The autonomic nervous system is a part of the peripheral nervous system and regulates certain body processes, such as the rate of breathing and blood pressure and influences the function of the internal organs. This function is automatic, and works without a person’s aware consciousness. It also works in correlation with the somatic nervous system.


What is the autonomic nervous system?

The autonomic nervous system is the part of the peripheral nervous system that controls the functions of internal organs and supplies these organs, and incorporates the liver, stomach, bladder, genitals, lungs, heart, blood vessels, stomach, sweat and salivary glands as well as the digestive glands and some muscles.

It can be divided into three parts: the sympathetic nervous system (readies the body for stressful situations), the parasympathetic nervous system (regulates the body process during normal situations) and the enteric nervous system. The sympathetic nervous system originates from the spinal cord , especially at the level of the thoracic and lumbar regions. The extensions of the neurons present here make for a number of structures, the ganglia, located near the spinal cord. For this reason we speak of preganglionic fibres (those that originate in the bone) and postganglionic fibres (those that start from ganglion). These make for a muscle or gland. Only few preganglionic directly contact other ganglia other than these mentioned above.

The bodies of the neurons of the parasympathetic system are found in the sacral region of the spinal cord and the medulla oblongata of the brain stem, where the cranial nerves III, VII, IX and X form the preganglionic parasympathetic fibres. These and those originating from the spinal cord make for ganglia, which is very close to the department and thus must be controlled. From here postganglionic fibres are routed directly to the target organ.

The enteric nervous system is instead formed by a set of nerve fibres that innervate the viscera.


What function does the autonomic nervous system serve?

The autonomic nervous system controls body functions at rest and reflex reactions (fight or flight) to ensure smooth acts on the muscles (such as those in the skin around the hair follicles, those around blood vessels, those in the eye and those of the stomach, bowel and bladder) and of the heart.

In general, the sympathetic and the parasympathetic divisions primarily control numerous organs within the body, even though these exert opposite effects on certain targets. In this way control functions such as the dilation of the pupils, the production of saliva and mucus, heart rate, contraction of the muscles of the bronchi, the movements of the stomach and intestine, the accumulation of glycogen in the liver , urine production , the relaxation of the bladder wall and the opening of its sphincter. An example of this is that the parasympathetic divisions’ function is to decreases the blood pressure in the body, while on the other hand the sympathetic division increases the blood pressure in the body. However these divisions work together to regulate and guarantee that the body responds to different situations and needs accordingly.