The sympathetic and the
parasympathetic nervous system are parts of what is commonly called the
autonomic nervous system. (Autonomic = can not be controlled by the mind).
You can say that these systems work in balance with each other and directly
or indirectly affect almost every structure in the body (e.g. heartfrequence,
heartcapacity, lumbar function, kidneys, blood vessels, stomach and intestines)
The sympathetic
nervous system has an active "pushing" function, the parasympathetic
has mainly a relaxing function.
The sympathetic
nervous system is located to the sympathetic chain, which connects
to skin, blood vessels and organs in the body cavity. The sympathetic
chain is located on both sides of the spine and consists of ganglias.
The autonomic nervous system
is most important in two situations: emergency situations that cause stress and
require us to "fight" or take "flight", and nonemergency situations that allow us
to "rest" and "digest". The autonomic nervous system also acts in "normal" situations
to maintain normal internal functions and works with the somatic nervous system. When
the body reacts to signals about e.g. danger it is the sympathetic ganglia that makes
The lungs and the bronchial tubes are widend to give us more oxygen.
The motility in the intestine is reduced - we shall not digest food - we must fight or run away!
Blood is sent to the brain while skin and internal organs get less.
Muscel tension is increased.
Heart rate and force is increased.
Below you can find a summary of some
of these effects:
| Sympathetic |
Structure |
Parasympathetic |
| Rate increased |
Heart |
Rate decreased |
| Force increased |
Heart |
Force decreased |
| Broncial muscle relaxed |
Lungs |
Broncial muscle contracted |
| Pupil dilation |
Eye |
Pupil constriction |
| Motility reduced |
Intestine |
Digestion increased |
| Sphincter closed |
Bladder |
Sphincter relaxed |
| Decreased urin secretion |
Kidneys |
Increased urin secretion |
(When you read about the
functions the sympathetic chain has, you wonder how anyone can
allow surgeons to make any operations on such a complicated system....)
Main page /
Background /
Side effects /
Sympathetic nervous system /
News
Why me? /
We want /
Links /
Contact us /
Health tips