Reaching The Age of Adolescence

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Growing up is something of a natural process. The period of life is called puberty, when the body undergoes changes leading to reproductive maturity.

Adolescence begins at around the age of 11 and lasts up to age 18 or 19. As this period covers the (age of 13 to 18 or 19) adolescents are also called adolescents. Adolescence, in girls, may start a year or two earlier than in boys. The teenage period varies, too, from person to person.

Throughout puberty, the human body undergoes many changes. Those changes mark the beginning of puberty. The most significant change which marks puberty is the ability of boys and girls to reproduce. Puberty terminates when a teenager reaches reproductive maturity.

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Changes at Puberty

Increase in Height:

During puberty, the most conspicuous change is the sudden height increase. At this time, the long bones, i.e. the arms and legs, lengthen and make a person tall.

Change in Body Shape:

A boy's body is getting more muscular. His shoulders grow wide, and the waist narrows. A girl's body is broader at the neck below the hip, then shorter.

Voice Change:

A boy's voice becomes deep, and a hoarse voice replaces the childlike voice at first. This is because they say the voice is cracking. Gradually, the voice deepens. The change in voice occurs because a boy's voice box is getting bigger. The voice of girls is usually pitched high.

Increased Activity of Sweat and Sebaceous Glands:

During puberty, sweat production and sebaceous glands increase. Some teens may suffer from acne and pimples because of this.

Development of Sex Organs:

Tests begin producing sperms in youth. Testis and penis fully develop. In girls, ovaries grow larger and eggs start maturing. Ovaries begin to release mature eggs.

Reaching Mental, Intellectual and Emotional Maturity:

Those changes also have a profound effect on the way of thinking of a person. Teenagers are spending more time thinking than they used to before. So, in most adolescents, many rapid changes in the body can create a sense of insecurity. But adolescents shouldn't worry, as these are natural changes. Definitely, they'll go away with time.

Adam’s Apple:

The expansion of the voice box is evident as a prominent protrusion in the neck. This protrusion is termed Adam’s apple.

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Secondary Sexual Characters:

Secondary sexual characters are traits that occur in humans during adolescence, and in other species at sexual maturity. These are the characters which differentiate a male from a female.

Secondary Sexual Characters in Males:

  • Growth of body hair, chest hair, pubic hair, underarm, abdominal, facial hair.

  • Muscle mass and strength is increased.

  • Body fat percentage is lowered.

  • Larynx (Adam’s apple) is enlarged and his voice is changed.

Secondary Sexual Characters in Females:

  • Breasts are grown and Erection of nipples.

  • Growth of body hair, most prominently pubic hair and underarm.

  • Widening of hips.


Hormone regulates changes that occur during puberty. Hormones are molecular components. These are endocrine gland secretions, or endocrine system. The testes start releasing the male hormone or testosterone at the onset of puberty.

This causes changes in boys, for example. the growth of facial hair, about which you have just learned. Once puberty is achieved in girls, ovaries start producing the female hormone or estrogen that causes the breasts to develop.

Glands that secrete milk or mammary glands grow inside the breasts. Such hormones are produced under the influence of another hormone which is secreted from an endocrine gland called the pituitary gland.

Role of Hormones in Initiating Reproductive Function

Endocrine glands secrete hormones into the bloodstream to get to a specific part of the body called the target site. The target site is hormone sensitive. There are many endocrine glands in the body, or ductless glands. Hormones control attaining the age of adolescence.

Sex hormones are secreted by the testes and ovaries. Furthermore, the pituitary gland controls sex hormones. Some hormones are secreted by the pituitary, one of which helps ova mature in the ovaries and sperm in the testes.

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Reproductive Phase of Life in Humans

When their testes and ovaries start producing gametes, adolescents become capable of reproduction. In males, the ability to mature and produce gametes lasts much longer than in females. The reproductive phase of life in females begins at puberty (10 to 12 years old) and generally lasts until the age of about 45 to 50 years.

With the onset of puberty, the ova start to mature. One ovum matures, and is released once in about 28 to 30 days by one of the ovaries. The wall of the uterus becomes thick during this period in order to receive the egg if it is fertilized and begins to develop. This triggers pregnancy.

The released egg and the thickened lining of the uterus along with its blood vessels are cast off if fertilization does not occur. For women, this triggers bleeding which is called menstruation. Menstruation happens every 28 to 30 days or so. The first menstrual flow starts in puberty and is called menarche.

The menstrual cycle stops at age 45 to 50. The Menstrual stoppage is termed menopause. Menstrual cycles can initially be irregular. It takes a bit of time to get normal.

Hormones control the menstrual cycle. The cycle includes egg maturation, release, uterine wall thickening and dissolution if no pregnancy occurs. For further growth, if the egg is fertilized, it begins to divide and then is lodged in the uterus.


Reaching the age of adolescence class 8 NCERT topic covers all related topics under adolescence like physical and mental changes during puberty, various hormonal changes seen in the body and detailed view of reproductive phase in human life.

FAQ (Frequently Asked Questions)

1. How is the Stage of Growth From 11 Years to 18 19 Years of Age Called?

Ans. The period of life is called puberty when the body undergoes changes that lead to reproductive maturity. Puberty begins at age 11 and lasts up to age 18 or 19. Since this period includes teenagers (ages 13 to 18 or 19), teens are also referred to as adolescents.

2. What is the Difference Between Puberty and Adolescence?

Ans. Puberty is the period during which the immature reproductive system matures in boys and girls and becomes reproductive competent. It is related to the physical changes. Adolescence is a period of mental and emotional changes experienced by boys and girls when attaining sexual maturity.

3. Explain Adam's Apple in Brief From Class 8 Biology Reaching the Age of Adolescence?

Ans. Boys build a wider voice box, and this voice box can be seen plainly from the throat. Adam's Apple looks like a little small apple before his mouth.

4. What is the Most Important Change During Puberty?

Ans. The most important change indicated by puberty is the sex organ’s growth and development. sex hormone production is triggered and gametes formation is seen. To males, the testes begin testosterone secretion and spermatogenesis begins.