Sympathetic and Parasympathetic Nervous Systems

The sympathetic and parasympathetic are part of the autonomic nervous system in the body. Because they are part of the same system, their functions can be confused by some as being essentially the same. However, there are notable differences between the sympathetic and parasympathetic nervous systems.

To better understand the differences between the two systems, it is important to understand what they are and how they function.


Sympathetic Nervous System

This system originates in the spinal column area along the lumbar and thoracic regions. The “fight or flight” mechanisms are found here and dictate how your body reacts to danger. So, if you feel that you are in danger, the sympathetic nervous system will direct you to flee or fight depending on the circumstances.


Parasympathetic Nervous System

Here, this system also stems from the spinal cord, but along the medulla and it controls the homeostasis or the overall maintenance of the systems of the body itself. So, the “rest & digest” functions are found here as they are part of the homeostasis found in everyone.


Differences Between Systems

In addition to covering different functions of the body, the systems also differ in terms of how they affect the body.

The sympathetic responses in the nervous system tend to create more alertness, tension, and helps to speed things up so that your reactions are heightened. The functions of the body that are not connected to survival are tamped down. The symptoms that coincide with the sympathetic response includes the following;

  • Muscle Contraction
  • Increased Heart Rate
  • Dilation of the Eyes & Bronchial Tubes in Lungs
  • Adrenaline Released into Body
  • Decrease of Saliva Production
  • Shutdown of Digestive Process in Stomach
  • Lower Urine Output

In essence, the non-essential functions of the body become secondary so that all the energy can be used for survival. This heightened state allows for a person to react quicker and with less distractions to survive.

The parasympathetic responses are the opposite of the sympathetic ones. Instead of pumping up the body, it brings about a calmer state. The responses caused by this system include the following;

  • Relaxing of Muscles
  • Lower Heart Rate
  • Constriction of Bronchial Tubes and Pupils in the Eyes
  • Increase in Production of Saliva and Urine
  • Stomach Begins Digestive Processes

Put simply, the sympathetic and parasympathetic nervous systems use a similar means to communicate to the body their effects. However, what they do is decidedly different in terms of affecting the body’s systems. Each system does this through the autonomic nervous system which has a direct effect on the organs of the body itself.

This means that each system is not under direct conscious control in terms of moving muscles. Instead, the effects come into play when the body is preparing to do different things under different circumstances. The threat of bodily harm for example causes the sympathetic nervous system to react while a state of calm brings about the parasympathetic system. Each works to compliment the other depending on the state of being in the body.