500 million neurons and controls important reflexes, such as peristalsis, the contraction of muscles in the gut to enable digestion.
It is also responsible for the secretion of digestive enzymes that help break down food.The ENS is also a critical part of the gut-brain axis, through which the gut communicates with the brain — and the vagus nerve is particularly essential for conveying information about the intestines to the brain.
The gut-brain axis performs several functions. The majority of serotonin, a neurotransmitter associated with mood, is found in the gut, for example.