IGCSE Biology glossary
Reflex arc
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
The nerve pathway of a reflex action: receptor → sensory neurone → relay neurone (in the spinal cord) → motor neurone → effector, producing a fast, automatic response that protects the body.
What to include in an exam answer
Sequencing questions are marked on the correct order and correct neurone names. 'Fast' and 'automatic/does not involve conscious thought' are the two description marks. Drawing arrows the wrong way along neurones is an instant lost mark.
Example in context
Describing a hand pulling off a hot object: 'The receptor detects heat; the impulse passes along sensory → relay → motor neurones to the muscle, which contracts. A reflex arc.'
Related syllabus topic
Coordination & responseRelated terms
- Homeostasis
- Negative feedback
- Tropism
- 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
- Hormones
- Endocrine gland
- Auxin
- Thermoregulation
- Vasoconstriction
- Vasodilation
- Sweating