Our body reacts to anxiety with a number of physiological responses. Our heart rate is increased, our blood pressure rises, blood is diverted from the organs to the muscles, and the pupils of our eyes are dilated. The body prepares us to meet some emergency. It is really a preparation for action—for fight or flight. This response is a biologically ancient form of reaction, which we have inherited from times past when dangers were usually in the form of some threat of physical attack. The body’s physiological response is well adapted to meet such a threat.
But the warning of anxiety refers to a threat from within—all is not well in our mind. And the body’s traditional response to threats is of little help in this relatively new biological situation. In fact, the beating of our heart and the tensing of our muscles for physical action only tends to increase our anxiety, because there is no outward foe on whom we can vent the physical strength which has been mobilized. In other words our body responds to anxiety according to a biologically outmoded pattern of reaction which can neither rectify the cause nor help us tolerate the discomfort of our anxiety.
The general response of the body to anxiety is modified by a physiological self-regulation device. There are many such self-regulating mechanisms in the body—for instance those which control our body temperature, water balance, and the chemical constituents of the blood. The alerting response which prepares us for action by increasing our heart rate and raising our blood pressure is mediated through the sympathetic nervous system. When this system becomes too active, a self-regulating mechanism calls the parasympathetic system into activity to balance the effect of the overactive sympathetic system. But one of the main functions of the parasympathetic is to increase the mobility of the bowels and the contraction of the bladder. So anxiety in this indirect way may come to cause diarrhoea or frequent urination. This, of course, has quite the opposite effect of the primary response to anxiety, which was to mobilize our bodily resources in preparation for action.
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