Conversation so far:
where is the enteric nervous system found
The enteric nervous system is embedded in the lining of the gastrointestinal system, beginning in the esophagus and extending down to the anus.
what is the purpose of the enteric nervous system
The enteric nervous system governs the function of the gastrointestinal tract.
what is a nickname of the enteric nervous system
The ENS is also called the second brain.
why is the enteric nervous system nicknamed the second brain
The enteric nervous system is called the second brain mainly because it can operate autonomously.

Question: how many neurons make up the system
Self-contained rewrite: how many neurons make up the enteric nervous system