Complex sentence: There are two autonomic nervous system (ANS) functions that occur when one recognises a life threatening situation, the sympatho-adrenal response of the sympathetic nervous system (fight or flight) are stimulated and the parasympathetic nervous system (rest and digest) slows down.
Split into simpler sentences: There are two autonomic nervous system (ANS) functions that occur when one recognises a life threatening situation. The sympatho-adrenal response of the sympathetic nervous system (fight or flight) are stimulated and the parasympathetic nervous system (rest and digest) slows down.