The sympathetic nervous system is responsible for our response to stress, referred to as the "fight or flight" response. While the sympathetic nervous system is in full effect, the parasympathetic nervous system shuts down. The parasympathetic nervous system is responsible for body processes such as urination, digestion, and defecation. However, when exposed to stress, the parasympathetic nervous system is no longer controlling physiological processes that it would normally control when the body is in its normal, relaxed state. Hence, because the parasympathetic nervous system is no longer functioning, our ability to carry out certain physiological activities is impaired. Digestion, bowel movements, and hormonal secretions are altered. I hope I explained this well.