Gut Tissues?
The ENS contains major neurotransmitters like serotonin, dopamine, glutamate, norephinephrine and nitric oxide, as well as two dozen small brain proteins, called neuropeptides along with the major cells of the immune system.
Biological research confirmed that a clump of tissue called the neural crest forms early in embryo genesis. One section turns into the CNS. Another piece migrates to become the ENS.
It is only later that the two systems are connected via a cable called the vagus nerve. (dark blue lines in image)
The brain sends signals to the gut by talking to a small number of “command neurons,” which in turn send signals to gut inter-neurons that carry messages up and down the spine. Both command neurons and inter-neurons are spread throughout two layers of gut tissue called the “myenteric plexus and the submuscosal plexus.”
They also contain glial cells that nourish neurons, mast cells involved in immune responses, and a “blood brain barrier” that keeps harmful substances away from important neurons.
They have sensors for sugar, protein, acidity, and other chemical factors that monitor the progress of digestions, determining how the gut mixes, propels, and stores contents.
