How The Human Nervous System Works

How The Human Nervous System Works ?

One of the most vital and complicated systems operating in the human body is the nervous system. This is essentially because of the complex environment of the brain with almost 10 billion neurons housed within and many more billion connectors between them. The human nervous system is truly marvelous and getting an insight into how it works will help you appreciate your nervous system.


The brain is one of the parts of the nervous system which gets its complexity by the inclusion of the central nervous system (CNS) and the peripheral nervous system (PNS). The network of nerves and neurons in the spine and the brain constitute the CNS while those in the rest of the body constitute the PNS.

In some animals with a simple nervous system, the network of sensors is connected directly to the system of skeletons-muscles. Any internal or external input will result in a response called behavior, which is organism-centric. In animals with complex behavior, the nervous system operates independently. The inputs from the surroundings are received by the receptor cells which transfer them to the brain in the form of electric signals. The brain processes the inputs and sends the intended response in signal form to the surrounding environment through different body parts. All these transfers of signals are through he network or nervous system. Most of these responses to the inputs are executed automatically and unconsciously by programs which are hard-wired in the nervous system through centuries of evolution.

The functioning of CNS is most difficult to comprehend or reverse-engineer. Simply stated, study of the CNS will be limited to the spine, brain and the brain stem.

The PNS is broadly divided in to somatic nervous system and autonomic nervous system. These refer to the network of nerves just below the surface of the skin and those all over the body respectively. Although both these systems work on their own, the autonomic system gets its name since it enables maintenance functions of the body which are mostly out of reach of the conscious control. Those nerves which are a part of the conscious control activities of our body are grouped under somatic system. In the state of coma, they tend to function automatically like the autonomic nervous system.

The autonomic system is further divided in to sympathetic, parasympathetic and enteric nervous systems. Response to danger, stress and stimulating adrenalin release is controlled by sympathetic system. Assisting in going to sleep, resting and digesting food is controlled by parasympathetic system. These systems work in tandem in the body. The enteric system can function independent of the other 2 systems and comprises of nerves surrounding the intestines.

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