Difference Between Sympathetic and Parasympathetic Nervous System

​​​​​​​Introduction

In animals, the sympathetic and parasympathetic nervous systems are a part of the autonomic nervous system (ANS). The ANS regulates the body’s automatic or reflex actions, including the control of internal organ operations including those of the heart, stomach, and intestine. Under the peripheral nervous system is the self-regulating autonomic nervous system. To sustain vital biological processes, it essentially maintains the interior environment of the body by exchanging commands with the peripheral nervous system and organs. The autonomic nervous system is divided into two primary groups as well. They are the parasympathetic and sympathetic nervous systems, respectively. Even though both systems typically affect the same organ and produce the same action potentials, their roles are distinct and at odds with one another. The cranial, thoracic, and lumbar spinal cord areas are where the sympathetic nervous system gets its start. The spinal cord’s cranial and sacral portions are where the parasympathetic nervous system is born.

Sympathetic Nervous System vs. Parasympathetic Nervous System

An animal’s autonomic nervous system (ANS) includes the sympathetic and parasympathetic nervous systems. Internal organ functions, including those of the heart, stomach, and intestines, are regulated by the autonomic nervous system (ANS). The key distinction between the sympathetic and parasympathetic nervous systems is that the sympathetic nervous system is in charge of regulating how the body reacts to perceived danger and triggering the “fight-or-flight” response, whereas the parasympathetic nervous system is in charge of maintaining homeostasis and triggering the “rest-and-digest” response. Another major distinction between the sympathetic and parasympathetic nervous systems is that the former prepares the body for vigorous physical activity, whilst the latter relaxes the body by suppressing high-energy functions.

Difference Between Sympathetic and Parasympathetic Nervous Systems in Tabular Form

Parameters	Sympathetic Nervous System	Parasympathetic Nervous System
Meaning	One of the two primary divisions of the autonomic nervous system (ANS) is the sympathetic nervous system. Generally speaking, it activates the body’s fight-or-flight reaction.	One of the two primary divisions of the autonomic nervous system (ANS) is the parasympathetic nervous system. Controlling homeostasis and the body’s response to rest and digestion is its main purpose.
Function	Manage your body’s reaction to perceived threats.	When at rest, you can control how your body reacts.
Site of Origin of Fibers	The thoracolumbar division of the ANS is another for the sympathetic fibers that originate in the thoracic (T1) and Lumbar (L2/L3) spinal cord segments.	The oculomotor nerve, or third cranial nerve, the facial nerve, or seventh cranial nerve, the glossopharyngeal nerve, or ninth cranial nerve, and the vagus nerve, or tenth cranial nerve, are the origins of parasympathetic fibers.
Position of the Ganglions	Ganglions of the sympathetic nervous system can be found nearby the central nervous system.	Ganglions of the parasympathetic nervous system are positioned nearby the effector but distant from the central nervous system.
Post Ganglionic Nerve	Post-ganglionic Fibers are found abundant in the sympathetic nervous system.	The parasympathetic nervous system has few post-ganglionic fibers.
Mode of the Effect	A dispersed effect is produced at the target location by the sympathetic nervous system.	The parasympathetic nervous system causes a localized effect in the area it is intended to affect.
Realizing Neurotransmitter	The sympathetic nervous system causes noradrenaline to be released at the effector.	The Parasympathetic nervous system causes the effector to release acetylcholine.

What is Sympathetic Nervous System?

Part of the autonomic nervous system (ANS), the sympathetic nervous system keeps the body in a state of homeostasis by preparing it to react to stressful conditions. The spinal cord’s thoracic and lumbar areas are affected by it. The fight-or-flight reaction, often referred to as the sympathoadrenal response, is a neural and hormonal response to stress that is mediated by the SNS. Acetylcholine is released in response to pre-ganglionic sympathetic nerve fibers terminating at the adrenal medulla, activating adrenaline and noradrenaline. Adrenaline makes it easier to take quick physical activity to get the body ready for powerful muscular actions. Nearly all of the body’s organs are innervated by sympathetic nerve fibers. The heart rate, metabolic rate, and glycogen breakdown are all accelerated by efferent neural impulses, which also reduce the motility of the gastrointestinal tract and urine output. In addition, they enlarge the bronchial tubes, narrow the blood vessels, and enlarge the pupil of the eye. Sensations including heat, pressure, and pain are also transmitted via afferent neurons.

The body accelerates, tenses, and awakens with sympathetic nerve reactions. Functions that are not necessary for survival are shut down. The sympathetic nervous system can respond in the following ways:

• Increase in heart rate, heart muscle contraction, dilated bronchial tubes in the lungs, and dilated pupils in the eyes.
• Adrenaline is released from the adrenal gland.
• Contraction of muscles.
• For providing energy for the muscles, glycogen is converted to glucose.
• Functions that are not necessary for survival are shut down.
• Decrease in Saliva production: the stomach does not move for digestion, nor does it release digestive secretions.
• Decrease in urinary output.
• Contraction of sphincter.

You can benefit from these benefits when you need to move swiftly or think critically. They enhance your strength, stamina, endurance, and reflexes. When your body is under stress, such as when you are exercising or ill, your sympathetic nervous system also comes into play. Your immune system and your body’s repair mechanisms are both impacted by the activity of your sympathetic nervous system. If you get harmed, these effects may enable your body to begin healing the injury rapidly.

Because the sympathetic nervous system travels through very short neurons, the sympathetic nervous system is a quicker mechanism. When the system is turned on, the adrenal medulla is also turned on, causing it to release hormones and chemical receptors into the bloodstream. Activated muscles and glands in the target area. The parasympathetic nervous system takes control once the perceived threat has passed to balance the consequences of the sympathetic nervous system’s responses.

The Prevalent ailments and afflictions that impact the sympathetic nervous system

• Type 2 diabetes that is not under control might harm your sympathetic nervous system as well as your autonomic nervous system. Orthostatic hypotension, where your blood pressure lowers when you stand up, is an illustration of this. The nerves that typically cause blood pressure to raise reaction when you stand can be damaged by diabetes-related neuropathy.
• The sympathetic nervous system may become overworked by anxiety and persistent stress. That may eventually make you more susceptible to developing obesity and other metabolic issues.
• The adrenal glands, which are located on top of the kidneys, are a target of a particular type of cancer called pheochromocytomas. Neurotransmitters like adrenaline and norepinephrine are produced by your adrenal glands. These glands release an excessive amount of norepinephrine and adrenaline as a result of this type of cancer, which maintains your sympathetic nervous system functioning at an excessively high level.
• Sympathetic nervous system disorders like the genetic condition amyloidosis. A small portion of the sympathetic nerve connections in your face are affected by this disorder. This may result in drooping eyelids, a tiny pupil, and reduced face perspiration.

There is no single sort of treatment or strategy for diseases of the sympathetic nervous system, and treatments can take many various forms. Some of these could be as easy as taking medication or making lifestyle adjustments. Others might be trickier. Some therapies target the root of the issue, which could at least partially address the sympathetic nervous system issue. Treatments for a sickness that can’t be cured will probably concentrate on managing its symptoms and slowing its progression.

What is Parasympathetic Nervous System?

The ANS contains the parasympathetic nervous system (PSNS), which reduces the heart rate and relaxes the muscles. The spinal cord’s center is where the PSNS’s nerves begin. When compared to the sympathetic nervous system, the parasympathetic nervous system functions slower and acts differently than the sympathetic nervous system. Salivation, digestion, urine, lacrimation, and feces are all stimulated by the parasympathetic nervous system. The neurotransmitter involved in PSNS activities is acetylcholine. Acetylcholine is released when pre-ganglionic nerve fibers are stimulated, and this acetylcholine interacts with the post-ganglionic neurons’ nicotinic receptors. Acetylcholine is again released when post-ganglionic receptors are stimulated, and this acetylcholine interacts with the target organ’s muscarinic receptors.

To balance out the sympathetic nervous system, there is the parasympathetic nervous system. It brings the body’s condition of tranquility back. The particular responses are:

• The heart rate decreases.
• Constriction of bronchial tubes in the lungs and pupils in the eyes.
• Relaxation of muscles.
• Saliva production: the stomach moves and increases secretions for digestion.
• Increase in urinary output.
• Relaxation of sphincter.

Four of the 12 cranial nerves are used by the parasympathetic nervous system. These nerves have a direct line of communication with the brain. Three of those four only concern the glands and senses associated with your mouth, nose, and eyes. The fourth nerve, known as the vague nerve, attaches to a portion of the mouth and travels through the neck to the chest and abdomen. The vague nerve connects to the heart, lungs, and other crucial internal organs, constituting around 75% of your parasympathetic nervous system overall.

Similar portions of the nervous system can be found in the parasympathetic nervous system. The most common form of the cell is a neuron, which can send and receive signals.

The Prevalent ailments and afflictions that impact the parasympathetic nervous system

• The autonomic nervous system, which includes the parasympathetic nervous system, can be harmed if Type 2 diabetes is not under control.
• We are born with congenital and genetic conditions or diseases. Because we inherit them from either one or both of the parents, we have genetic disorders. Issues with the parasympathetic nervous system can result from inherited forms of amyloidosis.
• When the nerves that control the bladder and bowels are damaged, parasympathetic nervous system issues can lead to incontinence.
• Damage to the parasympathetic nervous system might cause erectile dysfunction in some people.
• Injury-related nerve damage has the potential to be long-lasting or even irreversible. This is particularly true if there have been spinal cord or major nervous system injuries that have impaired or severed parasympathetic connections farther down.

It can be difficult to treat diseases that impair the parasympathetic nervous system. That’s because, depending on what caused the issue in the first place, the therapies may differ significantly. Additionally, there are a variety of treatment options available, from medicine to surgery. Sometimes treating or resolving an underlying issue is necessary to treat a parasympathetic nervous system issue. When an illness cannot be cured, the aim is to treat it and lessen the severity of the symptoms.

The Main Difference Between Sympathetic and Parasympathetic Nervous Systems in Points

• The sympathetic nervous system responds swiftly when something happens. On the other hand, the parasympathetic nervous system responds slowly when activated.
• The sympathetic nervous system contains a significant number of post-ganglionic fibers. On the other hand, the parasympathetic nervous system contains a modest number of post-ganglionic fibers.
• The body’s sympathetic nervous system extends over a sizable portion. On the other hand, the target area of the parasympathetic nervous system experiences a localized effect.
• The sympathetic nervous system speeds up metabolism, blood pressure, and heart rate. On the other hand, the parasympathetic nervous system lowers blood pressure, metabolic rate, and heart rate.
• The sympathetic nervous system causes the effector to release noradrenaline. On the other hand, the parasympathetic nervous system releases acetylcholine at the effector.
• The digestive team is more active when there is a sympathetic nervous system. On the other hand, the digestive system’s activity is reduced by the parasympathetic nervous system.

Conclusion

In animals, autonomic nervous systems consist of two parts: the sympathetic and parasympathetic nervous systems. The spinal cord’s thoracic and lumbar regions are the source of the SNS, while the middle of the spinal cord is the source of the PSNS. The fight-or-flight response, which is triggered by stressful events, is prepared by the SNS. The PSNS, on the other hand, calms the body and controls its regular functions. Since they have an impact on how the body functions normally, the sympathetic and parasympathetic nervous systems are fundamentally different from one another.

References

• https://my.clevelandclinic.org/health/body/23266-parasympathetic-nervous-system-psns