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PHYSICAL REACTIONS

Our internal organs are controlled and regulated, without our conscious effort, by the autonomic (or vegetative) nervous system (ANS). The ANS consists of two antagonistic sets of nerves, the sympathetic and the parasympathetic nervous systems. The former connects the internal organs to the brain by spinal nerves; it prepares the organism for fight or flight when stress occurs. The nerve fibres of the parasympathetic nervous system, on the other hand, consist of cranial nerves and lumbar spinal nerves and have the task of getting the body back to normal after it has been aroused by the sympathetic nervous system.

This means that the sympathetic nervous system, once it is aroused, will set in motion a number of physical processes such as general muscle tension, dilation of the pupils, restriction of the flow of saliva in the mouth, dilation of the bronchi, opening of the pores and increased perspiration, constriction of the bowels and loosening of the bladder. In addition, the liver is activated to release sugar into the blood to produce extra energy, and hormones such as adrenalin and corticosteroids are pumped out into the system, accelerating breathing and increasing the heart rate. While all this is going on the autonomic nervous system slows down digestion processes.

Once the stress-inducing situation is over, the parasympathetic branch of the nervous system reverses all the above processes – the pupils contract again, saliva starts flowing freely once more, the bronchi contract, the heart rate slows down, the pores close, the bladder contracts and digestion is stimulated, as is the release of bile which helps digest fats.

To help you understand these physical processes we will take a look at a typical situation that produces some common stress symptoms.

SITUATION

You are worried about having to give a talk in front of a group of people. As you prepare for it, you become aware of the following physical reactions in yourself:

– your mouth goes dry and your voice becomes more high-pitched (flow of saliva restricted, muscles in throat tense)

– your heart beats faster and your breathing becomes irregular (chest muscles tense up and bronchi dilate, adrenalin is released)

– you need to go to the toilet to pass water more often than usual (bladder loosened)

– you are constipated or have stomach cramps (muscles tense up)

– your hands feel clammy (pores open and perspiration increases)

– you feel anxious and have ‘butterflies’ in your stomach (adrenalin is pumping through your system)

– you feel restless and pace up and down, your hands shaking and your knees trembling (blood sugar levels are up to provide more energy; adrenalin and corticosteroids accelerate body processes).

As you can see, these physical symptoms are not all in the mind but are caused by very real changes in your blood chemistry, activated by the sympathetic nervous system. However, it is your mind that ultimately determines how strongly your body reacts to change or unusual circumstances. Depending on your attitudes, beliefs and general predisposition you will assess a situation as either harmless or dangerous. Some people positively thrive on challenges and are at their best when they need to deal with unforeseen situations; others will feel threatened and stressed.

The effects of the sympathetic nervous system can be very beneficial, provided they do not come into play too often or too excessively. A slight increase in body tension, together with higher energy levels and the associated faster reaction time, is of great value if you have to perform well; it is when these reactions become excessive that problems result and we are less likely to cope well.

When the sympathetic nervous system is stimulated repeatedly and over a long period of time, your body may be able to adapt for a while, but as soon as any additional demands are made on it – such as those brought about by an unhealthy diet, smoking, drinking or lack of sleep – your system gets overloaded and can break down. Being in physical overdrive can become a habit, and if there is never a chance for the parasympathetic nervous system to kick into gear and reverse the process, you wear down your inner organs. This is analogous to driving your car at high speed in a low gear all the time – eventually you have problems with the engine.