What substance protects the stomach lining from damage due to digestive juices?

The thing that may protect the stomach from acids are:

1-The parietal and chief cells, which are located in the lining of the stomach, are impermeable to acids. Therefore they help to protect the stomach from acids.

2-The layer of alkaline (basic) mucus containing bicarbonate.

3-The tight junction between epithelial cells. It stops acids from leaking into the submucosa layer.

4-The rapid rate of cell division. This will allow damaged cells to be replaced.

5-The protection effects provided by prostaglandins that are produced by gastric mucosa.