the nerve pathway linking the heat receptor in the hand with the arm muscle is about 1.5 meters in length. it would take the nervous impulse 0.02 seconds to travel this distance along a neurone. however it takes about 0.5 seconds for the arm to start moving during the reflex response to the heat stimulus.
It takes the muscle time to act once it receives a response from the nerves. It also takes time for the electric impulse to pass between gaps in the nerves (synapses).
