requisite
proportions.
Milk is a balanced food in itself. Minerals like
iron and calcium are very important for all of us.
Iron is
essential for blood. Green leafy vegetables,
jaggery , meat, eggs, lemon and amla are rich
iron. Calcium
is required for bones and teeth. Rich source of
calcium are milk, cheese, green leafy
vegetables like
spinach, pulses, meat and eggs.

20. Personal Hygiene
The basic aim of maintaining personal hygiene is to keep the bacteria and other harmful
microorganisms
away from entering the body or infecting the food consumed by us. Otherwise, diseases
can
develop.
Following precautions need to be taken for maintaining personal hygiene:
(1) Before and after taking meals, always wash your hands with sap water.
(2) Clean your teeth after each mean and before going to bed. Otherwise tooth decay
may take place
(3) Take bath regularly with clean water.
(4) Do not grow long nails. Keep them short and clean
(5) The feet should be cleaned and well protected. Injuries due to bacterial like tetanus,
hookworms
and insects may be caused if barefoot walk is undertaken. Walking barefoot must be
avoided.
(6) Hairs should be cleaned regularly with soap and water. Combining removes the dirt
sticking to
hair.
(7) Eyes should be washed daily with clean and cold water. Rubbing of eyes with hands
should be
avoided to prevent the entry of germs into the eyes.
The waste food material and garbage should be disposed off properly. It should not be
thrown in the
open. Covered bins must be employed.

22. Adequate Exercise, Rest and Sleep
(1) Live a disciplined life
(2) Keep yourself away from tension, long
hours of television viewing and long hours of
continuous
table work.
(3) Take rest and regular sleep.
(4) Undertake exercise regularly. Brisk
walking, running, cycling and swimming are
some good
exercise. Exercises help in improving blood
circulation. They also help in keeping our
longs, heart
and body muscles healthy.
Exercise also helps in resisting infections and
building up health.

23. Say no to drugs
Adolescence is a period of much
activity in the body and mind which
is a normal part of growing up. So do
not feel confused or insecure. If
anybody suggests that you will get
relief if you take some drugs, just say
envoi unless prescribed by the doctor.
Drugs are addictive. If you take them
once, you feel like taking them again
and again. They harm the body in the
long run. They ruin health and
happiness.
You must have heard about AIDS
which is caused by a dangerous virus,
HIV. This virus can pass on to a
normal person from an infected
person by sharing the syringes used
for injecting drugs. It can also be
transmitted to an infant from the
infected mother through her milk. The
virus can also be transmitted through
sexual contact with a person infected
with HIV.