PSEB 8th Class Science Notes Chapter 10 Reaching the Age of Adolescence

This PSEB 8th Class Science Notes Chapter 10 Reaching the Age of Adolescence will help you in revision during exams.

PSEB 8th Class Science Notes Chapter 10 Reaching the Age of Adolescence

→ It is after growing up to a certain age that human beings and other animals become capable of reproduction.

→ On crossing the age of 10 or 11 in human beings there is a sudden spurt in growth.

→ Growth is a natural process.

→ The period of life when the body undergoes changes, leading to reproduction maturity is called adolescence.

→ Adolescence begins at the age of 11 and lasts upto 18 or 19 years of age.

PSEB 8th Class Science Notes Chapter 10 Reaching the Age of Adolescence

→ Adolescents are also called teenagers.

→ The human body undergoes severe changes during adolescence which marks the onset of puberty.

→ The most conspicuous change during puberty is height.

→ The rate of growth in height varies in different individuals.

→ All the body parts do not grow at the same rate.

→ Height also depends on the genes inherited from parents.

→ At puberty, the voice box begins to grow. Generally, girls have a high-pitched voice, whereas the voice in boys is deep.

→ During puberty, the secretion of sweat glands and sebaceous glands also increases.

→ Endocrine glands release hormones directly into the bloodstream.

→ Adolescence is also a period of change in a person’s way of thinking.

→ The appearance of secondary sexual characters helps in distinguishing males from females.

→ Changes occurring in adolescence are controlled by hormones which are the chemical substances secreted by endocrine glands.

PSEB 8th Class Science Notes Chapter 10 Reaching the Age of Adolescence

→ Hormones are secreted by endocrine or ductless glands.

→ The endocrine glands are the pituitary, adrenal, thyroid, and gonads.

→ The pancreas is an exocrine as well as an endocrine gland.

→ Pheromones are the hormones present in insects.

→ An endocrine gland does not have a duct and is, therefore, also called a ductless gland.

→ A ductless or endocrine gland pours its secretion into the circulatory system of the body for sending to the target cells.

→ Secretions of endocrine glands are called hormones.

→ Testes or male gonads are mixed organs that produce sperms as well as male sex hormones or androgens (e.g., testosterone, androsterone).

→ Ovary secretes estrogen and progesterone hormones.

→ The cyclic changes that occur every 28 days (lunar month) in the reproductive tract of human females from the period of puberty to the age of menopause are called the menstrual cycle.

→ At the age of 45-50 women stop menstruation. It is called menopause.

→ There are 23 pairs of chromosomes in humans.

PSEB 8th Class Science Notes Chapter 10 Reaching the Age of Adolescence

→ There are 22 pairs of autosomes and 1 pair of sex chromosomes in human beings.

→ The change from larva to adult is called metamorphosis. These changes are also controlled by hormones.

→ The physical and mental well-being of an individual is regarded as an individual’s health.

→ Diet for an adolescent has to be carefully planned as it is a stage of rapid growth and development.

→ Personal hygiene is more necessary for teenagers because the increased activity of sweat glands makes the body smelly.

→ All adolescents should take walks, do exercise and play other games.

→ Adolescence: Children between the ages of 10 or 11 years to 18 or 19 years are called adolescents. This period of the age is called adolescence.

→ Puberty: It is a period (11 to 18 years) when the reproductive organs start functioning.

→ Voice Box: It is a box consisting of cartilages present in the throat of human beings causing voice.

→ Adam’s Apple: In boys, the growing voice box is seen as a protruding part of the throat called Adam’s apple.

→ Secondary Sexual Characters: In boys and girls some characters are present which helps to distinguish them. These are called secondary sexual characters.

→ Endocrine Glands: The ductless glands present in animals which secrete hormones and pour them directly into the bloodstream are called endocrine glands.

→ Hormones: These are the chemical secretions secreted by endocrine glands to control the activities of the human body.

→ Target Site: It is a particular body part where hormones released by the endocrine glands through the bloodstream reach.

→ Pituitary Gland: It is a master gland present in the brain.

PSEB 8th Class Science Notes Chapter 10 Reaching the Age of Adolescence

→ Testosterone: It is a male hormone secreted by the testes at the onset of puberty.

→ Estrogen: It is a female hormone released by the ovaries at the onset of puberty which makes the breasts develop.

→ Sex Chromosomes: Human beings have 23 pairs of chromosomes. One pair out of them (23rd pair) is called a sex chromosome.

→ Thyroxine: It is a hormone secreted by the thyroid gland situated in the neck.

→ Insulin: It is a hormone secreted by the pancreas which controls sugar levels in the blood.

→ Adrenalin: It is a hormone secreted by the adrenal gland which maintains the salt balance in the blood.

→ Balanced Diet: A diet that contains the various components of food (carbohydrates, fats, proteins, minerals, vitamins, water) in the right proportion.

→ Health: The physical and mental well-being of an individual is regarded as an individual’s health.

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