- The enteric nervous system (ENS) is a complex network of neurons that governs the function of the gastrointestinal tract.
- It is often referred to as the "second brain" because it can operate independently of the central nervous system.
- However, its activity is modulated by both divisions of the autonomic nervous system for fine-tuned regulation.

- The parasympathetic nervous system primarily stimulates gastrointestinal activity, promoting digestion by increasing motility, secretion, and blood flow to the gut.
- In contrast, the sympathetic nervous system generally inhibits gastrointestinal functions, reducing motility and secretion while constricting blood vessels to the digestive organs.

- It is important to note that the somatic nervous system controls voluntary muscle movements and does not regulate the enteric nervous system.
- Therefore, the best description of the regulation of the ENS is that it is under the control of both the sympathetic and parasympathetic divisions of the autonomic nervous system.

Reference: Guyton and Hall Textbook of Medical Physiology, 13th Edition, Chapter 65: The Enteric Nervous System and Gastrointestinal Hormones