Reflex arc

• 1. The stimulus is detected by a pain, pressure or touch receptor in the skin
• 2. A sensory neurone sends electrical impulses from the receptor to the spinal cord.
• 3. An electrical impulse is passed to a relay neurone in the spinal cord.
• 4. A relay neurone synapses with a motor neurone.
• 5. A motor neurone carries an impulse to an effector (either a muscle or gland).
• 6. The muscle/gland (the effector) will respond accordingly when stimulated by the motor neurone.
• An involuntary (or reflex) response in the reflex arc does not involve the conscious part of the brain as the coordinator of the reaction. Responses are automatic and rapid, which helps minimise damage to the body.