IGCSE Biology glossary
Hormones
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
Chemical substances produced by endocrine glands and transported in the blood to target organs where they produce a specific effect. Hormones are slower-acting but longer-lasting than nerve impulses. Examples include insulin, adrenaline, oestrogen and testosterone.
What to include in an exam answer
Compare hormonal and nervous control: hormones travel in the blood (slower), have a widespread and long-lasting effect; nerve impulses travel along neurones (faster), have a precise and short-lived effect. This comparison is a common exam question.
Example in context
State two differences between hormonal and nervous communication (2 marks): Hormones travel in the blood and have a slow, long-lasting, widespread effect. Nerve impulses travel along neurones and have a fast, short-lived, precise effect.
Related syllabus topic
Coordination & responseRelated terms
- Homeostasis
- Negative feedback
- Tropism
- Reflex arc
- ADH
- Insulin
- Glucagon
- Adrenaline
- Synapse
- Neurone
- Sensory neurone
- Motor neurone
- Relay neurone
- Receptor
- Effector
- Cornea
- Iris
- Lens
- Retina
- Optic nerve
- Accommodation
- Type 1 diabetes
- Type 2 diabetes
- Endocrine gland
- Auxin
- Thermoregulation
- Vasoconstriction
- Vasodilation
- Sweating