How does a reflex arc work?

A reflex arc is a system of sensory, motor and relay neurones that work together to provide a quick reaction to stimulus that protects us from danger. A really good example that often comes up in textbooks and exams is what happens when you touch a hot object.So what happens is the stimulus (That is the touching of the hot object.) is detected by the sensory receptors in your skin. This then produces and electric impulse which travels along your sensory neurone to the spinal cord. When the impulse reaches the synaptic cleft (The space separating the neurones at a nerve synapse.) it triggers the production of chemical messengers called neurotransmitters which carries the information to the relay neurone in the spinal cord.This sets off another electrical impulse which travels to the synapse between the relay neuron and the motor neurone again producing neurotransmitters to carry the impulse across the synaptic cleft and to the motor neurone. This produces yet another impulse which then travels down the motor neurone returning to the arm and reaching the effector organ which the contracts to move the hand away from the hot object. This movement is called the response.