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Biology · Paper 2 · Foundation + Higher · B5

Hormones and endocrine glands

Key ideas1 of 3

Chemical messages in the blood

Endocrine glands secrete hormones directly into the bloodstream. Blood carries them around the body. A target organ responds to a particular hormone. Compared with nervous responses, hormonal effects are generally slower and longer lasting.

An endocrine gland secretes hormone molecules into the bloodstream. They reach a target cell and bind matching receptors.

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Daily 5 · Exam practice · Revision sheet ↓

Foundation + Higher · B5. Nine core lessons, followed by four labelled Higher Tier lessons.

AQA Combined Science Trilogy 8464 · 4.5.3.1. Original notes, questions and diagrams. Models are simplified; teaching data are illustrative.