Hormone
- ICSE Class 10, Unit 3 Human Anatomy and Physiology
A hormone is a chemical made by an endocrine gland and carried by the blood to a target organ, whose work it controls.
Endocrine glands have no ducts, or tubes. They pour their hormones straight into the blood. The blood carries each hormone all over the body, but only its target organ responds. A tiny amount is enough.
Exocrine glands are different: they send their juices out through a duct. A sweat gland is one. The pancreas is both: its ducts carry digestive juice, and its islet cells release insulin into the blood.
- Pituitary: growth hormone, and hormones that control other glands.
- Thyroid: thyroxine, which sets the pace at which the body uses food.
- Adrenal: adrenaline, for emergencies.
- Pancreas: insulin and glucagon, which keep blood sugar steady.
A small example
After you eat sweets, sugar in your blood rises. The pancreas releases insulin into the blood. The insulin reaches the liver and muscles, which take up the sugar. Your blood sugar falls back.
Where marks go
The 2024 ICSE Biology paper asked candidates to define a hormone, for 1 mark. The marking scheme in CISCE's 2024 Biology report has three parts: made by endocrine glands, carried by blood, acting on target organs. Examiners note answers that left out the gland or the blood.
The 2027 specimen paper asks candidates to explain the term, for 2 marks. Its draft marking scheme uses the same three ideas. Learn the definition with its key words. See value points.
Sources
Facts last checked against these sources on 30 September 2026.
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