Autonomic Vs. Somatic Nervous System

Our brain is a complex organ that manages to control each and every muscle in the body. Every movement, perception and reception of enormous amount of data is all done by the brain. With so many things to do, it is least surprising that all the tasks that are to be performed are delegated to other parts of the nervous system.

The nerves which are spread throughout the body branch out of the brain and spinal cord. This entire system of nerves and ganglia, excluding the central brain and spinal cord, is known as the peripheral nervous system.

The peripheral nervous system is further divided into two main divisions, structurally and functionally, which are known as somatic nervous system and autonomic nervous system.

The autonomic and somatic nervous system which are the two branches of the peripheral nervous system are poles apart in terms of function, sub-division, targeted organs, etc. As you make your way through the table which provides the details of the two divisions of the peripheral nervous system, you will get well-versed with all the differences between the two.

Autonomic Nervous System:
Its main function is to carry out the functions that are mostly below the normal consciousness level; the visceral functions is an apt example of the same. In short, this is the system that adjusts and maintains the internal environment of the body.

Somatic Nervous System:
It is the part of the peripheral nervous system that is associated with voluntary movements of the body that are within our control, that is, with the help of skeletal muscles. This is basically the system that helps the body to adjust to the external environment.

Autonomic Nervous System:

There are two different neurons that form the pathway of the autonomic nervous system, from the spinal cord to the target organ or tissue. The first neuron, which is the preganglionic neuron, runs from the brain or spinal cord and ends at the postganglionic neuron.

The second neuron, on the other hand, runs from the autonomic ganglion to the effector or the target tissue.

Somatic Nervous System:
The somatic nervous system has a single neuron running from the spinal cord, and directly ending in and innervating the skeletal muscle.

Autonomic Nervous System:
It is further divided into two more divisions - the sympathetic nervous system and the parasympathetic nervous system. At times, the enteric nervous system is also said to be a part of the autonomic nervous system.

Somatic Nervous System:
There are no further subdivisions of the somatic nervous system.

Autonomic Nervous System:
As the autonomic nervous system is further divided into so many different parts, it is but obvious that the target organs for this system are many. Basically, the nerves of the autonomic nervous system are associated with the functioning of internal organs like the heart, lungs, viscera and various glands.

Somatic Nervous System:
The somatic nervous system only innervates the voluntary, i.e. the skeletal muscles.

Autonomic Nervous System:
Stimulation of the autonomic nervous system can lead to various effects. The sympathetic and parasympathetic nervous systems have the exact opposite effect, and help the body adjust instantly to a situation.

The sympathetic nervous system - also referred to as the fight or flight response of the body, increases blood flow to the skeletal muscles and lungs, increases the heart rate, dilates the pupils, inhibits peristalsis and stimulates an orgasm.

The parasympathetic nervous system increases blood flow to the gastrointestinal tract, constricts the pupils, stimulate secretions and peristalsis and also stimulates sexual arousal.

Somatic Nervous System:
The somatic nervous system, since it only innervates skeletal muscles, is solely responsible for bringing about contraction of skeletal muscles, usually in the form of a reflex.

Autonomic Nervous System:
The autonomic nervous system has chain ganglia present along its pathway.

Somatic Nervous System:
There are no ganglia along its pathway.

Autonomic Nervous System:
The neurotransmitters present along the path of the autonomic nervous system include acetylcholine, adrenaline and noradrenaline.

Somatic Nervous System:
The only neurotransmitter that acts along the somatic nervous system is acetylcholine.

As you can see in the table above, differentiating between these two parts of the peripheral nervous system is as good as differentiating between chalk and cheese. Other than the fact that they are both branches of the peripheral nervous system, these two have very little in common.

Thus, it can be safely said that these two parts of the peripheral nervous system work in tandem with each other so as to ensure a state of homeostasis in the body.