Final answer:
The enteric nervous system (ENS) is responsible for controlling the digestive processes, functioning independently of the central nervous system and is part of the peripheral nervous system. It directly regulates the digestive tract's motility and secretion through neural tissue and myenteric plexuses.
Step-by-step explanation:
The enteric nervous system (ENS) is a complex network of neurons that plays a crucial role in controlling the digestive system. This particular division of the nervous system operates largely independently of the central nervous system (CNS) and is considered a part of the peripheral nervous system (PNS). The ENS consists of neural tissue associated with the digestive organs, including various myenteric plexuses which enable the direct regulation of digestive functions such as motility and secretion without the need for CNS intervention. It can be associated with the autonomic nervous system due to its autonomic functions that regulate digestion through neural connections. Ultimately, the ENS is critical for the autonomous regulation of digestive processes.
When discussing which part of the nervous system directly controls the digestive system, the correct answer is the enteric nervous system. Its functionality is evidenced when stretch receptors in the stomach respond to the filling and stretching of the stomach by directly activating the smooth muscle fibers to increase motility and accommodate the food intake. The ENS is specially adapted for this task as it doesn't require CNS oversight for such reflex actions. Hence, in the student's question, the enteric nervous system functions in controlling digestion (option 5).