My name is Brian Gulbransen,
and I'm an Assistant Professor
in the Neuroscience Program
and Department of Physiology
at Michigan State University.
In this lecture, I'll be discussing how neurons and glia
interact with one another using purines
in the enteric nervous system of the gastrointestinal tract.
The gastrointestinal tract is a very complex place,
and proper gut function is essential to life.
The gastrointestinal tract
is our only route of nutrient absorption
and this requirement to nourish the organism
places a special burden on the gut.
In addition to absorbing nutrients,
the gut also has to protect us from pathogens and toxins,
food antigens, environmental irritants,
parasites, and infectious agents.
The gut also has to move food along its length,
digest the food, and absorb the nutrients.
These are pretty complex processes,
so the gut needs a "brain"
to organize, initiate, and detect all these processes.
In fact, the gut does have its own "brain"
called the enteric nervous system.
The enteric nervous system is a continuous ganglionated network extending the length of the gut.
Now remember that ganglia in the periphery
are collections of peripheral neurons,
and this nervous system is extensive,
so it extends the length of the gastrointestinal tract,
and it contains about the same number of neurons
as the spinal cord or the brain of a cat.
The enteric nervous system was originally classified
as a third division of the autonomic nervous system
by Langley in 1921.
It functions to provide local control of gut functions
such as motility, secretion, and absorption.
The ENS contains many neurotransmitters
and messenger systems,
and is able to carry out simple programmed functions
in the absence of central nervous system input,
such as peristalsis.