It's the Rodney Dangerfield of the body. Mocked by many as the "bay window," "spare tire," "big gut," "German goiter," or "beer belly." No anatomical part gets less respect than the stomach.
Medievalists, however, considered it an integral part of the mind-body connection, believing organs, such as the stomach, and their secretions housed the most basic emotions and a variety of human attributes — among them, spirit, courage, valor, pride, resentment, and anger.
It continues metaphorically today. Being fed up makes you angry; not being able to stomach certain people shows your resentment towards them.
For a kinder gentler approach, you'll have to look to your bowels. Originally encompassing all the major organs in the lower half of the body, they are the source of numerous biblical and literary references, including the bowels of compassion, mercy, kindness, and meekness — emotional responses involving your capacity for sympathy and understanding.
Apart from an occasional blockage or unexpected flow, most people don't think much of their gastro-intestinal tract. They take pride however in their intestinal fortitude. It's also there that they find their intuitive sense in their gut reaction. On the down side, it also makes for the "butterflies in your stomach" the nervousness you experience prior to your making a public presentation and the bad case of cramps before a job interview.
For courage in such situations, what you need is some intestinal fortitude. Farmers once thrust their hand down into a slaughtered fowl to "pluck" out their viscera. This gave pluck special status, the word entering 18th century prize fighting slang, underscoring its ties to the guts from the Anglo Saxon guittas, a channel, as the path of courage. Being intrepid in times of danger requires that you also dig down deep inside. It's easy to see why you need guts in such situations.
Your gut reaction bears being listened to. It's often more trustworthy a guide than is a scattered mind. It's something borne out by those "in-the-know". Medical science reveals the entire intestinal system to be as complex as the better studied spinal cord. Like the spinal cord, it also transmits and processes messages. Dr. Michael Gershon, a professor of anatomy and cell biology at Columbia Presbyterian Medical Center in New York, calls it a "second brain". Nearly everything that helps run and control the brain can also be found in the gut — sensory and motor neurons, information processing circuits, as well as the major neurotransmitters: dopamine, serotonin, acetylcholine, nitric oxide and norepinephrine. It even has benzodiazepines, chemicals of the family of psychoactive drugs that includes Valium and Xanax.
Can't stomach this entire disquisition? Then vent your spleen. It may only be a flat, ductless vascular organ lying near the stomach. But it was once regarded as the seat of emotions, such as melancholy, ill temper, and spitefulness. Venting it allows you to release those horrible emotions all at once. Go for it!