Once home, I googled autism awareness, bumper sticker, and entered a whole world of autism products. Bumper stickers, of course. But also tee shirts, jewelry, stickers (I am someone with autism), mugs. Eventually, I exited even more perplexed than I entered.
In general, the digestive system is controlled by both nerves and hormones. The nerves that control digestion are in the submucosa layer of the tissue and in between the muscle layers of the walls of the organ.
The duodenum produces many hormones that help regulate digestion. Liver bile and pancreatic secretions are added to the bowel through the ampulla of Vater. The actual passage and presence of food in the duodenum starts the flow of hormones, bile and pancreatic secretions. By the time food leaves the duodenum most of the ingredients necessary for digestion have been added.