Autonomic nervous system: structures and functions

This division of the nervous system controls and regulates vital functions of great importance.

Throughout our lives we perform a large number of actions. We run, jump, talk....

All these acts are voluntary elements that we do voluntarily. However, we also However, we also do a lot of things that we are not even aware of, many of which in fact are what keep us alive and able to do the voluntary ones, such as controlling heart and respiratory rate, speeding up or slowing down physiological systems, or digestion.

At the neurological level, these two types of actions are carried out by two distinct systems, with conscious actions being carried out by the somatic nervous system and unconscious actions by the autonomic nervous system..

What is the vegetative nervous system?

The autonomic nervous system, also called the vegetative nervous system, is one of the two divisions that have been made of the nervous system at the functional level. This system is responsible for connecting the neurons of the central nervous system with those of the rest of the body systems and organs, forming part of both the central nervous system and the autonomic nervous system.It is part of both the central nervous system and the peripheral nervous system. Its basic function is the control of the internal processes of the organism, that is to say of the viscera, being the processes governed by this system beyond our control.

The connections with the different target organs of this system are both motor and sensitive, having both efference and afference. It is therefore a system that sends information from the parts of the brain to the organs, provoking in them a specific reaction or action, while at the same time it recaptures information about its state and sends it to the brain, where it can be processed and acted upon. In spite of this, in the autonomic nervous system predominates the presence of efferentsthat is to say, its function is mainly to emit signals in the direction of the organs.

The neurons of the autonomic nervous system that connect with the various organs of the body generally do so through the ganglia, there are pre- and postganglionic neurons.. The action of the preganglionic neuron is always due to the action of acetylcholine, but in the neuron that interacts between the ganglion and the target organ the hormone released will vary according to the subsystem (acetylcholine in the parasympathetic nervous system and noradrenaline in the sympathetic nervous system).

Main function

The autonomic nervous system is one of the most vital systems for keeping us alive, mainly due to the function it performs.

The main function of this system is the control, as we have already indicated above, of unconscious and involuntary processes, such as breathing, blood circulation or digestion. It is in charge of keeping the processes of the internal organs and viscera in shape and activated.It is also responsible for the detection and control of internal problems.

It also prepares us to face specific situations mediated by the environment, such as the secretion of saliva or digestive enzymes at the sight of food, the activation in the face of possible threats or the deactivation and regeneration of the system through rest.

Any organism with the complexity of vertebrate animals needs a complete nervous system, with a central nervous system and a peripheral nervous system, to coordinate the different parts of the organism. And among invertebrates we also find simple nervous systems, and other complex ones, such as that of the octopus. This is because among animals it is necessary to adapt to changes in the environment quickly, when moving, unlike fungi and plants.

What controls the autonomic nervous system?

As part of the nervous system in charge of controlling the correct unconscious visceral functioning, the autonomic or vegetative nervous system is found innervating most organs and body systems, with the exception of the muscles and joints that govern voluntary movement.

Specifically, we can find that this system controls the smooth musculature of the viscera and various organs such as the heart and lungs.. It also participates in the synthesis and expulsion of most of the secretions towards the exterior of the body and part of the endocrine ones, as well as in the metabolic processes and reflexes.

Some of the organs and systems in which this system is involved are as follows.

1. Vision

The autonomic nervous system governs the opening of the pupil and the ability to focus the gaze, connecting with the muscles of the iris.by connecting with the muscles of the iris and the eye as a whole.

2. Heart and blood vessels

The heartbeat and Blood Pressure are fundamental elements of human beings are fundamental elements for the human being, which are governed unconsciously. Thus, it is the vegetative nervous system that is responsible for regulating these vital elements that keep us alive second by second.

3. Lungs

While we are able to control our breathing to a certain extent, the fact of breathing continuously breathing continuously is not conscious, just as it is generally not consciously controlled by the vegetative nervous system.The rate at which we need to inhale is generally not conscious, nor is the rate at which we need to inhale. Thus, breathing is also partially controlled by the autonomic nervous system.

4. Digestive tract

Through food, the human being is able to acquire the various nutrients needed by the organism to continue functioning. While the behavior of eating is consciously controlled, the process by which the digestive tract transforms the food and acquires from it the necessary components is not, being the set of actions that the organism performs during digestion. involuntary and governed by part of the autonomic nervous system.

5. Genitalia

Although the sexual act itself is performed consciously, the set of physiological elements and reactions that allow its realization are controlled mainly by the autonomic system, which governs processes such as erection and ejaculation. processes such as erection and ejaculation.. In addition, these processes are complicated when a feeling of fear or anxiety is experienced, something that links it to various physiological states.

6. Secretion of enzymes and waste products

Tears, sweat, urine and feces are some of the substances that the organism expels to the environment. Their secretion and expulsion is due to and/or may be altered in part due to the functioning of the autonomic nervous system.. The same occurs with the secretion of digestive enzymes and saliva.

Parts of the autonomic nervous system

Within the autonomic nervous system we can find a series of subdivisions of great importance, which carry out differentiated functions. Specifically the sympathetic and parasympathetic nervous systems stand out.which perform opposite functions in order to allow the existence of a balance in the activity of the organism.

A third system can also be found, the enteric systemwhich is mainly responsible for the control of the digestive tract.

Pexels

1. Sympathetic nervous system

Being one of the divisions of the autonomic nervous system, the sympathetic system is responsible for preparing the organism for action. is responsible for preparing the organism for action, facilitating the fight or flight response.facilitating the fight or flight response to threatening stimuli. To this end, it produces an acceleration of some of the body's systems and inhibits the functioning of others, expending a great deal of energy in the process.

The mission of this part of the autonomic nervous system is to prepare the organism to respond in an agile manner to risk situations, deprioritizing certain biological processes and giving priority to those that allow us to react with agility. That is why its function is of ancestral characteristics, although it is no less useful for that reason; it adapts to modern life situations and can be activated by relatively abstract ideas, such as the certainty that we will be late for a company meeting.

2. Parasympathetic nervous system

This branch of the autonomic nervous system is the one that is responsible for returning to a state of rest after a period of high energy expenditure.. It is in charge of regulating and decelerating the organism, allowing the recovery of energy while allowing the functioning of various systems. In other words, it is responsible for the regeneration of the organism, although it also intervenes in the generation of orgasm, something that does not seem to have much to do with the other functions with which it shares biological roots.

3. Enteric nervous system

The parasympathetic nervous system also has a clear influence on the digestive tract. a clear influence on the digestive tract, there is a subdivision of the enteric nervous systemThere is a subdivision of the autonomic nervous system that specializes almost exclusively in the system by which we incorporate nutrients into our organism. This is the enteric system, which innervates the digestive tract and regulates its normal functioning.

As it is in charge of one of the most important systems for survival, the enteric nervous system has to be fundamentally automatic, and constantly concerned with maintaining the biochemical balance that exists in the different environments of the organism, adapting itself to the alterations that may occur depending on what is ingested, the state of activation, the hormones circulating in the blood, etc.

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