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Patrick Kelly BA(Hons.) Counselling and Psychotherapy

Oranmore Counselling Centre




In this essay I will be discussing the effects that the Autonomic Nervous System has on various organs in the body. 

First of all let us examine briefly the background to the flight or fight response. We have inherited a set of biochemical systems to deal with stressful and potentially dangerous situations from our ancestors. Chemicals are released to enhance our muscle capacity to respond to a dangerous situation by either fighting or running away. This response was a saviour to our ancestors but because of our developed social mores this ‘emergency response’ is not as useful today. In brief when we perceive a problem, imaginary or real, the cerebral cortex sends an alarm to the hypothalamus, which subsequently stimulates the sympathetic nervous system to alter certain functions in our bodies. If the fight or flight response continues to go unchecked during periods of stress this can lead to negative long term effects as your body will produce corticoids, which can lead to inhibited functioning of the digestive system, reproduction, growth, tissue repair and the responses of the immune and inflammatory systems. Research into this area is producing evidence that the prevalence of some of our modern diseases can be as a result of chronic stress. The body has a natural “off switch” to stop the alarm messages being sent once the perceived danger has past. The fight or flight response becomes extinct and everything returns to normal via the parasympathetic nervous system (Davis, M., Robbins Eshelman. & McKay, M. 2000).

Now let us look in more detail at the effects of the Sympathetic stimulation on the Autonomic Nervous system. As we have outlined above in a perceived potentially dangerous situation the Sympathetic System changes the normal functioning of some of our organs. It also increases blood sugar and blood flow to the large muscle groups and organs necessary to deal with a flight or fight situation such as the heart, lungs, quadriceps, and biceps. All these put the body into high gear so once we perceive an impending stressful situation the stress response occurs within a split second. 

These are the individual organ responses to the Sympathetic stimulation:

Iris: Our pupils dilate to improve focus.tear ducts: Production of tears is halted so we can see clearly.

Sweat glands: Stimulated to secrete excess waste products. Therefore we begin to sweat.

Arteries: Arteries to the periphery contract increasing blood flow to the large skeletal muscles, heart and lungs. This results in us going pale and a cold feeling in the extremities.

Skin: External skin hair straightens to trap air to keep the body warm, which leads to more effective large muscles for running or fighting. We have often heard the expression ‘My hair stood on end’ used when people express fright or shock.

Heart: Heart is stimulated to increase blood flow. This can result in palpitations and you feel your heart racing. This can be measured by your increased pulse rate. Continued exposure to stress can lead to heart problems. Lungs: We unconsciously breathe very quickly taking shallow and fast breaths, this can give one the feeling of breathlessness. This allows us to take in more oxygen to supply the large muscles that aid in fight or flight. Prolonged exposure to stress can lead to breathlessness and exacerbation of respiratory conditions such as asthma.

Digestive System: The digestive system is shut down to conserve energy and to divert blood to the large muscle groups. The outward expression of this is a dry mouth feeling. Long term effects include indigestion, fluctuating weight, IBS and ulcers.

Adrenal glands: Stimulates the secretion of stress hormones (corticoids) such as adrenalin noradrenalin.

Bladder: The muscles in the bladder tighten to inhibit you from urinating. .

Anus: The muscles around the anus tighten to inhibit bowel movements. Long term effects of stress may include diarrhoea and constipation.

Sex organs: Blood flow to the sex organs is decreased and secretions of all glands are decreased leading to a lack of sexual sensation. 

Prolonged exposure to perceived stressful situations can have grave side effects. Therefore it is necessary to invoke the actions of the parasympathetic system, through the relaxation response, to deal with stress on a regular basis.

The parasympathetic system is the part of the autonomic nervous system that shuts down the stress response i.e. it controls the relaxation response. Red alert status is on stand down and everything returns to normal. Unlike the sympathetic system, which reacts in a split second, the parasympathetic system takes 15 – 20 minutes to relax you once the perceived threat is extinguished. These are the effects on the individual organs in the body once the parasympathetic system has engaged:Iris:

The pupils narrow.Tear ducts: Tear ducts are stimulated leading to moist bright eyes.

Sweat Glands: Sweat production is halted resulting in comfortably dry skin.

Arteries: The arteries dilate resulting in a good healthy colour.Skin: The hair looses the bristle effect resulting in smooth skin.

Heart: The heart slows down. No more palpitations or racing resulting in a slower pulse.

Lungs: Breathing becomes slower and deeper.

Digestive System: Secretion begins in the digestive glands. The gut muscles start to work again. This results in salivation.

Adrenal glands: Secretion of stress hormones is inhibited.

Bladder: Bladder muscles relax again resulting in an open bladder.

Anus: Muscles around the anus unclench.

Sex organs: Blood flow is increased to the sex organs, gland activity is increased resulting in increased sexual sensation.

In western thought it has generally been assumed that the Autonomic Nervous System is beyond our conscious control. However eastern philosophies such as Zen, Mindfulness and yoga would purport that through relaxation we can heal the negative effects of stress on our bodies, by invoking the actions of the parasympathetic system. Over the last fifty years it has become more evident that this is the case (Davis, M. et al. 2000).

I find a variety of techniques useful to bring on the relaxation response. I find breathing techniques very good and a quick method to diffuse stress. However for a full relaxation response I have recently started using Autogenic Training. I find AT particularly useful because you can bring it about through simple repeating to yourself without the use of outside stimuli such as CDs, outside voices etc. The formulae are particularly easy to memorise. 

Before one can attempt any relaxation technique there are certain criteria one should have in place. You need a quiet environment. This is necessary to help you concentrate and eliminate outside distractions. One needs something to concentrate on. In AT the constant repetition of your own inner voice is the concentration device. You need to maintain a passive attitude as concentrating on not doing the exercise right will act as a distraction. Finally a comfortable position is necessary to aid relaxation. I usually practice AT by lying on a yoga mat with my head supported by a pillow.

Autogenic Training is a form of self induced hypnosis. It involves relaxing in one of three positions and concentrating passively on verbal formulae that suggest warmth and heaviness, which bring on the relaxation response in the striped muscles in the body. There is no need to repeat out loud, the formulae are repeated in your head only. By use of further formulae the relaxation response is brought about in the cardiac system; the respiratory system; the abdominal region and also one can reduce blood flow to the head. (Davis et al 2000). 

Autogenic training is just one of an array of stress reducing techniques. There are a lot of helpful books on the subject of stress and of course there is always the option of seeking professional advice on reducing stress and learning progressive relaxation. 

The use of a stress diary can be used to monitor stress levels and keep a written record of feelings of stress. This can improve your awareness of stress. One can look back through a stress diary and pinpoint the reasons why for instance you might have a cold that you cannot shake off. Sometimes instances like this can happen due to a build up of stress. Through the use of a diary one can actively eradicate some of the sources of stress and actively seek more positive activities to replace them. 


Davis, M., Robbins Eshelman, E. & McKay, M. (2000). The relaxation & stress reduction workbook. Oakland CA: New Harbringer Publications.

Fishbein. (1978). Illustrated medical and health encyclopedia. Westport CT: H.S.

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