parasympathetic nervous system function

Parasympathetic nervous system functions & structure

The parasympathetic nervous system function (PSNS) is one of the two divisions of the autonomic nervous system (the division of the peripheral nervous system (PNS)), the other is the sympathetic nervous system. The autonomic nervous system is responsible for regulating the unconscious actions of the body. The parasympathetic nervous system function is responsible for stimulating “rest and digestion. The feeding and reproduction” activities that occur when the body is resting, especially after eating, including sexual arousal, drooling, tearing (tears), urination, digestion, and defecation. 


The nerve fibers of the parasympathetic nervous system arise from the central nervous system. Specific nerves include several cranial nerves, in particular, the oculomotor nerve, the facial nerve, the laryngopharyngeal nerve, and the vagus nerve. Three spinal nerves in the sacrum (S2-4), commonly referred to as pelvic span nerves, also act as parasympathetic nerves.


The parasympathetic nervous system function


Intravital nerve supply fibers that transmit sensory information from the internal organs of the body back to the central nervous system are not divided into parasympathetic and sympathetic fibers as drainage fibers: 34-35 Instead, autonomic sensory information is carried out by visceral afferents generally.


General visceral sensations are mostly unconscious visceral motor reflexes from the hollow organs and glands that are transmitted to the CNS. While unconscious reflex arcs are usually undetectable, in some cases they can send pain sensations to the CNS masked, like the mentioned pain. If the peritoneal cavity becomes inflamed or if the gut suddenly expands, the body will interpret the effective stimulus of pain as being somatic at first. This pain is usually not located. 


Vascular effects

Heart rate is largely controlled by the action of an internal pacemaker. Cardiac cells exhibit automatism, which is the ability to generate electrical activity independent of external stimulation. 

In parasympathetic nervous system function, the absence of any external stimuli, peripheral stimulation contributes to maintaining heart rate in the range of 60-100 beats per minute (bpm). At the same time, the two branches of the autonomic nervous system activity in a complementary way. It increases or slowing down the heart rate. In this context, the vagus nerve acts on the sinoatrial node, slowing its conduction, actively modulating the vagus nerve tension, respectively. 

The vagus nerve plays a key role in regulating the heart rate by modulating the sinus node response, the vagus nerve tone can be quantified by examining the modulation of the heart rate caused by changes in the vagus tone.  The main mechanism of the parasympathetic nervous system for vascular and cardiac control is the so-called nasal sinus arrhythmia (RSA). 

Sexual activity

Another role played by the parasympathetic nervous system is sexual activity. In males, cavernous nerves from the prostate plexus stimulate smooth muscles in fibrous tufts of rolled penile arteries to loosen. It allows the blood to fill the two corpus cavernosum and the penile spongy body. It made them stiff to prepare for sex. action. After separating the ejaculate, sympathetic people interact with each other and cause peristalsis of the auditory canal and closure of the internal urethral sphincter to prevent sperm from entering the bladder. At the same time, Paralympics cause peristalsis of the urethral muscle.


In parasympathetic nervous system function, the pudendal nerves cause a contraction of the tuberculous to secrete the strength of the semen. During remission, the penis becomes flabby again. In females, there is erection tissue analogous to male, but less important, which plays a large role in sexual stimulation. PN causes secretion in the female, which reduces friction. Also in women, the parasympathetic innervate the fallopian tubes, which helps peristaltic cramps and the movement of the oocyte to the uterus for implantation. Secrets from the female genital system help in the migration of sperm. PN (and SN to a lesser extent) play an important role in reproduction.


Other parasympathetic nervous system function (receptors)

The parasympathetic nervous system mainly uses acetylcholine (ACh) as a neurotransmitter, although peptides (such as cholecystokinin) may be used. ACh acts on two types of receptors, muscarinic and nicotinic cholinergic receptors. Most of the transmission proceeds in two stages: after stimulation. The neurotransmitter releases ACh in a ganglion that acts on the nicotinic receptors of postganglionic neurons. Postganglionic neuron then releases ACh to stimulate muscarinic receptors on the target organ.



The parasympathetic nerves are autonomic or sensory branches of the peripheral nervous system (PNS). Restoration of the parasympathetic nerve arises in three main areas:


Certain cranial nerves in the skull, namely the parasympathetic nerves usually arise from specific nuclei in the central nervous system. (CNS) and synapse in one of the four parasympathetic ganglia: cilia, pterygopalatine, or submandibular. Of these four ganglia, the parasympathetic nerves end their journey to target tissues through the trigeminal branches (optic nerve, maxillary nerve, mandibular nerve).

The vagus nerve does not participate in these cranial ganglia, because most parasympathetic fibers are intended for a wide range of ganglia on or near the torso (esophagus, trachea, heart, lungs) and abdominal viscera (stomach, pancreas, liver, kidney, small intestine, and about half large intestine). The vicious labyrinth ends at the intersection between the medial and posterior mediastinum. It just before the bending of the lateral spleen of the colon.


Cerebral nerve

Cerebral nerve cells from the pelvic area are found in the side-gray corner of the spinal cord at the level of T12-L1 vertebrae (spinal cord ends on L1-L2 vertebrae with a spinal cone) and their axons emerge from the spine as S2-S4 spinal nerves by the pouch. Their axons continue from the CNS to the synapse on the autonomous coil. 


This differs from the sympathetic nervous system, where synapse of the nerve nerves before and after the ganglia is present in the ganglia located further away from the target organ.

Like in the sympathetic nervous system, signals of the parasympathetic nerve are transferred from the central nervous system to their targets by means of a system of two neurons. Its cellular body is located in the central nervous system. Its axon usually extends to the synapse with postganglionic dendrite elsewhere in the body.  As a result, post-synaptic parasympathetic nerve fibers are very short.

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