Autonomic+Nervous+System

=Autonomic Nervous System=

The Autonomic Nervous System (otherwise knows as the visceral or involuntary nervous system) is the division of the nervous system responsible for automatic functions. This is basically the subconscious activity that keeps us alive. Some functions controlled by the autonomic nervous system include 1 :
 * Heart Beat
 * Salivation
 * Respiration
 * Digestion
 * Urination
 * Sexual Arousal
 * Pupil Dilation

The Autonomic Nervous System can be roughly divided into two parts: The sympathetic and parasympathetic nervous systems. The different between these two systems has been described as the difference between "Flight or Flight" and "Rest and Digest" 2

The Sympathetic Nervous System
The sympathetic nervous system is the bit that is responsible for the "Fight or Flight" response. If you need a rapid infusion of energy for immediate action (let's say that you are threatened or put in a high-stress situation) the sympathetic nervous system jumps into action. Your heartbeat is accelerated, your pupils dilate, you release adrenaline, your digestive system slows down, your mouth dries out and the bronchioles in your lungs expand. All of these responses are orchestrated to allow you to either fight or run for your life.

The Parasympathetic Nervous System
In contrast, the parasympathetic nervous system is used when you need to relax. You produce more saliva, your digestive system is kicked up, your heartbeat slows down. Your pupils constrict, and your liver produces more bile. =The link between the voluntary and involuntary nervous systems= Interestingly, it has been discovered that the autonomic nervous system can be stimulated by the voluntary nervous system. In a recent experiment it was shown that the stimulation of the voluntary nervous system by recreating specific facial expressions provoked an autonomic nervous system response (specifically in the emotional cortex)3. Basically, you can fool your brain into feeling better by 'faking it'. The link is not clearly understood, but it's an interesting idea. =References= Wikipedia Article: The Autonomic Nervous System Neuroscience for Kids: The Autonomic Nervous System Voluntary facial action generates emotion-speciﬁc autonomic nervous system activity