Background

The "fight or flight" response is a pattern of physiological changes in the body that help an organism (man or animal) deal with a threatening situation. For an animal, this situation could be a predator, and in order to survive or protect its young, the animal must either fight or run away. It will use all available resources to deal with the threat, and the inner balance of its body will change accordingly. This physical exertion helps to dissipate the stress hormones that are released in the animal's body.

For humans, life is more complex, and stress can take many different forms. The stress response in a true emergency (running away from a fire) is helpful and necessary to our survival.  Stress can also have positive influences such as compelling us to work harder, or giving us an exciting new perspective about something. Unfortunately, our bodies cannot distinguish between a serious threat and the stresses of everyday life.  We can't (and shouldn't) just get out of our cars in traffic and fight the driver who cut us off, and we cannot run away either. When the candy machine "eats" our dollar, we can't fight with it (although some people try), and fleeing leaves us with no candy and no dollar --both very unsatisfying outcomes.   In these examples, the stress response serves no purpose because we can't control what is happening. However, the body still secretes stress hormones, such as cortisol and adrenaline, to prepare us for the stressful situation. Since we didn't physically exert ourselves by fighting or running, we have not expended the energy necessary to dissipate these stress hormones coursing through our bodies. (This is why aerobic exercise is considered a good "stress-buster.")  So what’s the harm? The extended wear and tear on our bodies leads to distress.  High levels of the stress hormones remain, and over time, can lead to health imbalances.

Research has shown that there is a link between the immune system and stress.  When you are ill or injured, many different immune system cells stream to the location where they are needed. The cells send certain molecular signals to other cells and the brain, including the part of the brain that controls the stress response. For example, cortisol is released to help control inflammation, and plays a role in suppressing the immune system when the inflammation or infection is under control. If we are chronically stressed, high levels of stress hormones are still being released in the body, and the immune cells are being told that there is no need to do their jobs. They are less responsive to bacteria and other invaders that they should be fighting, and we tend to catch more colds or take longer to recover from illness.

Stress is largely about perception.  We may view something as a threat to our well-being, and then we think we cannot cope with the threat.  Although at times we really can't change what is happening, we can change the way we perceive it.  We can choose how we react. Our bodies are unable to distinguish between real or imagined stress.  Even remembering a scary movie or an unpleasant situation can invoke the physical changes of the fight or flight response.

What happens in our bodies when we encounter stress?

· Heart rate increases and pumps blood through the body faster, trying to provide oxygen and sugars to cells. 

· Stress hormones, primarily adrenaline (also called epinephrine), are released to help maintain the heart rate and signal the liver to release sugar so the body has extra energy.

· Blood pressure may rise because of the increase in stress hormones. 

· Blood supply is prioritized, and directed toward the major muscles and the parts of the brain governing motor skills and other basic functions. It moves away from the skin surface, which is a primitive response that saves us from bleeding to death when we are fighting or fleeing. The digestive and reproductive organs become a low priority, as do the parts of the brain that control thinking and speech.

· Senses sharpen so that we are more aware of our surroundings and can respond more quickly.

· Endorphins, which serve as natural painkillers, are released to provide defense against pain.

In addition to what we perceive as external stresses (traffic, taking tests, etc.), there is another type of stress that occurs inside the body.  If you rest your forearm and hand on a desk and raise your index finger, you should feel tightness across the top of your hand and into your forearm. Muscles are activated by signals from the brain, and work within the body by contracting, which is a different kind of stress than the type that elicits the fight or flight response.