The human nervous system and reflexes

• A reflex is an automatic and rapid action carried out by the body
• The three types of neurone are sensory, motor and relay neurones
• The pathway of electrical impulses for a reflex is receptor --> sensory neurone --> relay neurone --> motor neurone --> effector
• A synapse is a physical gap between two neurones
• When an electrical impulse reaches a synapse it causes the release of neurotransmitters which are received by the next neurone - starting an electrical impulse
• Sensory neurones are connected to receptors and carry impulses to the CNS (Central Nervous System)
• At the end of the sensory neurone there is a synapse which releases neurotransmitters that diffuse across to a relay neurone in the CNS
• After the electrical impulse passes across the relay neurone, it reaches a synapse which releases neurotransmitters that diffuse across to a motor neurone
• After the electrical impulse passes down the motor neurone, it goes to an effector which causes the response