Grade 12 · Biology
Hormones & glands
Why it matters
Chemical messengers.
Advanced20m readingPrerequisite: None
What are hormones?
Short answer
Hormones are chemical messengers secreted by endocrine glands directly into the bloodstream, which carries them to target cells elsewhere in the body. Only cells with the matching receptor respond, so a hormone can act on specific tissues far from its source. Hormones regulate slow, sustained processes such as growth, metabolism, and reproduction.
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Frequently asked questions
- How do hormones differ from nerve signals?
- Hormones travel in the blood and act slowly but with lasting effects; nerve impulses are fast and short-lived.
- Why does a hormone affect only certain cells?
- Only target cells carry the specific receptor that the hormone binds to, so only they respond.