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Oct 30, 2023 · The parasympathetic nervous system (PSNS) is a division of the autonomic nervous system (ANS) that controls the activity of the smooth and cardiac muscles and glands. It works in synergy with the sympathetic nervous system (SNS), which complements the PSNS activity.
- Medical Content
- 22 min
- Overview
- Parasympathetic nervous system function
- Parasympathetic nervous system and your heart
- Parasympathetic cranial nerves
- Sympathetic and parasympathetic nervous system
- Examples of parasympathetic responses
- The takeaway
The parasympathetic nervous system (PSNS) is one of two major divisions of the larger autonomic system in your body. Its function is to keep the basic functions of your body working as they should.
Your nervous system is a wild and wonderful network of nerves that act in different key functions to keep your body moving, responding, sensing, and more.
The parasympathetic and sympathetic portions of the autonomic system are two halves of the same whole. This article will examine the parasympathetic nervous system, what it controls, and how it works with the sympathetic nervous system.
Parasympathetic nervous system definition
Doctors often call the parasympathetic nervous system the “rest and digest” side, while the sympathetic is the “fight or flight.”
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Your PSNS starts in your brain and extends out via long fibers that connect with special neurons near the organ they intend to act on. Once PSNS signals hit these neurons, they have a short distance to travel to their respective organs.
Examples of the areas the PSNS acts on include:
•eyes
•lacrimal glands that produce tears
•parotid glands that also produce saliva
•salivary glands that produce saliva
There are several special receptors for the PSNS in your heart called muscarinic receptors. These receptors inhibit sympathetic nervous system action. This means they’re responsible for helping you maintain your resting heart rate. For most people, the resting heart rate is between 60 and 100 beats per minute.
On the other hand, the sympathetic nervous system (SNS) increases heart rate. A faster heart rate (usually) pumps more oxygen-rich blood to the brain and lungs. This can give you the energy to run from an attacker or heighten your senses in another scary situation.
According to an article in the journal Circulation from the American Heart Association, a person’s resting heart rate can be one indicator of how well a person’s PSNS, specifically the vagus nerve, is working. This is usually only the case when a person doesn’t take medications that affect heart rate, like beta-blockers, or have medical conditions affecting the heart.
For example, heart failure reduces the response of the parasympathetic nervous system. The results can be an increased heart rate, which is the body’s way of trying to improve the amount of blood it pumps through the body.
The cranial nerves are paired nerves that are responsible for many movements and sensations that take place in your body’s head and neck. The nerves all start in the brain. There are 12 cranial nerves labeled using Roman numerals from I to XII, with the first set of nerves located at the brain’s front.
For the most part, if you know the actions of the PSNS, you can consider the sympathetic nervous system to have opposite reactions. However, there are times when the systems are opposites, but instead complement each other.
Here are some key differences in the two:
An easy acronym to remember how and where the PSNS works is SLUDD. This stands for:
•Salivation: As part of its rest-and-digest function, the PSNS stimulates production of saliva, which contains enzymes to help your food digest.
•Lacrimation: Lacrimation is a fancy word for making tears. Tears keep your eyes lubricated, preserving their delicate tissues.
•Urination: The PSNS contracts the bladder, which squeezes it so urine can come out.
•Digestion: The PSNS stimulates the release of saliva to promote digestion. It also enacts peristalsis, or the movement of the stomach and intestines, to digest food as well as release bile for the body to digest fats.
•Defecation: The PSNS constricts the sphincters in the intestine and moves digested food material down the digestive tract so a person can have a bowel movement.
Your PSNS is a vital part of your body’s key functions. When it doesn’t work properly, you can face several bodily dysfunctions that affect your health. If you think you may be having trouble with one of your body’s parasympathetic nervous system functions, talk with your doctor to find out how you can get help.
- Rachel Nall, MSN, CRNA
- Slower than the sympathetic division
Your parasympathetic nervous system is a key part of your body’s long-term survival. This system constantly works without you thinking about it, whether you’re asleep or awake. It helps relax you in times of calm and provides a balance with your body’s short-term survival responses.
Oct 31, 2022 · The parasympathetic nervous system (PNS) is 1 of the 2 functionally distinct and continuously active autonomic nervous system (ANS) divisions. It opposes the other, the sympathetic nervous system (SNS). The parasympathetic nervous system predominates in quiet “rest and digest” conditions.
- Jacob Tindle, Prasanna Tadi
- Asram Medical College, Eluru, India
- 2020
- 2022/10/31
Structure. The parasympathetic nerves are autonomic or visceral [6][7] branches of the peripheral nervous system (PNS). Parasympathetic nerve supply arises through three primary areas:
Mar 24, 2022 · Your breathing usually does not require any thought, because it is controlled by the autonomic nervous system, also called the involuntary nervous system. The parasympathetic system slows your breathing rate. It causes your bronchial tubes to narrow and the pulmonary blood vessels to widen.
Oct 20, 2023 · The parasympathetic nervous system is defined by the craniosacral origin of its nerve fibres, which come out of the brainstem and the S2-S4 sacral spinal cord segments. Preganglionic neurotransmission is nicotinic and postganglionic neurotransmission is muscarinic, both using acetylcholine.
