Biological Systems MCAT Practice Exam

Which of the following is a component of the enteric nervous system?

1. Sympathetic plexus

2. Myenteric plexus

3. Cranial plexus

4. Coccygeal plexus

The correct answer is: Myenteric plexus

The myenteric plexus is a crucial component of the enteric nervous system, which is often referred to as the "second brain" of the gastrointestinal tract. This plexus lies between the longitudinal and circular muscle layers of the gastrointestinal wall and is primarily responsible for regulating gastrointestinal motility. It controls the smooth muscle contractions necessary for peristalsis, the coordinated movement that propels food through the digestive system. In addition to its role in motor function, the myenteric plexus also communicates with other parts of the enteric nervous system and integrates signals from the autonomic nervous system, allowing it to modulate digestive processes effectively. This system operates independently but also interacts with the central nervous system to coordinate overall digestive function. The other choices listed do not qualify as components of the enteric nervous system. The sympathetic plexus refers to the sympathetic part of the autonomic nervous system, which influences gastrointestinal function primarily through inhibition. The cranial plexus is involved in innervating the head and neck regions but is not specific to the gastrointestinal tract. The coccygeal plexus pertains to the lower back and is related to sensory and motor function in that region, not gastrointestinal control. Thus, the myenteric plexus is the correct