Friday, August 12, 2011

The Human Nervous System: Is it a Bear or a Tree Stump?

The feeling of dread in your stomach.  The sweaty hands.  What does it mean and why does it happen?

The human body has two systems that regulate a whole lot of important things.  They are the sympathetic nervous system and the parasympathetic nervous system.

The sympathetic nervous system is in charge of preparing your body for stress and maximum efficiency.  Say for example, you walk in a forest and suddenly a bear jumps out in front of you.  Your pupils dilate and your heart rate increases, along with your blood pressure.  Also, your lungs expand and blood is diverted from your skin and digestive organs to the brain and skeletal muscles.  All this is in order to prepare you for either the fight or flight reaction.

The parasympathetic nervous system calms you down again.  When the bear in the forest turns out to be a tree stump, you relax and your parasympathetic nervous system kicks in.  Your pupils limit the amount of light coming in and your heart rate and blood pressure returns to normal.  Your muscles relax and the blood flow is returned to its previous setup.

These two systems basically work together to ensure that your body is regulated optimally so that you are ready for whatever you are facing, whether it be a bear or a tree stump.

To ensure that you remain safe, the sympathetic nervous system kicks in even before you’re sure of what you’re facing, just in case.  You see a dark shape looming in front of you and your mind automatically calls down a memory of what a bear might look like and your sympathetic nervous system reacts accordingly, so that you might be ready.

The downside in all this is that the body often overreacts, specifically in this age, where the most danger one faces is cutting one’s hand on paper.  Even though we live in relatively safe environments (in contrast to our ancestors) our bodies still react as though we’re in constant danger.

Because of this, every new thing we face, be it a tree stump or a publishing deal, will send our bodies into overdrive, preparing to fight for survival.  This pushes many people to stay in their safe environments, never trying anything new.  They trust their bodies to tell them what is dangerous, while the sympathetic nervous system is still living in the Stone Age, unable to see when we’re not in danger.

While your body can prepare you for danger, it can also lead you into a life of no growth.  Think before you listen to your sympathetic nervous system.  Don’t just run.


  1. Good point. Some things aren't as dangerous as your body might tell you at first . . . or at least not in the same way.

  2. I suppose that some things might seem innocent, while your body might know something you don't (You might "damage" yourself by taking on anxiety from a big assignment).