-When a finger touches a hot object, the stimulus/ heat is detected by temperature/ thermoreceptors in the skin/ dermis; An impulse is generated; which is transmitted along the sensory neurone; to the grey matter/ central nervous system/ spinal cord; The chemical transmission of impulse is done across a synapse; to relay neurone; and through another synapse; to motor neurone; and across another synapse; to muscles/ effectors/ biceps muscles; the biceps muscles contract and the hand is withdrawn;