There are three main types of esophageal peristalsis: primary, secondary, and tertiary. Each plays a different role in moving food and liquid down the esophagus to the stomach.
Primary Peristalsis
Primary peristalsis is triggered by the act of swallowing. When you swallow, a wave of muscle contraction starts at the top of the esophagus and moves downwards, pushing the bolus of food or liquid ahead of it. This is a coordinated and powerful contraction designed to completely clear the esophagus after each swallow. Primary peristalsis typically lasts about 8-10 seconds.
Secondary Peristalsis
Secondary peristalsis is not triggered by swallowing. Instead, it is initiated by distension of the esophagus. If some food or liquid remains in the esophagus after a primary peristaltic wave, or if gastric contents reflux into the esophagus, stretch receptors in the esophageal wall are stimulated. This triggers a secondary peristaltic wave, which is a localized contraction designed to clear the remaining material from the esophagus. Secondary peristalsis can occur repeatedly until the esophagus is clear.
Tertiary Peristalsis
Tertiary peristalsis refers to uncoordinated, non-propulsive contractions that can occur in the esophagus. These contractions do not effectively move food or liquid towards the stomach and can even impede its passage. Tertiary peristalsis is more common in older individuals and can be associated with esophageal disorders such as diffuse esophageal spasm (DES). These contractions are often irregular, simultaneous, and of low amplitude. They are generally considered dysfunctional and do not contribute to normal esophageal emptying.
In summary, the esophagus utilizes primary peristalsis following swallowing, secondary peristalsis to clear residual material, and may exhibit tertiary peristalsis, which is a disordered motility pattern.
