The brain interacts with the rest of the body through the nervous system, which has several major components. One of them is the enteric nervous system, which helps regulate digestion. In life-or-death situations, the brain triggers the “fight or flight” response. It slows digestion, or even stops it completely, so the body can focus all of its internal energy to facing the threat. But less severe types of stress, such as an argument, public speaking, or driving in traffic, also can slow or disrupt the digestive process, causing abdominal pain and other gastrointestinal symptoms.