​Autonomic nervous system (ANS)

Part of nervous system responsible for many functions in the body that occur "automatically"

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The actions of the ANS take place completely beyond our conscious control.

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​Examples: digestion, heart rate, blood pressure, and body temperature.

​Sympathetic nervous system (SNS)

​The part of the autonomic nervous system that responds to stressful situations by initiating the fight-or-flight response.

​Parasympathetic nervous system (PNS)

​The part of the autonomic nervous system that slows down body functions, activated when you relax or when SNS stimulated too long. Also called "rest and digest".

​Comparing the two systems

​When the sympathetic nervous system is engaged, your body is entirely focused on what will help you either fight or run away quickly.

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​Some body functions will change to better help you in the fight or flight response.

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​Other functions of your body that are not immediately needed stop or slow way down.