Study Module & Revision Notes – Chapter 10: Reaching the Age of Adolescence

1. What is Adolescence?

The period of life when a child gradually changes into an adult is called adolescence. It is also known as the period of “growing up” or the “teenage years”. During this time, the body becomes capable of reproduction and many physical, mental and emotional changes take place.

Adolescence usually begins around the age of 11 years and continues up to 18–19 years. Therefore, boys and girls in this age group are called adolescents. The term “teenager” is often used because many of these ages end with the word “teen” (13, 14, 15, 16, 17, 18, 19).

2. Puberty – The Key Turning Point

The most important event during adolescence is puberty. Puberty is the period during which the reproductive organs become functional and the body shows characteristic changes. After puberty, boys and girls become capable of producing gametes and can reproduce.

Puberty does not start at the same exact age for everyone. On an average:

• Girls usually reach puberty between 10–12 years.
• Boys usually reach puberty between 12–14 years.

However, these ages can vary slightly from person to person. Factors like diet, health, genetics and environment can influence the exact age of onset of puberty.

3. Changes at Puberty

During puberty, the body shows several physical and emotional changes. Many of these changes are similar in boys and girls, while some are different.

3.1 Increase in Height

One of the most noticeable changes at puberty is a rapid increase in height, also called a growth spurt. Bones of the arms and legs grow quickly, so adolescents may suddenly look taller within a short period.

Growth does not stop immediately at the start of puberty. It usually continues till the age of about 18 years in girls and 19–20 years in boys. After that, the growth plates in bones close and height becomes almost fixed.

3.2 Change in Body Shape

As adolescents grow, their body shape also changes:

• In girls: The region below the waist becomes wider. Hips broaden and the body becomes more rounded.
• In boys: The shoulders become broader and the chest becomes wider. Muscles also develop.

These changes are related to the future roles in reproduction and child care.

3.3 Voice Change

At puberty, the voice box (larynx) grows. In boys, it grows much more than in girls. This makes the male voice deep and hoarse. The larynx in boys becomes more prominent and forms a bulge in the neck called the Adam’s apple.

For some time, the boy’s voice may crack or break. Later, it settles into a deep male voice. In girls, the larynx is smaller and the voice becomes only slightly shriller.

3.4 Increased Activity of Sweat and Sebaceous Glands

During adolescence, sweat glands and sebaceous (oil) glands become more active. This is why adolescents tend to:

• Sweat more easily.
• Have oily skin and sometimes develop pimples or acne.

Proper bathing and cleanliness become very important during this stage.

3.5 Development of Sex Organs

During puberty, the reproductive organs mature:

• Boys: Testes and penis enlarge. Testes start producing sperms.
• Girls: Ovaries enlarge and start releasing mature eggs (ova). The breasts also develop and the menstrual cycle begins.

3.6 Secondary Sexual Characters

Features that distinguish males from females but are not directly related to reproduction are called secondary sexual characters.

• In boys: Growth of moustache and beard, broad shoulders, more body hair on chest and arms, deeper voice.
• In girls: Development of breasts, broadening of hips, growth of hair in armpits and pubic region.

4. Role of Hormones in Initiating Puberty

Hormones are chemical substances secreted by endocrine glands directly into the blood. They act as messengers and control various activities of the body like growth, metabolism, and reproduction.

4.1 Endocrine Glands – The Hormone Factories

Glands which release hormones into the blood are called endocrine glands. They are also known as ductless glands because they do not have ducts.

Important endocrine glands in humans include:

• Pituitary gland – “Master gland” that controls other endocrine glands.
• Thyroid gland – Secretes thyroxine; controls metabolism and growth.
• Pancreas – Secretes insulin; controls blood sugar level.
• Adrenal glands – Help body handle stress and emergency situations (fight or flight).
• Testes (in boys) – Secrete testosterone.
• Ovaries (in girls) – Secrete oestrogen and progesterone.

4.2 Pituitary Gland and Puberty

The pituitary gland is situated at the base of the brain. At the onset of adolescence, it secretes hormones that:

• Control the general growth of the body (growth hormone).
• Stimulate testes in boys to produce testosterone.
• Stimulate ovaries in girls to produce oestrogen.

Thus, the pituitary gland indirectly controls the changes at puberty and the functioning of the reproductive organs.

4.3 Sex Hormones – Testosterone and Oestrogen

Testosterone (in boys) and oestrogen (in girls) are the main sex hormones responsible for the appearance of secondary sexual characters.

• Testosterone: Produced by testes; causes facial hair growth, broadening of shoulders, deep voice etc.
• Oestrogen: Produced by ovaries; causes development of breasts and broadening of hips.

5. Reproductive Phase of Life in Humans

The age during which humans become capable of reproduction is called the reproductive phase.

• In girls, the reproductive phase starts with the beginning of the menstrual cycle (menarche) and ends with menopause (around 45–50 years).
• In boys, the reproductive phase starts when the testes begin to produce sperms and continues for a longer period, often up to advanced age.

5.1 Menstrual Cycle – A Brief Idea

In girls, starting from puberty, the ovaries release one mature egg (ovum) approximately every month. The uterus prepares to receive a fertilised egg by developing a soft, thick lining with blood vessels. If fertilisation does not occur:

• The lining of the uterus breaks down.
• Blood and tissue are expelled through the vagina. This is called menstruation.

Menstruation occurs once in about 28–30 days. It is a regular and natural process and should not be considered shameful.

6. Sex Determination in Humans

Every human cell (except gametes) has 46 chromosomes, arranged in 23 pairs. One pair is called the sex chromosomes. They determine whether the baby will be a boy or a girl.

• Females have two X chromosomes: XX.
• Males have one X and one Y chromosome: XY.

During reproduction:

• All eggs (ova) from the mother carry the X chromosome.
• Half of the sperms from the father carry X and the other half carry Y.

If a sperm carrying X fertilises the egg (X), the zygote becomes XX – a girl. If a sperm carrying Y fertilises the egg (X), the zygote becomes XY – a boy. Therefore, the father’s sperm determines the sex of the baby, not the mother.

7. Nutrition, Personal Hygiene & Physical Exercise in Adolescence

7.1 Balanced Diet

Adolescence is a period of rapid growth. Therefore, adolescents need a balanced diet that includes:

• Protein-rich foods – pulses, milk, eggs, meat, nuts (for body building and repair).
• Carbohydrates and fats – rice, chapati, bread, oil, ghee (for energy).
• Vitamins and minerals – fruits, vegetables, salads, milk (for immunity and proper functioning of body).
• Adequate water and roughage (fibre).

Junk food, excessive soft drinks and very oily snacks should be avoided as they may cause obesity, fatigue and poor health.

7.2 Personal Hygiene

With increased sweating and oil secretion, adolescents must pay special attention to personal hygiene:

• Bath daily and keep the body clean to prevent bacterial growth and body odour.
• Wear clean clothes and undergarments.
• Take extra care of cleanliness during menstruation (use clean sanitary pads, change them regularly).
• Keep skin clean to reduce chances of acne and infections.

7.3 Physical Exercise and Adequate Rest

Regular exercise and outdoor games help in:

• Proper growth of bones and muscles.
• Good blood circulation and lung capacity.
• Reducing stress and improving mood.

Adequate sleep and rest are also essential for teenagers, as the body repairs and grows during sleep.

8. Emotional and Social Changes During Adolescence

Adolescents not only change physically, but also emotionally and socially. They may:

• Become more independent and want to take their own decisions.
• Feel confused or worried about changes in their body.
• Experience mood swings and strong emotions.
• Become more sensitive about how they look and what others think.

It is important for adolescents to talk to trusted elders, teachers or counsellors if they have doubts or worries. This period requires support, understanding and guidance from family and teachers.

9. Say “No” to Drugs and Harmful Habits

Some adolescents may face peer pressure to try harmful substances like tobacco, alcohol or drugs. These substances:

• Damage the brain, liver, lungs and other organs.
• Reduce concentration, memory and academic performance.
• Can cause addiction and serious diseases.

Adolescents should firmly say “No” to such habits and choose healthy hobbies and friends who support good behaviour.

10. Summary – One-shot Revision of Chapter 10

Adolescence is the transition period between childhood and adulthood, roughly between 11 and 18/19 years. It is marked by puberty, a stage when the body becomes capable of reproduction. The main changes at puberty are: increase in height, change in body shape, development of secondary sexual characters, change in voice, increased activity of sweat and oil glands, and maturation of sex organs.

These changes are controlled by hormones produced by endocrine glands. The pituitary gland is the master gland that controls other glands and triggers puberty. The sex hormones testosterone (in boys) and oestrogen (in girls) are responsible for the appearance of secondary sexual characters.

The reproductive phase starts at puberty. In girls it begins with the start of menstruation and ends with menopause. Sex determination in humans depends on the combination of sex chromosomes from parents. The father contributes either X or Y, while the mother always contributes X.

Adolescents need a balanced diet, personal hygiene, regular exercise, proper rest and emotional support for healthy growth. They should follow safe and responsible behaviour, avoid harmful substances like drugs and focus on building positive habits, values and skills.