What is the reflex arc and how does it protect us?

The reflex arc is a pathway that contorls a reflex action. Reflex actions are very fast (milliseconds fast) which can help in dangerous situations. For example, if I touch a hot pan, the reflex would be me withdrawing my hand very quickly so I don't get burnt. 

The pathway of a reflex involves some complicated terms and ideas that you need to know as they may come up in the exam. The pathway of information is as follows: 

stimulus--> receptor-->sensory neuron-->central nervous system --> motor neuron-->effector muscle-->response. 

I'll explain these terms in more detail as the unit progresses,