Both our body and our mind are regulated by the brain and all the connections it contains. The nervous system is responsible for conducting signals between neurons and thus coordinating all the actions of the body. The human nervous system can be divided into two large parts: the central nervous system (or CNS), made up of the brain and the organs closest to it, and the peripheral nervous system (or PNS), made up of the nerves and neurons that They are located outside the central nervous system.
In this Psychology-Online article, we will focus on a very specific part of the PNS: the autonomic nervous system (ANS). In addition, we will explain the main functions and differences between the sympathetic and parasympathetic nervous system: two major ramifications of the ANS, very important in our own survival as human beings.
The autonomic nervous system: definition
As we have mentioned previously, the ANS (also known as the vegetative nervous system) is located in the periphery of the nervous system, despite being activated by areas such as the hypothalamus, most of its activity is focused on the spinal cord, the nerves peripherals and the brain stem. The nerves that leave the brain and go directly to all the organs of our body (efferent fibers) are part of the autonomic nervous system.
This anatomical organization is due to the fact that it receives and sends information from the viscera and many of the organs of our body in order to correctly regulate and stimulate its vegetative functions.
Functions of the Autonomous Nervous System
It has been shown that this system controls the muscles that surround our organs, regulates the excretory system (sweat, urine and other secretions) and participates in the following processes:
- Control of reflexes and involuntary actions
- Blood pressure
- Breathing
- Digestion
- Erection and ejaculation
- Involuntary muscle contraction and relaxation
- …
So that we understand it better, and as a summary, everything that our body does and that we do not usually pay attention to, is controlled by the autonomic nervous system.
Parts of the Autonomous Nervous System
This organization of nerves and neurons is divided into three main parts:
- Sympathetic Nervous System: responsible for regulating the body’s activation responses
- Parasympathetic Nervous System: responsible for returning to the state of balance and conservation after activation of the sympathetic system.
- Enteric Nervous System: Also known as the “second brain”, this system is the least known of the three, it is responsible for generating emotional responses from the secretion of neurotransmitters such as dopamine and endogenous opioids. Thanks to this system, we understand better.
Next, we will develop in depth the concepts of Sympathetic and parasympathetic nervous system: their main differences and functions.
Difference between the sympathetic and parasympathetic nervous system
Now that we know that we have a built-in system responsible only for controlling the involuntary functions of our body, it is normal to want to know more, What does each system do? While it is true that each of those mentioned above has a specific function, it is important to know the close relationship that exists between the sympathetic and parasympathetic nervous systems.
Both are different sides of the same coin, they are responsible for keeping our body in balance or homeostasis to different external stimuli. However, the main difference lies in its functions: while one is responsible for activating our body, the other is responsible for relaxing it and returning to the body’s natural state.
Function of the Sympathetic Nervous System
The nerves, fibers and neurons of this system are responsible for putting our body in a state of physiological alert. When the brain sends an alert signal or cortical activation due to a stressful situation, the SNS sends a message to the muscles and glands of our body to get our body moving in the following way:
- The adrenal gland releases adrenaline throughout our bloodstream
- Dilates the pupils
- Accelerates heart rate
- Opens the airways to increase oxygen in the blood
- Inhibits the digestive system to concentrate efforts on attack and flight tasks
- Maintains muscle tone
- Stimulates orgasm
Parasympathetic Nervous System: functions
In contrast to the SNS, we find the SNP. This system is responsible for returning all previously activated organs to our natural state. To do this, it sends signals to the brain so that it releases acetylcholine and reaches the neurons responsible for relaxing the muscles and organs. The parasympathetic nervous system has the following main functions:
- Pupil constriction
- Reduction in lung volume
- Decreased heart rate
- Stimulation of the digestive process
- Muscle relaxation
- Stimulation of sexual arousal (in this case, it is not the opposite response to the SNS, but rather it complements it)
Diseases of the sympathetic and parasympathetic nervous system
As we have seen, this set of neurons and nerves is extremely important for our survival. Presenting a disease in either system can be a serious problem and we must detect it as soon as possible.
An imbalance in the SNS or PNS will be related to our ability to generate appropriate body responses to our environment. The main examples of diseases of the sympathetic and parasympathetic nervous system are the following:
- : When the parasympathetic nervous system does not function properly, this disease can appear, characterized by enormous pain with no apparent physical explanation.
- Multiple sclerosis: This neurodegenerative disease can appear due to the interaction of different factors, one of them is a failure in the autonomic nervous system.
- Parkinson’s: Although the appearance is not directly related to a failure in the ANS, the fact of presenting this disease can lead to serious dysfunction in said system.
- Hypotension Idiopathic orthostatic: also known as pure autonomic failure
- Diabetes: This endocrine imbalance is closely related to a malfunction of the parasympathetic nervous system. As we have seen previously, the parasympathetic nervous system is responsible for also regulating some of the functions of the digestive system.
- Other diseases such as botulism, leprosy and chagas disease They can cause failures in the nervous system.
Summary of the anatomy and functions of the Autonomous Nervous System
By presenting so many names and technicalities, we have found it necessary to create a simple summary in order to correctly understand both the ANS and the sympathetic and parasympathetic nervous system:
1. Anatomy
The ANS is part of our peripheral nervous system, it is responsible for generating responses in our brain and controlling most of our organic functions. We understand, then, that the ANS is distributed throughout the body and is anatomically differentiated from the Central Nervous System due to its position on our body map.
The nerves, brain stem, spinal cord and some parts of the hypothalamus are the areas most involved in the autonomic nervous system. In turn, we divide the ANS into: sympathetic, parasympathetic and enteric nervous systems (SNS, PNS and ENS)
2. Functions
The main function of the ANS is to control our unconscious and vegetative functions. For example, we are not aware of the digestive process, however, there is a part of our system responsible for regulating it. The same thing happens with involuntary muscle tension, breathing and many more adaptive responses.
3. Differences between SNS and SNP
The sympathetic and parasympathetic nervous systems are responsible for keeping our body in constant balance, while the SNS is responsible for activating alert functions when a stimulus causes us stress, agitation or we perceive danger, the PNS is what directs our body. to a state of tranquility and conservation.
This article is merely informative, at Psychology-Online we do not have the power to make a diagnosis or recommend a treatment. We invite you to go to a psychologist to treat your particular case.
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