Ch 10 covers the changes that happen during adolescence — physical, emotional, and hormonal. Students learn about puberty, the endocrine system, and the importance of reproductive health.
Adolescence: the period from about 11 to 19 years. Puberty is the onset of sexual maturity. Changes: increase in height, change in body shape, voice change (boys), development of secondary sexual characters, hormonal changes, emotional changes.
Hormones are chemical substances produced by endocrine glands. Pituitary gland: master gland, controls other glands. Thyroid: produces thyroxine (regulates metabolism). Adrenal: produces adrenaline (fight-or-flight). Pancreas: insulin (regulates blood sugar). Sex hormones: testosterone (male), oestrogen (female).
Download: https://ncert.nic.in/textbook/pdf/hesc110.pdf | Complete book: https://ncert.nic.in/textbook/pdf/hesc1ps.zip
Sex is determined by sex chromosomes. Females have XX and males have XY chromosomes. The egg always carries an X chromosome, while sperm can carry either X or Y. If X-carrying sperm fertilises the egg → girl (XX); if Y-carrying sperm → boy (XY). The father's sperm determines the sex.
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