Question

explain sensory, motor n relay neurone

Answer 1

Sensory neurons are found in receptors such as the eyes, ears, tongue and skin, and carry nerve impulses from these parts to the spinal cord and brain. 
Relay neurons are found between sensory input and motor in the brain and spinal cord and allow sensory and motor neurons to communicate.
Motor neurons are found in the central nervous system and control muscle movements. When motor neurons are stimulated they release neurotransmitters that bind to the receptors on muscles to trigger a response, which lead to movement.