parasympathetic nervous system
Meaning of parasympathetic nervous system: The parasympathetic nervous system slows the heart and promotes digestion, largely opposing the body's fight or flight response.
Definition of parasympathetic nervous system
The parasympathetic nervous system is one of the two main divisions of the autonomic nervous system, the part of the nervous system that regulates involuntary body functions. It generally promotes rest and recovery, slowing the heart rate, constricting the pupils, stimulating digestive activity, and relaxing certain muscles, effects often summarized as supporting rest and digestion.
The parasympathetic nervous system works largely in opposition to the sympathetic nervous system, which prepares the body for activity or stress by increasing heart rate and redirecting blood flow toward muscles. Together, the two systems continuously balance the body's internal state according to its current needs, rather than one system simply switching off when the other is active.
Much of the parasympathetic nervous system's output travels through the vagus nerve, which extends from the brainstem to influence the heart, lungs, and digestive organs, making it central to how this division exerts its widespread effects throughout the body.
Used in a sentence
Vagal maneuvers were attempted to stimulate the parasympathetic nervous system and slow the patient's rapid heart rate.
Good to know
The parasympathetic and sympathetic nervous systems generally work in continuous balance rather than in simple opposition, so effects attributed to one system often reflect a shift in this balance rather than one system acting alone.
Word origin
Where “parasympathetic nervous system” comes from
Formed from Greek para-, meaning beside or alongside, combined with sympathetic, itself from Greek syn-, meaning together, and pathos, meaning feeling.