How the Stomach Prevents Acid Reflux and Regulates Digestion

The stomach contains contents via four mechanisms:

1. Cardiac sphincter: Valve at esophagus-stomach junction prevents backflow.
2. Gastric peristalsis: Rhythmic contractions mix food with gastric juices and move it toward small intestine.
3. Rugae: Inner folds increase surface area for enzyme contact; collapse when empty to reduce volume.
4. Pyloric sphincter: Controls release of partially digested, acidic chyme into small intestine.

These ensure controlled processing before release.