Stress response is a direct individual reaction to a specific event or object, while a person is consciously aware of that event or object. For example, most people experience fear if someone points a loaded gun at them or if they see a tornado forming on the horizon. They also recognize that they are afraid, and what they are afraid of. It helps a person respond appropriately to real danger, (e. g., escape from dangerous place or situation). A typical example of the stress response is when a zebra sees a lion closing in for the kill: zebra’s stress response is activated and the animal is trying to escape. The escape requires intense muscular effort, supported by all of the body’s systems.

In humans there are two types of response evolved: fight or flight. Fight is manifested in aggressive, combative behavior; flight is manifested by fleeing potentially threatening situations. Fight and flight responses can assume wide range of manifestations, such as angry, argumentative behavior, as well as social withdrawal, substance abuse, and even television viewing. Behaviorally, the fight or flight response describes men’s reactions to stressful situations better than women’s, meaning that men are more likely to cope with stress via social withdrawal, substance abuse, and aggression. Some researchers believe that these aspects of the fight or flight response in men contributes to their earlier mortality, relatively to women’s. Women are more likely to cope with stress through social support, that is, by turning to others to both give and receive instrumental and emotional aid. This pattern of responding has been called “tend and befriend,” and refers to the fact that during stressful times, women are especially likely to show protective responses toward their offspring and affiliate with others for shared social responses to threat.

Anxiety, on the other hand, is often an unfocused, vague feeling, that one hardly can pin down to a specific cause of this very unpleasant condition. Anxiety is often triggered by objects or events that are unique and specific to an individual. Anxiety affects people of all ages and social backgrounds. The term for persistent anxiety that affects a person in day-to-day life is "anxiety disorder". A small amount of anxiety is normal in the developing child, especially among adolescents and teens. Anxiety is often a realistic response to new roles and responsibilities, as well as to sexuality and identity development. The pathophysiology of anxiety is not well understood.

There are several theoretical models exist. According to one of them patients with panic disorder have a faulty central “suffocation alarm” mechanism, and respond to slight rises in CO2 blood levels with a sensation of suffocation, and hence, panic. Evidence supporting this model includes the observation, confirmed in a number of studies, that panic attacks can be induced in susceptible individuals (though not in normal controls) by the intravenous infusion of sodium lactate or the inhalation of five percent CO2. A psychological theory of panic disorder postulates that panic attacks are the result of “catastrophizing” misinterpretations of bodily sensations.

Causes of anxiety

Coping with illness Having a serious physical illness, such as cancer, can make you anxious. Worrying about the implications of your diagnosis and possible treatment can become excessive and overwhelming.

Stress A buildup of stressful life situations may trigger excessive anxiety. For example, a combination of having a physical illness along with the stress caused by fear to lose work or pay may lead to generalized anxiety disorder.

Personality People with some personality types are more prone to anxiety disorders. People with unmet psychological needs, such as having a close relationship that isn't fulfilling, may feel less secure and be more at risk of any type of anxiety disorder.

Heredity Anxiety disorders appear to run in some families.

Gender Anxiety disorders are more frequent in women and developing in early age, although treatment may be delayed for years. Anxiety symptoms may be so impairing, that suffering people may receive disability. Most often anxiety treated by primary care physicians instead of psychiatrists, often, without an accurate diagnosis or adequate treatment.

Anxiety as a medical problem

Anxiety is one of the most common psychiatric complaints and anxiety disorders are commonly seen in primary care settings. Many studies have found prevalence rates of all DSM-IV anxiety disorders in primary care settings to range from 5 % to 21%. Anxiety is characterized by the following symptoms: