Does Your Body Have A Second Brain?
The next time you get a gut feeling -- pay attention. It could be
your second brain talking.
"The gastrointestinal tract has an enormous amount of nerves
and neurons," said Dr. Mitchell Cappell, M.D., Ph.D., chief
of gastroenterology and fellowship director at William Beaumont
Hospital, Royal Oak. "It has considerably more neurons than
the entire spinal cord, so it is doing things all the time including
talking or communicating with the brain."
This network is called the enteric nervous system, but is affectionately
known by gastrointestinal docs, who have come to appreciate the
complexity of it, as the "second brain."
"(The second brain) contains reflex circuits that detect
the physiological condition of the gastrointestinal tract, integrate
information about the state of the gastrointestinal tract, and
provide outputs to control gut movement, fluid exchange between
the gut and its lumen and local blood flow," according to
Scholarpedia. "It is the only part of the peripheral nervous
system that contains extensive neural circuits (an estimated 100
million neurons) that are capable of local, autonomous function.
The ENS has extensive two-way connections with the central nervous
system, and works in concert with the CNS to control the digestive
system in the context of local and whole body physiological demands."
Its degree of independence has earned it the second brain title.
Yet, despite this distinction, Cappell said, most of the time
the big brain ignores the gut or does not consciously pay attention
to it, leaving it to do what it does so well: digesting things
such as the double burger, large-size fries and Coke the big brain
thought it had to have. However, there are times when the big
brain experiences physical and emotional sensations that trigger
responses such as the release of stomach fluids, including acid,
bile and bicarbonates, or the sudden spasm of muscles in the gut,
which, in effect, produces the feeling of butterflies in the stomach.
Gut feelings can be elicited by something as unsubstantiated
as the feeling that nobody likes you or something as real as a
dog threatening to bite you.
According to an article by the New York Times, "A study
in 1902 showed changes in the movement of food through the gastrointestinal
tract in cats confronted by growling dogs."
Knowing more about the connection between the two brains is now
helping researchers in the relatively new field of neurogastroenterology
find better ways to treat ailments such as anxiety, depression,
irritable bowel syndrome, ulcers and Parkinson's disease.
January 14, 2010