Introduction
To know the difference between sympathetic and parasympathetic nervous systems, let’s first look at their definitions.
What is a Sympathetic Nervous System?
It is the division of the autonomic nervous system which prepares the body for stressful situations and is located near the lumbar and thoracic regions in the spinal cord. A small amount of sympathetic nervous system activity can regulate vital body functions by stimulating the body’s fight or flight response. It responds as a physiological reaction by perceiving a threat or attack to survival. A few examples are regulating the rate of respiration, heart rate and pupillary responses.
What is a Parasympathetic Nervous System?
It is one of the divisions of the autonomic nervous system also known as the rest and digest system. It conserves energy when the body is relaxed, feeding or resting. Situated between the spinal cord and the medulla, it slows the heart rate, increases gland and intestinal activity in the gastrointestinal tract. Parasympathetic nervous system activities are essential for the overall functioning of the body as restoring the body’s nervous system is important to further function at the optimal level.
The Autonomic Nervous System
Often abbreviated as ANS, the Autonomic Nervous System is the part of our nervous system that supplies nerve endings in the blood vessels, intestines, heart, smooth muscles and glands. It is responsible to govern the involuntary functioning of all these body systems without a person’s conscious effort. When ANS doesn't function properly, disorders may arise leading to affected body parts or processes, which are often progressive. However, some of the autonomic nervous system disorders can be reversed.
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What is Sympathetic and Parasympathetic?
As defined above, the two main divisions of Autonomic Nervous System (ANS) are:
Sympathetic ANS
Parasympathetic ANS
Functions of the Autonomic Nervous System
The functions of the autonomic nervous system in the body processes can be listed as follows-
Blood pressure
Body temperature
Heart and breathing rates
Digestion
Metabolism and body weight
Keeping a balance of water and electrolytes like Na (Sodium) and Ca (Calcium)
Production of body fluids such as saliva, tears, and sweat
Defecation
Urination
Sexual response
How does the Autonomic Nervous System work?
When the ANS receives information about the external environment and the body, it responds by stimulating varied body processes, through the sympathetic nervous system, or can also inhibit the body systems through the parasympathetic nervous system. There are two nerve cells in an autonomic nerve pathway, one cell is situated in the brain stem region or spinal cord connected by nerve fibers to the rest of the cells. It is located as a cluster of nerve cells called autonomic ganglia from where the nerve fibers connect with internal organs.
Most of the ganglia for sympathetic division are situated just outside the spinal cord on both sides of it, whereas for parasympathetic ANS, these are located nearby organs where they are connected. Mostly, organs are controlled primarily by one of them, either sympathetic ANS or the parasympathetic ANS. In a few cases, the two nervous systems have opposite effects on the same organ. The sympathetic nervous system function is opposite to that of parasympathetic nervous system function. One of the best examples is increased blood pressure due to sympathetic division and decreased blood pressure due to the parasympathetic division. However, when both work in coordination, it is ensured to have a balanced situation according to different situations.
Difference between Sympathetic and Parasympathetic ANS
Let’s discuss the Differences between the Sympathetic and Parasympathetic Nervous System in a Tabular Form-
Acetylcholine
Acetylcholine is a neurotransmitter that works for both the central nervous system and the peripheral nervous system. Acetylcholine activates muscles in the peripheral nervous system and it also acts as an important neurotransmitter in the autonomic nervous system. Acetylcholine and its neurons form the cholinergic system in the central nervous system.
Acetylcholine is secreted at all pre and post ganglionic parasympathetic neurons, some postganglionic sympathetic fibers, all preganglionic sympathetic neurons, and in the pseudo motor neurons to sweat glands.
Acetylcholine produces a wide variety of effects in the central nervous system. It acts as a neuromodulator for arousal, plasticity, and reward. It also helps in the enhancement of sensory perceptions when we wake up.
Conclusion
Both the sympathetic and parasympathetic nervous systems comprise the autonomic nervous system. In response to a perceived threat, the sympathetic nervous system activates the fight or flight response, while the parasympathetic nervous system restores the body to a state of calm.
FAQs on Difference between Sympathetic and Parasympathetic Nervous System
1.Is there a major difference between the parasympathetic and sympathetic nervous systems?
In addition to providing the body with calm and stability, the parasympathetic nervous system prevents overworking. During a fight or flight response, the sympathetic nervous system gets involved.
2.What hormones are released by the sympathetic and parasympathetic nervous systems?
A heartbeat is accelerated when epinephrine and norepinephrine are released by the sympathetic nervous system.
Acetylcholine, a hormone that slows down the heart rate, is released by the parasympathetic nervous system.
3.What components make up the sympathetic and parasympathetic nervous systems?
Neurons in the parasympathetic nervous system are found in the brain and spine. The sympathetic nervous system consists of cells located within the gray column of the spinal cord.
4.What is an example of a sympathetic reaction?
It causes the heart to beat faster, expand bronchial passageways, decrease large intestine motility, constrict blood vessels, increase esophageal peristalsis, cause pupils to dilate, goosebumps and perspiration (sweating), and increase blood pressure.
5.Breathing is sympathetic or parasympathetic?
Our parasympathetic nervous system is triggered by deep breathing that is slow and steady. Our stress responses can also be managed by taking long, deep breaths that help reduce anxiety, fear, fast heartbeats, and shallow chest breathing.
6. What is an Autonomous Nervous System?
An autonomous nervous system consists of neurons in the peripheral nervous system that perform specific functions. These neurons control three different types of cells, the first being smooth muscle cells present in all structures all over the body that are controlled by different neurons. The two big parts of the autonomic nervous system are the sympathetic nervous system and parasympathetic nervous system. The former starts in the middle of the spinal cord and the latter arises from the spinal cord as a plexus of the interconnected nerve roots arranging to form single nerves.
7. What are the names of the two parts of the autonomic nervous system? What are their functions?
The two divisions of the autonomic nervous system are the Sympathetic nervous system and Parasympathetic nervous system. The former prepares the body for fight and flight response whereas the latter restores the body for calmness and relaxation and avoids it from overworking. The Sympathetic nervous system function is to prepare the body to deal with conditions of fear and stress that respond through a network of interconnected neurons.
The Parasympathetic nervous system function is to respond to the body’s relaxation, resting and feeding state. It decreases the heart rate and respiration; and increases the digestion process.
