Various defence mechanisms are found in the oesophagus which can be elicited by reflux damage. Premucosal defence includes bicarbonate ions and epidermal growth factor (EGF) secreted by salivary and oesophageal glands. The mucosa can respond by increasing epithelial cell turnover and upregulating EGF receptor and endocytosis. The intercellular barrier can be increased by the contents of membrane-coating granules. Local pH can be regulated by carbonic anhydrase. The whole viscus can exhibit peristalsis to effect a mechanical clearance of the refluxed gastric and duodenal material.