What are three things that the lining of the digestive tract defends surrounding tissues against?

The lining of the digestive tract defends surrounding tissues against pathogens, such as bacteria and viruses, that could cause infections. It also protects against harmful substances, including toxins and undigested food particles, which could lead to inflammation or damage. Additionally, the lining helps prevent the entry of allergens that could trigger immune responses and contribute to conditions like food Allergies.