REACHING THE AGE OF ADOLESCENCE | SPEED NOTES | SCIENCE | CBSE | CLASS 10

Chapter – 10 Reaching the age of Adolescence

Humans become capable of reproduction after puberty setsin. Between theages of 11years and 19years children arecalled adolescents. The onsetof puberty brings about growth of the reproductive organs. Hairs growat various places on the body. Breasts develop in girls and facial hair (moustache and beard) appear in boys. Voice of boys become hoarse as voice box enlarges duringadolescence. Children gain height during adolescence.

Puberty: It is the time when sex organs begin to work. It brings about growth in reproductive organs and changes in the body. Puberty starts at the beginning of adolescence. The onset of puberty starts much earlier in girls, between 8 and 13 yearsof age, whereas it starts between 10 and 14years of agein boys andlasts upto 2to 4 years.

Changes during Puberty: (i) Increase inHeight: The bones ofthe legs andarms elongate andthe individual becomes tall and lanky.

(ii) Changes inBody Shape: In boys,the body becomes more muscular, theshoulder becomes wider. In girls, the body shows curves in certain parts and the region below thewaist become wider and broader.

(iii) Change in Voice: In boys,the voice becomes hoarse and heavydue to theextra growth oflarynx (voice box). In girls, thevoice becomes highpitched and shriller.

(iv) Sweat andsebaceous glands: Theybecomemore active andsecrete more sweat and oil. Pimples or acne appear due to increased action of sebaceous glands or oil glands.

(v) Emotional aspects develop.

(vi) Mental and intellectual development is atits peak.

(vii) The sex organs grow and become functionally active. The testes start producing male gametes, called sperms. Theovaries grow andrelease one mature ovum in a periodic cycle of 28 days. The onset of puberty andmaturity of reproductive parts are controlled by hormones.

Hormones are secretions of endocrine glands which pour them directly into the bloodstream. Pituitary gland secretes hormones which include growth hormone andhormones that make other glands such as the testes, ovaries, thyroids and adrenals, secrete hormones. Pancreas secretes insulin, thyroid produces thyroxin and adrenals produce adrenalin. Testosterone is the male hormone and estrogens, the female hormone. The uterine wallin females prepares itself to receive the developing fertilised egg. In casethere is no fertilisation, the thickened lining of the uterine wall breaks down and goes out of thebody along withblood. This iscalled menstruation. Sperm and Ovum fuses together to form a zygote. Sex chromosomes in sperms determine the baby’s gender. Humans have 23 pairs of chromosomes in each cell. A pair of chromosome forms the sex chromosomes. Males carry XY and females carry XX chromosomes. If a sperm carrying X fertilises the ovum with X chromosome, then theresulting baby isa girl. Ifa sperm carrying Y chromosome fertilises the ovum withX chromosome, then the resulting baby is a boy. Hence, males are responsible for the gender ofthe newly formed babies.

Reproductive Health: It is important to eat balanced food and maintain personal hygiene during adolescence. Cleaning of private parts is important to prevent possible infections. The activity of sweat glands increases in puberty and releases badodour from thebody. Thus frequent bathing is necessary. Physical exercise keeps the body fitand healthy asit releases lotof sweat. Peer pressure is best addressed by self-confidence anda healthy lifestyle.