Certified Neuroscience Registered Nurse (CNRN) Practice Exam

What effect does sympathetic stimulation have on the gastrointestinal system?

1. Increases motility and secretion

2. Promotes relaxation of sphincters

3. Inhibits the GI tract and decreases motility

4. Stimulates the production of digestive enzymes

The correct answer is: Inhibits the GI tract and decreases motility

Sympathetic stimulation plays a crucial role in the body’s response to stress and is associated with the "fight or flight" response. When the sympathetic nervous system is activated, it prioritizes functions that are essential for immediate survival rather than those related to digestion. Consequently, sympathetic stimulation inhibits the activities of the gastrointestinal (GI) tract. This includes a decrease in the motility of the intestines, which slows down the movement of food through the digestive system. This is an adaptive response, as redirecting blood flow away from the GI tract and reducing digestive activity allows the body to allocate its resources to more critical functions, such as increasing heart rate and redirecting blood to skeletal muscles. In contrast, increased motility and secretion would be more aligned with parasympathetic stimulation, which promotes digestion and nutrient absorption. Relaxation of sphincters is also characteristic of parasympathetic activity, allowing for easier passage through the digestive system. Similarly, stimulation of digestive enzyme production is part of this system's role in enhancing digestion. Thus, understanding the effects of sympathetic nervous system activation clarifies why the correct answer is the one highlighting inhibition of the GI tract and a decrease in motility.