Students should be able to explain how the structure of the nervous system is adapted to its functions. • The nervous system enables humans to react to their surroundings and to coordinate their behaviour. • Information from receptors passes along cells (neurones) as electrical impulses to the central nervous system (CNS). The CNS is the brain and spinal cord. The CNS coordinates the response of effectors which may be muscles contracting or glands secreting hormones. stimulus -> receptor -> coordinator -> effector -> response. • Students should be able to explain how the various structures in a reflex arc - including the sensory neurone, synapse, relay neurone and motor neurone - relate to their function. Students should understand why reflex actions are important. • Reflex actions are automatic and rapid; they do not involve the conscious part of the brain.