The BBC describes a reflex arc as the nerve pathway through which neural impulses travel to cause a quick autonomic response known as a reflex. Reflexes are not something people think about, rather, they are impulsive reactions to stimuli.
An example illustrated by class notes from Rutgers University explains that when a person touches a flame or hot surface with his hand, his immediate reaction is to remove his hand from the heat to prevent getting burned. This decision, or reflex, is not a conscious one. In general, there are five parts of a reflex: receptor, the sense organ, such as skin muscle or another organ; sensory neuron, which is in charge of carrying the neural message to the central nervous system; interneuron, which carries the message within the central nervous system; motor neuron, which carries the impulse away from the central nervous system; and effector, the structure that reacts and exhibits a response.
According to Rutgers University, the reflex response can be more involved. For example, if a person steps on a sharp object, the reflex is to lift his foot off the object. There is also the stabilization of the other leg as he lifts his foot off the ground. This means this type of reflex response involves some consciousness.