Final answer:
Disorders of the gastrointestinal (GI) tract are often caused by abnormal peristalsis, which are wave-like muscle contractions controlled by the myenteric plexus and modulated by hormones like motilin.
Step-by-step explanation:
Abnormally rapid or slow motility is often the cause of disorders of the gastrointestinal (GI) tract. Peristalsis, which is rapid, involuntary, wave-like contractions of smooth muscles, plays a critical role in pushing food through the GI tract. When peristalsis is disrupted, either because it is too rapid or too slow, it can result in various disorders. The myenteric plexus, part of the enteric nervous system, regulates the motility in the alimentary canal, and the hormone motilin initiates migrating motility complexes, which are a form of peristalsis in the small intestine that moves chyme through the digestive system.