Sympathetic vs. Parasympathetic — What's the Difference?
By Tayyaba Rehman & Fiza Rafique — Updated on May 13, 2024
Sympathetic nervous system prepares the body for stress responses (fight or flight), whereas the parasympathetic nervous system promotes rest and digestion.
Difference Between Sympathetic and Parasympathetic
Table of Contents
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Key Differences
The sympathetic nervous system activates the body's rapid involuntary response to dangerous or stressful situations, by increasing heart rate and blood flow, whereas the parasympathetic nervous system helps to conserve energy by slowing down the heart rate and increasing intestinal and gland activity.
During a perceived threat, the sympathetic nervous system triggers adrenaline release and elevates alertness levels, on the other hand, the parasympathetic nervous system induces calming effects, promoting relaxation and recovery after stress.
Sympathetic responses are generally quick and short-lived, designed to mobilize the body's resources in emergency situations, whereas parasympathetic responses are slower and more prolonged, aimed at restoring the body to a state of calm.
Neurotransmitters play different roles in each system; the sympathetic nervous system primarily uses noradrenaline to activate its responses, while the parasympathetic system mainly uses acetylcholine to mediate its calming effects.
Anatomically, sympathetic nerve pathways originate from the thoracic and lumbar regions of the spinal cord, whereas parasympathetic pathways are associated with the brainstem and sacral spinal cord.
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Comparison Chart
Primary Functions
Prepares for fight or flight
Promotes rest and digestion
Activation
Quick response to stress
Gradual recovery post-stress
Key Neurotransmitters
Noradrenaline
Acetylcholine
Physiological Effects
Increases heart rate, expands airways
Decreases heart rate, stimulates digestion
Origin of Nerve Pathways
Thoracic and lumbar spinal cord
Brainstem and sacral spinal cord
Compare with Definitions
Sympathetic
Increases heart rate and blood pressure.
Sympathetic activation is why you feel your heart pounding under threat.
Parasympathetic
Slows the heart rate.
Parasympathetic influence is noticeable when you're relaxing and your heart rate drops.
Sympathetic
Expands airways to improve breathing.
Sympathetic responses include dilation of the bronchi.
Parasympathetic
Stimulates digestive processes.
After eating, the parasympathetic nervous system aids in digestion.
Sympathetic
Prepares muscles for exertion.
Sympathetic activity primes your muscles for a quick sprint.
Parasympathetic
Induces relaxation and energy conservation.
The parasympathetic system helps you unwind after a stressful day.
Sympathetic
Activates body's stress responses.
The sympathetic nervous system kicks in during a car accident.
Parasympathetic
Promotes gland secretion.
Parasympathetic activity increases saliva production during meals.
Sympathetic
Releases stored energy.
During exercise, the sympathetic nervous system mobilizes energy.
Parasympathetic
Helps in the maintenance of homeostasis.
The parasympathetic system maintains bodily functions during rest.
Sympathetic
Of, expressing, feeling, or resulting from sympathy
A sympathetic glance.
Parasympathetic
Of, relating to, or affecting the parasympathetic nervous system
Parasympathetic activity.
Parasympathetic agents.
Sympathetic
Favorably inclined
Not at all sympathetic to her proposal.
Parasympathetic
The parasympathetic nervous system.
Sympathetic
Agreeably suited to one's disposition or mood; congenial
Sympathetic surroundings.
Parasympathetic
Any of the nerves of this system.
Sympathetic
Easy to identify with and care about; likeable
A gloomy novel without a single sympathetic character.
Parasympathetic
Of or relating to the part of the autonomic nervous system that inhibits or opposes the effects of the sympathetic nervous system. It consists of nerves arising from the brain and the lower end of the spinal cord and supplying the internal organs, blood vessels, and glands.
Sympathetic
Of, relating to, or acting on the sympathetic nervous system
A sympathetic neuron.
Sympathetic stimulation.
Parasympathetic
(neuroanatomy) A parasympathetic nerve.
Sympathetic
Relating to or being vibrations, especially musical tones, produced in one body by energy from a nearby vibrating body and having the same frequency as the vibration of the nearby body.
Parasympathetic
(neurology) parasympathetic nervous system.
Sympathetic
Emitting such vibrations
Sympathetic strings.
Parasympathetic
Originates in the brain stem and lower part of the spinal cord; opposes physiological effects of the sympathetic nervous system: stimulates digestive secretions; slows the heart; constricts the pupils; dilates blood vessels
Sympathetic
Of, related to, feeling, showing, or characterized by sympathy.
John looked very upset. I gave him a sympathetic look.
Parasympathetic
Of or relating to the parasympathetic nervous system
Sympathetic
Showing approval of or favor towards an idea or action.
Sympathetic
Attracting the liking of others.
Sympathetic
(construction) Designed in a sensitive or appropriate way.
Sympathetic
(relational) Relating to, producing, or denoting an effect which arises through an affinity, interdependence, or mutual association.
Sympathetic magic is based on imitation or correspondence.
Sympathetic ink
Sympathetic
A supernatural connection or power resulting from two items having the same form or some other correspondence.
Sympathetic
(sound) Relating to musical tones produced by sympathetic vibration or to strings so tuned as to sound by sympathetic vibration.
Sympathetic
Relating to or denoting the part of the autonomic nervous system consisting of nerves arising from ganglia near the middle part of the spinal cord, supplying the internal organs, blood vessels, and glands, and balancing the action of the parasympathetic nerves.
Sympathetic innervation involves epinephrine.
Sympathetic
Inclined to sympathy; sympathizing.
Far wiser he, whose sympathetic mindExults in all the good of all mankind.
Sympathetic
Produced by, or expressive of, sympathy.
Ope the sacred source of sympathetic tears.
Sympathetic
Produced by sympathy; - applied particularly to symptoms or affections. See Sympathy.
Sympathetic
Of or relating to the sympathetic nervous system;
Sympathetic neurons
Sympathetic stimulation
Sympathetic
Expressing or feeling or resulting from sympathy or compassion or friendly fellow feelings; disposed toward;
Sympathetic to the students' cause
A sympathetic observer
A sympathetic gesture
Sympathetic
Having similar disposition and tastes;
A compatible married couple
With their many similar tastes, he found her a most sympathetic companion
Sympathetic
Showing or motivated by sympathy and understanding and generosity;
Was charitable in his opinions of others
Kindly criticism
A kindly act
Sympathetic words
A large-hearted mentor
Sympathetic
(of characters in literature or drama) evoking empathic or sympathetic feelings;
The sympathetic characters in the play
Sympathetic
Relating to vibrations that occur as a result of vibrations in a nearby body;
Sympathetic vibration
Common Curiosities
What happens when the sympathetic system is overactive?
It can lead to high stress, anxiety, and cardiovascular problems.
Why is the parasympathetic system called the 'rest and digest' system?
It conserves energy by slowing the heart rate and increasing intestinal activity.
What activates the sympathetic nervous system?
Triggered by stress, it prepares the body for a fight or flight response.
What neurotransmitter is associated with the parasympathetic system?
Acetylcholine is primarily used to mediate calming actions.
How do drugs that target these systems work?
They either mimic or inhibit neurotransmitters to enhance or suppress system-specific responses.
How does the parasympathetic nervous system help after eating?
It stimulates digestion and nutrient absorption.
Can the sympathetic and parasympathetic systems operate simultaneously?
Yes, but they typically have opposite effects to maintain balance.
Is the sympathetic nervous system always detrimental?
No, it's crucial for survival in emergency situations by enhancing readiness.
What physical signs indicate sympathetic activation?
Increased heart rate, sweating, and dilated pupils are common signs.
What effect does the parasympathetic system have on saliva production?
It increases production, facilitating digestion.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
Co-written by
Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
