This document summarizes the key physical changes that occur during adolescence for both girls and boys. It discusses that adolescence typically begins around age 11-13 and ends around 18-19. For girls, it notes changes like widening of the pelvis and hips to develop a female body shape, growth of pubic/underarm hair, onset of menstruation around age 12-13, and rapid height growth. For boys, it mentions growth of facial/body hair, enlargement of the genitals, development of muscles, growth spurts, and voice changes due to vocal cord thickening during puberty. It also provides details on menstruation, voice changes, and the location and function of the vocal cords

1. INTRODUCTION
SCIENCE SEMINAR
TEACHER- GULZAR BANU
CLASS- 8TH B
GROUP MEMBERS-NITYA
HARSHITH
YUG
PRASAD V.T
TOPIC- REACHING THE AGE OF ADOLESCENCE

2. The period of life, when the body undergoes
changes, leading to reproductive maturity, is called
adolescence. This is the time span in which the child
develops into an adult.
.Adolescence begins around the age of 11 and
goes on until 18 or 19 years of age.
•Adolescents are also called ‘teenagers’.
•The body at this stage undergoes important
changes and these mark the period of puberty.
What Is Adolescence?

3. Changes That Occur In A Girl During Adolescence:
In response to rising levels of estrogen,
the lower half of the pelvis widens. Fat
deposition occurs in the thighs, upper
arms, etc. This produces the typical
female body shape.
Hair grows in the pubic area, underarm
and leg.
Menstruation starts. The first menstrual
event is referred to as menarche. The
average age of menarche in girls is
about 12-13 years.
Hair and skin may turn oily.
A rapid increase in height or growth
spurt (girls, in general, reach their adult
height by about 16 years of age)

4. • Menstruation
One of the major changes that are observed in girls during
puberty is menstruation. Menstruation is also commonly
known as a period. But why does menstruation occur?
The female body prepares itself for pregnancy every month. If
fertilization does not occur it sheds the uterine lining through
menstruation. If fertilization does occur then there is no
menstruation.

5. Changes That Occur In A Boy
During Adolescence:
•The growth of hair on face, body, pubic area,
and unuder The growth of hair on face, body,
pubic area, and underarm , Rising levels of
testosterone promote the growth of the
genital organs.
•Overall physical growth-- boys develop
more muscle tissues, thicker as well as
larger bones and broader shoulders.
•Increase in size or growth of the penis,
testes and scrotum.
•Start having a spontaneous nocturnal
emission.
•The larynx grows and becomes
prominent and the voice changes in boys.
•a rapid increase in height or growth spurt
(boys, in general, reach their adult height
by about 18 years of age).

6. Voice Change:
Basically, the reason your voice changes as you get
older is because you get bigger and your vocal cords
enlarge and thicken. This is evident even before your
voice 'changes' as an adolescent
vocal cords (which are somewhat similar to guitar or violin strings), are small
and narrow, while yours are a bit larger and thicker. So in a sense your voice is
changing all the time as you're growing. However, the change you're talking
about is a pretty dramatic one, and it happens pretty quickly. At some point as
you are growing up (and it happens at a different time for everyone), you
enter a stage called puberty, which is when your body changes from a child's
to an adult's. One of the first things that happens is your body begins to grow
rapidly, due to hormones produced in the pituitary gland. These growth
hormones cause the larynx, or voicebox, to enlarge and the vocal cords to
thicken, which causes the voice to become lower in pitch and more resonant
in both boys and girls. Because this happens quickly, the voice seems to
change quickly, sometimes in a matter of a few days or weeks! The growth of
the larynx is in most cases more pronounced in boys than in girls -- most men
have a prominent 'Adam1s apple,' which is evidence of this. The larger larynx
also explains why most men's voices are in general lower than most womens.

7. VoiceBox in Throat: The voicebox (or larynx) is located in
the neck and performed several functions in the body. The
larynx works for breathing, swallowing, and production of
voice. When air passes through vocal cords produce sound
because passing air cause the vibration in the vocal cord
which generates sound waves in the pharynx, nose, and
mouth.
Where is Voice Box located in
Human?
Voice Box :
The nickname of Larynx is voicebox because it causes the
production of sound. Inside the larynx, there are two
stretched muscles called vocal cords. When we breathe inside,
the vocal cords open for giving the way to air, the air pass
through the larynx to the trachea and down to the lungs.
When we breathe out and talks, the vocal cords closed. Air
tries to pass through the closed vocal cords, which cause the
vibration that makes sound.