Hormone

noun (countable)

/ˈhɔːməʊn/

A hormone is a chemical signalling molecule secreted by endocrine glands or specialised cells directly into the bloodstream that travels to target tissues and organs where it elicits a specific physiological response by binding to receptor proteins. Major classes include peptide hormones (insulin, glucagon), steroid hormones (cortisol, oestrogen, testosterone, aldosterone), and amino-acid derivatives (thyroxine, adrenaline). India's National Programme for Control of Blindness and Visual Impairment and the National Iodine Deficiency Disorders Control Programme address iodine-deficient thyroid hormone synthesis — a condition affecting an estimated 350 million Indians in iodine-deficient zones.

✍️ Usage in a UPSC answer

India's mandatory iodisation of salt under the Iodine Deficiency Disorders Control Programme ensures adequate synthesis of thyroid hormones in populations inhabiting the sub-Himalayan goitre belt, where endemic iodine deficiency historically caused cretinism and intellectual disability.

Synonyms

chemical messengerendocrine secretionsignalling moleculeautocrine/paracrine factor (by signalling range)

Antonyms

neurotransmitter (local signalling)exocrine secretionenzyme (catalytic not signalling)

🌱 Word Family

hormonal (adjective), hormonally (adverb), endocrine (adjective/noun — hormone-releasing), phytohormone (noun — plant hormone), neurohormone (noun)

🔡 Root

Greek hormān = to urge on, to set in motion; from hormē = onset, impulse

📜 Etymology

The term was coined by British physiologists William Bayliss and Ernest Starling in 1905 (first proposed by Starling in a Croonian Lecture) from Greek hormān (to excite, to set in motion), the present participle form of hormē (impulse, onset). Bayliss and Starling had discovered secretin, the first identified hormone, in 1902. The Greek root hormē is cognate with 'hormone' in all European languages and also underlies the word 'orm' in some biological contexts.

🧠 Memory Hook

Hormone comes from Greek hormān = to urge on — a hormone is a chemical 'urger' that races through the blood to tell distant organs what to do. Picture a tiny chemical courier on a motorbike (hormān = set in motion), delivering urgent orders from one gland to a faraway organ.

📝 Seen in UPSC Question Papers

Prelims 2020 — Biotechnology

Real UPSC previous-year questions whose text uses “Hormone” — proof this word earns its place on your list.

⚗️ General Science 📖 Seen in: Human Body Systems — Organ Systems, Ph...

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