Other physical symptoms include dizziness, nausea and other symptoms that reflect the body's "fight or flight" (controlled by the limbic system in the brain) response to danger. The muscles tense and the person feels they are literally going to die when faced with their fear. The host of physiological changes activated by the feared situation or object are caused by a chemical imbalance primarily in the amygdala, a part of the brain that helps control fear responses. Normally when someone is in a serene, unfearful state, the "firing" of the neurons in the amygdala is minimal. A feared stimulus, once perceived, is relayed from the sensory cortex of the brain through the thalamus to the brain itself. A more intense and prolonged discharge of the amygdala activates the sympathetic nervous system which leads to the release of norepinephrine from nerve endings serving the heart, lungs, blood vessels and other sites. (Lefton, L.A. 1997) .
A specific phobia is a marked and persistent fear that is excessive and unreasonable, cued by the presence or anticipation of a specific object or situation. Exposure to the phobic stimulus provokes an immediate anxiety response or panic attack. The person realizes that the fear is excessive and irrational and either avoids the situation (or object) or endures it with intense anxiety and distress. The avoidance, anxious anticipation and distress significantly interferes with the person's daily routine - occupational functioning and social activities. .
A person can develop a specific phobia of anything, but in most cases the phobia is shared by many and has a name. Animal phobias - cynophobia (dogs), equinophobia (horses), zoophobia (all animals) - are common. So are arachnophobia (spiders) and ophidophobia (snakes). And of course, there's the fear of flying (pterygophobia), heights (acrophobia), and confined spaces (claustrophobia). "One of the most common phobias is the fear of dentists (odontophobia), " says Sheryl Jackson, Ph.