Involuntary response - automatic reflex to protect body from damage. A reflex brough about by a chain of nerves is called a reflex arc, where the sensory goes to the spinal cord, across a synapse by a relay neurone and to the motor.
Voluntary response - Brain is part of the response pathway.
Stimuli are changes in the environment that cause a response.
The pathway for a voluntary response is:
Stimulus -> Receptor -> Sensory -> CNS -> Motor -> Effector -> Response
Nerve impulses are sent the the effectors e.g. muscles.
Neurotransmitters are chemical messengers that carry information across a synapse- a gap between neurone fibres.
The myelin sheath is a fatty substance surronding dendrons (fibre that carries impulse) and axons (sends impulse to dendrites) that speeds up nerve imuplses.