It is only after the puberty sets in, humans become capable of reproduction. The class 8 science chapter 10, discusses the various changes that hormones are responsible for making a child grow into an adult. The period in life where the body undergoes change resulting in the reproductive maturity is termed as adolescence. It generally begins at the age of 11 and lasts up to 18 or 19 years. Adolescence in girls starts a year or two earlier than boys. During adolescence, the human body undergoes several changes marking the onset of puberty. The class 8 science chapter 10 discusses the various changes undergone at puberty and the role of hormones in this.
Changes at Puberty
Following are a few changes a boy or girl undergoes during puberty:
- Increase in Height – The bones of arms and legs elongate making the person tall
- Change in body shape – In boys, shoulders broaden and muscles of the body grow while in girls, waist becomes wider and muscles grow but not as much as boys
- Voice change – Larynx or the voice box begin to grow. Girls develop a high pitched voice and boys develop a deep voice
- Development of sex organs – Male and female sex organs develop completely. The testes in boys begin to produce sperms while in girls, ovaries enlarge and produce eggs.
- Emotional, intellectual and mental maturity – Brain has the greatest capacity to learn during this period and an adolescent may feel insecure and may spend considerable time thinking.
In addition to the listed changes, the breasts enlarge in girls and boys develop facial hair. These features help to distinguish between the male and female and are termed as secondary sexual characters.
Role of Hormones
Hormones control the changes that occur during adolescence. Hormones are secreted from endocrine glands. On the onset of puberty, male hormones called testosterone is released by the testes and female hormones known as estrogen is released by the ovaries. The production of these hormones is controlled by another hormone secreted from an endocrine gland known as the pituitary gland. The flowchart of the role of hormones in initiating the onset of puberty is given below
In females, the uterine wall prepares itself to receive the developing fertilised egg. If no fertilisation occurs, the thickened lining of the uterine wall breaks down and goes out of the body along with blood which is called menstruation. During adolescence, it is important to have a balanced diet and keep the body healthy. An individual’s health is regarded as the physical and mental well being of an individual.
Reaching The Age Of Adolescence Class 8 MCQ
- Reproductive stage in a women starts when
a. breasts start developing
b. height increases
c. menstruation starts
d. body weight increases
- Right meal for adolescents is comprised of
a. chapati, dal, vegetables
b. chips, noodles, coke
c. rice, noodles and burger
d. vegetable cutlets, chips and lemon drink
|NCERT Solutions for class 8 Science Chapter 10|
|NCERT Exemplar for class 8 Science Chapter 10|
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