Motilin

Definition

Motilin is a peptide hormone produced in the small intestine that plays a crucial role in regulating gastrointestinal motility, particularly during fasting. It is primarily responsible for initiating the migrating motor complex (MMC), which helps to clear undigested food and debris from the digestive tract between meals. This hormone contributes to the coordination of contractions in the gastrointestinal smooth muscle, ensuring proper digestive function.

5 Must Know Facts For Your Next Test

1. Motilin is secreted primarily by the M cells of the small intestine, particularly in response to fasting or during specific phases of digestion.
2. The release of motilin occurs in cycles, typically every 90 minutes, coinciding with the phases of the migrating motor complex.
3. Motilin not only stimulates gastric motility but also promotes coordination among the muscles of the gastrointestinal tract, enhancing overall digestive efficiency.
4. Increased levels of motilin can lead to enhanced gastrointestinal motility, while decreased levels may result in slower transit times and potential digestive issues.
5. Motilin receptors are found throughout the gastrointestinal tract, indicating its widespread influence on digestive processes and gut health.

Review Questions

• How does motilin contribute to the regulation of gastrointestinal motility during fasting periods?
  • Motilin plays a vital role in regulating gastrointestinal motility by initiating the migrating motor complex (MMC), which occurs every 90 minutes during fasting. This peptide hormone stimulates rhythmic contractions of the smooth muscles in the gastrointestinal tract, helping to clear undigested food and debris. The coordinated activity promoted by motilin ensures that the digestive system remains efficient and prepares for the next meal.
• Discuss the relationship between motilin and other gastrointestinal hormones like gastrin and cholecystokinin.
  • Motilin works in conjunction with other gastrointestinal hormones such as gastrin and cholecystokinin to regulate digestion. While gastrin stimulates gastric acid secretion and promotes gastric motility, cholecystokinin is responsible for gallbladder contraction and enzyme release from the pancreas. Together, these hormones create a complex hormonal interplay that optimizes digestive function, with motilin specifically enhancing motility during fasting and facilitating transition into feeding phases.
• Evaluate how abnormalities in motilin secretion could impact overall gastrointestinal health and function.
  • Abnormalities in motilin secretion can lead to significant impacts on gastrointestinal health, resulting in issues like delayed gastric emptying or increased transit times. If motilin levels are too low, it may hinder proper clearance of undigested food, leading to symptoms like bloating and discomfort. Conversely, excessively high levels of motilin could cause rapid transit, potentially resulting in diarrhea. Understanding these dynamics is essential for managing gastrointestinal disorders effectively.

Related terms

migrating motor complex: A pattern of electromechanical activity that occurs in the gastrointestinal tract during fasting, helping to clear residual food and prevent bacterial overgrowth.

gastrin: A hormone produced in the stomach that stimulates gastric acid secretion and promotes gastric motility, working alongside motilin in the regulation of digestion.

cholecystokinin: A hormone released by the small intestine that stimulates gallbladder contraction and enzyme secretion from the pancreas, playing a key role in digestion after food intake.