ANS

The autonomic nervous system ( ANS ) is part of the peripheral nervous system ( PNS ). It has an important function in maintaining the internal environment of the human body in a steady state. This role is vital in returning the body to a homeostatic state after trauma. As various changes occur within the environment, both internal and external, the ANS reacts by regulating such things as the Blood Pressure, Heart Rate, Concentration of salts in the Blood Stream etc.
For example when the level of nutrients within the blood stream falls, the Sensory Nervous System (SeNS ) picks this up and stimulates the ANS to activate food seeking behaviour and also stimulates the digestive processes. If the body becomes dehydrated such as playing football on a very hot cloudless day the SeNS will pick up sensory information on the depletion of body fluid and the ANS will activate the mechanisms which conserve and replenish body fluids.
The ANS is also involved in many other body activities such as, waste disposal, response to stress, and sexual response. The functions of the ANS underlie the physiological aspects of coping during stress and forms a major link between the nervous system and the endocrine system during these times. The system generally works automatically without voluntary control - hence the name which comes from ancient Greek meaning 'self governing'. We do not consciously direct the rate of our heart beating nor are we normally aware of the diameter of our blood vessels or the need to stimulate our salivary glands to produce saliva. However the effects of the ANS do impinge upon our consciousness, especially at times of heightened emotion. For example most of us have experienced fear, either real or imagined, at some time in our lives and have been aware of our hearts beating faster. The increased heart rate is due to the effects of the ANS.