脑肠轴brain-gut axis

3. Describe the "Brain-Gut Axis" and explain how it relates to material covered in class. You may use the following article as a starting point.

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Gut Feelings: The Surprising Link Between Mood and Digestion

Chris Woolston

CONSUMER HEALTH INTERACTIVE

Below:

•Listening to your gut

•The stress alarm

•Functional disease in a dysfunctional world

•Setting your mind on relief

If you've ever felt your insides twist in knots before a big speech, you know the stomach listens carefully to the brain. In fact, the entire digestive system is closely tuned to a person's emotions and state of mind, says William E. Whitehead, PhD, a professor of medicine and an adjunct professor of psychology at the University of North Carolina. People with irritable bowel syndrome often suffer flare-ups during times of stress and anxiety, and even perfectly healthy people can worry their way to stomach pain, nausea, diarrhea, constipation, or other problems. Even if a doctor can't find anything physically wrong, the misery is real.

In the past -- back when scientists believed the mind and the body operated as separate entities -- some physicians wrote off digestive distress with no sign of organic disease as being "all in the head." But in recent years, that wall has crumbled. Doctors now see intricate links between the nervous system and the digestive system. The two realms constantly exchange streams of chemical and electrical messages, and anything that affects one is likely to affect the other. The connections between the two systems are so tight that scientists often refer to them as one entity: the brain-gut axis. (The brain-gut axis is a hot topic in medicine. In the summer of 2001, more than 100 researchers from around the world gathered in Los Angeles for a convention called "2001: A Brain-Gut Odyssey.") For people suffering from persistent digestive troubles unconnected to disease, such research suggests that reducing stress, depression, and anxiety may go a long way toward calming the gut.

Listening to your gut

It may surprise many people to learn that the gut actually contains as many neurons (nerve cells) as the spinal cord. In an article in the medical journal Gut, author J. D. Woods and colleagues compare this network -- known as the enteric nervous system, or ENS -- to a "local mini-brain" storing a library of programs for different patterns of gut behavior." Woods and colleagues compare the ENS to a microcomputer with its own independent software, "whereas the brain is like a larger mainframe with extended memory and processing circuits that receive information from and issue commands to the enteric computer."

With all these messages, the connection between the brain and the digestive system is a busy two-way street. The central nervous system releases chemicals (acetylcholine and adrenaline) that tell the stomach when to produce acid, when to churn, and when to rest. Similar signals help guide the movements of the intestines. The digestive system responds by sending electrical