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Mother Brain and Baby Brain
What's the deal with
S T R E S S?
A plague of butterflyies swarms the stomache before an exam, when a deadline approaches, after a relationship ends. "Why the butterflies?" a nervous boss wondered recently gripping his abdomen. The quest for an answer to this seemingly simple question required a queasy journey into the world of stress and the digestive system. The body really has two brains - the mind's brain,
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Ultimately, the brain in your head rules all the organs. But when it comes to self-knowledge, perhaps the gut - which refers to the entire digestive system, from mouth to anus - may know best.
Of course, not everyone gets butterflies. Some vomit. Some have diarrhea. Some suffer constipation. Why people react in different ways isn't known.
"Who's controlling things? asks University of Ottawa scientist Anthony Krantis in his broad Australian accent. A neuroscientist, Krantis originally wanted to investigate the brain for his PhD thesis years ago. But in the end, he settled on researching nerves of the gut.
The nervous system of the gut now fascinates Krantis. Also known as the enteric nervous system, the little brain is a collection of nerves lining the walls of the digestive system.
Huge, in fact, the little brain contains as many nerve cells as the spinal cord. Many of its chemicals are also found in the actual brain. To study nerves, the gut is so much more accessible than the brain, Krantis says.
Sever the gut from the rest of the body, stick it in a special bath and, remarkably, it still works, sweeping particles along rhythmically. The boss isn't the only one with queries about the digestive system. For researchers, there are still many unanswered questions.
Krantis, part of a University of Ottawa digestive diseases group, is discouraged that the scientific world doesn't pay enough attention to the digestive system. Digestive diseases aren't usually fatal, but they're severely debilitating. He says they aren't considered "sexy", a word medical scientists often use to describe research into heart disease, cancer or AIDS.
Krantis wants to know how the nerves of the digestive tract work normally, and how they become disrupted in digestive diseases. He's studying disorders such as inflammatory bowel disease and Hirschsprung's disease, a congenital nerve problem of the gut.
The digestive system, even with its own brain, is intimately connected to the main brain through paths along nerves. This is where stress comes in.
When being chased by a tiger, for example, digestion isn't a priority. Blood and oxygen are better sent to the heart, the muscles, the lungs. So the brain decides to shut down the gut. It seems to do that by wreaking havoc on normal gut functions.
It's this kind of disruption that produces the digestive symptoms associated with stress, says Krantis, who occasionally get knots in his stomach when stressed and in his spare time wonders why Pepto-Bismol is pink.
Butterflies are small muscle contractions in the digestive tract, directed by nerve signals from the brain, summarizes Mary Perdue, head of an intestinal diseases group at McMaster University in Hamilton.
Perdue, who studies stress and digestive disorders such as the painful irritable bowel syndrome likens the butterfly response to an asthma attack in the lungs. Asthma attacks can also be provoked by stress.
In short, butterflies arise when a higher power doesn't consider the digestive system vital at the moment. Thus disrupted, the gut's normally well-orchestrated muscles contract in an odd way that the mind can perceive. In essence, the gut is robbed of grace.
And that's really the best answer to the butterfly question. The truth is, butterflies aren't well-understood. Nor are the other digestive symptoms of nervousness. "We don't understand vomiting yet. We're still trying to come to grips with it," Krantis says. The subject is important, he adds, because vomiting is a major side effect of chemotherapy.
Under normal circumstances, the body vomits to rid itself of an infectious organism or harmful substance. Such a radical response during emotional stress doesn't seem to make sense. Krantis believes the gut itself triggers vomiting — even though a centre exists in the stem of the brain. Again, which "brain" is in control?
Although the gut seems overly sensitive, Krantis is astonished it can take the abuse it gets, exposed as it is to infectious organisms that come in through the mouth. Think of the gut as an open window to the elements, more outside the body than inside it. That's why the digestive system is also an important immune organ. Interestingly, immune cells in the gut are partly under the control of nerves.
Through her research, Perdue has discovered that the digestive lining becomes leakier under stress, allowing harmful chemicals and even infectious organisms to creep inside the body.
"We should listen to signals from the digestive system," says Perdue. In other words, when the gut senses trouble, try to take it easy. It may know you better than you know yourself!
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