Automatic nerve function

Sympathetic Nervous System a network of nerves that trigger certain involuntary and automatic bodily functions, such as constricting blood vessels, widening the pupils, and speeding up the heartbeat. 

A particularly good example of how the working of the body is related to God s divine will is Boerhaave s discussion of the Aristotelian concept of sen-sorium commune in explaining the connection between the body and the mind as well as the connection of man to God. It is the place in the brain where all sense perception and impressions of the nerves come together and cause ideas, emotions, passions and voluntary motions. Boerhaave localised the sensorium commune in the place where all sensations originate, i.e. in all the points where the cerebral cortex and spinal marrow transfer into nerves. Boerhaave is very particular in stating that once the sensorium commune has set the body into motion it functions automatically, which means that for instance when someone decides to walk from Leiden to Amsterdam and back, the body will automatically do so. 

BIOFEEDBACK. This term refers to various techniques by which a limited amount of voluntary control is gained over certain body functions that were hitherto thought to be strictly automatic and therefore not subject to such control. It may be necessary for certain excitable people to learn how to exert control over their nerves so that they may prevent steep rises in blood pressure and/or racing of the heart when they become excited. Overreaction to emotional excitement, if habitual, could offset the benefits which accrue from the treatment of their disease. However, they may be taught how partially to control their blood pressure and heart rate by biofeedback, thereby countering the threat of various cardiovascular disorders. 

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