NCERT Gist: Reaching The Age of Adolescence | Additional Study Material for UPSC PDF Download

- The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. The human body undergoes several changes during adolescence.
- These changes mark the onset of puberty. At puberty, the voice box or the larynx begins to grow.
- During puberty the secretion of sweat glands and sebaceous glands (oil glands) increases.
- A few glands such as sweat glands, oil glands and salivary glands release their secretions through ducts. Endocrine glands release hormones directly into the bloodstream.
- So, they are also termed ductless glands.
- The changes which occur at adolescence are controlled by hormones.
- Honnones are chemical substances.
- These are secretions from endocrine glands, or endocrine system.
- The male hormone or testosterone begins to be released by the testes at the onset of puberty.
- This causes changes in boys about which you have just learnt, for example, the growth of facial hair.
- Once puberty is reached in girls, ovaries begin to produce the female hormone or estrogen which makes the breasts develop.
- Milk secreting glands or mammary glands develop inside the breasts.
- The production of these hormones is under the control of another hormone secreted from an endocrine gland called pituitary gland.
- Endocrine glands release hormones into the bloodstream to reach a particular body part called target site.
- The target site responds to the hormone.
- There are many endocrine glands or ductless glands in the body.
- Thyroid and adrenals secrete their hormones when they receive orders from the pituitary through its hormones. Pituitary also secretes growth hormone which is necessary for the normal growth of a person.
- Adrenal glands secrete hormones which maintain the correct salt balance in the blood.
- Adrenals also produce the hormone adrenalin.
- It helps the body to adjust to stress when one is very angry, embarrassed or worried.
- Metamorphosis in insects is controlled by insect hormones. In a frog, it is controlled by thyroxine, the hormone produced by thyroid.
- Thyroxine production requires the presence of iodine in water.
- If the water in which the tadpoles are growing does not contain sufficient iodine, the tadpoles cannot become adults.