Vagovagal reflex

Reflex action involving the vagus nerve

The vagovagal reflex is a reflex circuit within the autonomic nervous system that involves both afferent and efferent fibers of the vagus nerve. This reflex plays a crucial role in the regulation of gastrointestinal function, particularly in the control of stomach motility and secretion.

Mechanism

The vagovagal reflex is initiated by the distension of the stomach wall, which activates stretch receptors. These receptors send signals via afferent fibers of the vagus nerve to the medulla oblongata in the brainstem. The medulla processes these signals and sends efferent signals back through the vagus nerve to the stomach. This results in the relaxation of the stomach muscles, allowing it to accommodate more food, and stimulates the secretion of gastric acid and digestive enzymes.

Role in Digestion

The vagovagal reflex is essential for the proper functioning of the digestive system. It helps coordinate the peristaltic movements of the stomach and intestines, ensuring that food is mixed and propelled efficiently through the digestive tract. Additionally, it regulates the secretion of gastric juices necessary for the breakdown of food.

Clinical Significance

Dysfunction of the vagovagal reflex can lead to various gastrointestinal disorders. For instance, impaired reflex activity may contribute to conditions such as gastroparesis, where the stomach cannot empty properly, leading to symptoms like nausea and bloating. Conversely, excessive reflex activity might be involved in gastroesophageal reflux disease (GERD), where stomach contents flow back into the esophagus.

Related pages

• Vagus nerve
• Autonomic nervous system
• Gastrointestinal tract
• Peristalsis

References

• Berthoud, H. R., & Neuhuber, W. L. (2000). Functional and chemical anatomy of the afferent vagal system. Autonomic Neuroscience, 85(1-3), 1-17.
• Grundy, D. (2006). Neuroanatomy of visceral nociception: vagal and splanchnic afferent. Gut, 55(Suppl 2), ii10-ii13.

Diagram illustrating the control of stomach acid secretion, which is influenced by the vagovagal reflex.