Health

Differences between sympathetic and parasympathetic nervous system

The nervous system is the set of organs and structures formed by nervous tissue, whose main function is to receive and process information from the environment and inside the body, in order to regulate the functioning of the other organs and systems of the same.

The nervous system is divided into two parts: the central nervous system and the peripheral nervous system. Within the peripheral nervous system is the autonomic or vegetative nervous system, which regulates involuntary or unconscious functions in the body such as bowel movement. Likewise, the autonomic nervous system in turn is divided into the sympathetic nervous system and the parasympathetic nervous system, the object of study of this article and whose definitions we will see below and then show their differences.

Sympathetic Nervous System

The sympathetic nervous system originates from the spinal vertebrae beginning in the first thoracic segment of the spinal cord, extending upward to the second or third lumbar segment. The main function of the sympathetic nervous system is to mobilize the body’s response under stressful circumstances, that is, it is the system that mediates the hormonal stress response.

The sympathetic nervous system initiates the body’s fight or flight responses to circumstances of hormonal stress. Among the characteristics of the sympathetic nervous system, it can be mentioned that the preganglionic fibers are short, leave the spinal cord and travel within the nerves. Ganglion cells are located in the paravertebral sympathetic trunks or prevertebral ganglia and their postganglionic neuron releases epinephrine or norepinephrine.

Additionally, the sympathetic nervous system prepares the body for intense physical activity in emergencies. Some of the minor functions of the sympathetic system are dilating the pupils, increasing the force and frequency of the heartbeat, dilating the trachea and bronchi, stimulating the adrenal glands, and contracting the sphincters.

Parasympathetic Nervous System

The parasympathetic nervous system is responsible for the internal organ regulation of digestion, rest and activities that occur when the body is at rest such as sleep. Being a resting system, it gives priority to the activation of the peristaltic and secretory functions of the digestive and urinary systems, at the same time that it promotes the relaxation of the sphincters for the evacuation of excreta and urine.

Its main function is to control all the involuntary acts and functions of the organism. Similarly, among the characteristics of the parasympathetic nervous system, it can be mentioned that it is born in the brain and the sacral region, the preganglionic fibers are long, they leave the brain and do not travel through the nerves. Ganglion cells are located in small ganglia near the viscera or within the visceral plexuses, and their postganglionic neuron releases acetylcholine.

On the other hand, the basic parasympathetic system consists of the functions and actions that do not require an immediate reaction in the surroundings. Finally, some of the minor functions of the parasympathetic system are: constrict the pupil, decrease the strength and frequency of the heartbeat, relax the sphincter, contract the bronchi, lower blood pressure and increase oxygen circulation to non-vital organs. if required.

Taking into account the above, the following differences are presented:

Sympathetic Nervous System Parasympathetic Nervous System
The main function of the sympathetic nervous system is to mobilize the body’s response under stressful circumstances. Its main function is to control all the involuntary acts and functions of the organism.
It causes dilation of the pupils. It causes constriction of the pupils.
It increases the heart rate, thus causing an increase in blood pressure. It slows the heart rate, thus causing a drop in blood pressure.
It stimulates the adrenal glands and contracts the sphincters. Increases oxygen circulation to non-vital organs and relaxes the sphincter.

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