Parasympathetic nervous system: characteristics and functions

Relax after an effort or a stressful situation. Regulate heartbeat after a run or a shock. Relax our lungs and reduce the entry of oxygen and thus promote a state of calm. All of these processes, so essential in our daily lives, are regulated and controlled by an essential part of our body: the parasympathetic nervous system.

Beyond what it may seem, the topic is undoubtedly interesting in many more aspects than we think. It is because knowing how this type of structure works makes it easier for us to better understand why we are the way we are, and in turn, discover how we can mediate our health and well-being.

An example of this is what is explained to us in studies such as the one carried out at Harvard Medical University and published in the journal Music Perception. According to this work, music has a therapeutic effect on the parasympathetic nervous system in people who have alterations in this area. It does this by improving its activity and functions. This is undoubtedly explained by its ability to promote calm and relaxation, thus mediating that characteristic that defines said system. Let’s see more data below.

SNP characteristics

The parasympathetic nervous system is a division of the autonomic nervous system which facilitates the restoration of body energy. To do this, it controls the activity of smooth and cardiac muscles. Its action occurs independently of the will of the subject.

Therefore, this system has efferent pathways to various target organs, such as the eyes, different glands, heart, lungs, intestine, etc. Let’s see its distribution in detail.

Where is the parasympathetic nervous system distributed?

As we have already pointed out at the beginning, the parasympathetic nervous system is part of the autonomic nervous system. Let’s see, however, in detail how it is distributed:

Cranial area: In this area the parasympathetic nervous system connects with the hypothalamus, the midbrain and the hindbrain. Likewise, the vagus nerve is of great relevance here, which reaches the heart, lungs and digestive tract to carry out vital functions. The oculomotor nerve (pair III), the facial nerve (pair VII) and the glossopharyngeal nerve (pair IX) are also outputs from the cranial area.Sacral area: This region is no longer connected intracranially, but in the spinal cord itself. Here it innervates from S2 to S4 with the urogenital area to regulate tasks such as urination.

In addition, It should be noted that communication between neurons is carried out through acetylcholine, both at the preganglionic and postganglionic levels. The receptors responsible for collecting this neurotransmitter are called nicotinic and muscarinic.

Functions of the parasympathetic nervous system

We know that the sympathetic nervous system mediates our energy savings. That is, it helps us go from a state of alert to one of calm. However, it must be said that it carries out more tasks, more functions essential for our survival and that we perform unconsciously or involuntarily. You can read them below.

Cardiovascular system

The functions of the parasympathetic system in the cardiovascular system are controlled by the vagus nerve. Thus, its main task is to regulate the heart rate, both the frequency and the strength of the contraction. It also reduces blood pressure.

Likewise, and no less interesting, it should be said that thanks to the parasympathetic system we can improve cognitive processes as important as memory, attention, problem solving, etc. According to a study published at the Ruhr University of Psychology Bochum, in Germany, when our heart rate is regulated and the heart rate is less accelerated, our brain works much better.

Digestive system

Mediates the digestion process in various ways: controls the stomach wall by facilitating contractions and peristaltic activity and facilitates the secretion of hormones such as gastrin, secretin and insulin. It also regulates salivation and swallowing.

On the other hand, there is an aspect that we cannot forget: digestion demands a high energy cost. Thus, What the parasympathetic nervous system does is focus all the energy during this process on our digestive system.

Excretory system

The parasympathetic system intervenes in the evacuation process. Controls and regulates urination and defecation through the contraction of the sphincters.

genital system

This structure made up of nerves and ganglia has a key relevance in our sexuality. Thanks to this system, sexual arousal is favored.

Respiratory system

The function of this system in our lungs is key to stimulating bronchoconstriction. That is, that mechanism by which the airways narrow to block or reduce the flow of oxygen we receive.

visual system

Parasympathetic fibers also stimulate contraction of the ciliary muscle which leads to relaxation of the lens, allowing us to focus our eyes on close objects. On the other hand, it also favors the contraction of the pupil when one comes out of a state of alert.

To conclude, as we have been able to discover, the human body is as complex as it is perfect at the same time. We are those beings prepared to react to any stimulus, to adapt to any circumstance and regulate our body according to our needs. Understanding each process of the autonomic nervous system (including the sympathetic and parasympathetic systems) undoubtedly allows us to know much more about ourselves.

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